Transfer hydrogenation of cyclopamine analogs

Abstract

Provided herein is a process for the transfer-hydrogenation of ketone analogs of members of the jervine type of Veratrum alkaloids, such as cyclopamine. Also provided herein are novel ruthenium transfer-hydrogenation catalysts.

Description

BACKGROUND

Cyclopamine, a natural product isolated from Veratrum californicum, has emerged as a significant pharmacological tool to validate the Hedgehog (Hh) pathway in cancer. Cyclopamine directly acts on SMO and inhibits tumor growth in several murine models of pancreatic, medulloblastoma, prostate, small cell lung, and digestive tract cancers. However, the clinical development of cyclopamine as a therapeutic in cancer is hampered by its poor solubility, acid sensitivity, and weak potency relative to other reported small-molecule Hh antagonists.

There has been considerable focus on the development of novel cyclopamine analogues with improved potency, and improved pharmacokinetic and pharmaceutical properties relative to cyclopamine (see, for example, U.S. Pat. Nos. 7,230,004 and 7,407,967, incorporated herein by reference in its entirety). From that effort, a seven-membered D-ring sulfonamide analogue of cyclopamine, IPI-926, emerged as a clinical development candidate (see, Tremblay et al., “Discovery of a Potent and Orally Active Hedgehog Pathway Antagonist (IPI-926)” J. Med. Chem. (2009) 52:4400-4418, incorporated herein by reference in its entirety). Large quantities of IPI-926 are required for clinical development. Moreover, other promising amino analogues can be synthesized following routes similar to that used to generate IPI-926.

In an exemplary approach to the synthesis of IPI-926, an intermediate ketone (I-a) requires reduction to its corresponding alcohol (II-a) such that the IPI-926 sulfonamide substituent can be installed (see, FIG. 1). Known methods for ketone reduction on cyclopamine analogs such as (I-a) include, but are not limited to, the use of K-selectride as the reducing agent (see, e.g., Tremblay ibid.; U.S. Pat. No. 7,812,164, incorporated herein by reference in its entirety). However, this reaction is exothermic and requires cryogenic temperatures (e.g., below −20° C.). Moreover, the exothermic oxidative work-up with hydrogen peroxide poses significant challenges for pilot plant production. Thus, a milder reduction procedure with a more facile work-up for large scale reactions is desirable.

SUMMARY

Provided herein is a process for the transfer-hydrogenation of cyclopamine analogues. Also provided herein are novel ruthenium transfer-hydrogenation catalysts.

For example, in one aspect, provided herein is a process for preparing a compound of formula (II):

or its pharmaceutically acceptable forms thereof;

from a compound of formula (I):

or its pharmaceutically acceptable forms thereof;

wherein:

R¹ is H, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl, heteroaralkyl, haloalkyl, —OR¹⁶, —C(O)R¹⁶, —CO₂R¹⁶, —SO₂R¹⁶, —C(O)N(R¹⁷)(R¹⁷), —[C(R¹⁶)₂]_q—R⁶, —[(W)—N(R¹⁷)C(O)]_qR¹⁶, —[(W)—C(O)]_qR¹⁶, —[(W)—C(O)O]_qR¹⁶, —[(W)—OC(O)]_qR¹⁶, —[(W)—SO₂]_qR¹⁶, —[(W)—N(R¹⁷)SO₂]_qR¹⁶, —[(W)—C(O)N(R¹⁷)]_qR¹⁷, —[(W)—O]_qR¹⁶, —[(W)—N(R¹⁷)]_qR¹⁶, or —[(W)—S]_qR¹⁶; wherein W is a diradical and q is 1, 2, 3, 4, 5, or 6;

each R² and R³ is, independently, H, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl, heteroaralkyl, haloalkyl, halo, —OR¹⁶, —OR¹⁶, —N(R¹⁷)₂, or —SR¹⁶, or R² and R³ taken together form a double bond or form a group:

wherein Z is NR¹⁷, O, or C(R¹⁸)₂;

R⁴ is independently H, halo, —OR¹⁶, —N(R¹⁷)₂, or —SR¹⁶;

each R⁵ and R⁶, is, independently, H, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl, heteroaralkyl, halo, —OR¹⁶, —N(R¹⁷)₂, or —SR¹⁶; or R⁵ and R⁶ taken together with the carbon to which they are bonded form C═O, C═S, C═N—OR¹⁷, C═N—R¹⁷, C═N—N(R¹⁷)₂, or form an optionally substituted 3-8 membered ring;

each R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹² and R¹³ is, independently, H, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl, heteroaralkyl, halo, —OR¹⁶, —N(R¹⁷)₂, or —SR¹⁶;

or R¹¹ and R¹² taken together, form a double bond;

or R¹⁰ and R¹¹ taken together, or R¹¹ and R¹² taken together, form a group:

wherein Z is NR¹⁷, O, or C(R¹⁸)₂;

each R¹⁴ and R¹⁵ is, independently, H, halo, —OR¹⁶, —N(R¹⁷)₂, or —SR¹⁶; or R¹⁴ and R¹⁵ taken together with the carbon to which they are bonded form C═O or C═S;

X is a bond or the group —C(R¹⁹)₂—, wherein each R¹⁹ is, independently, H, alkyl, aralkyl, halo, —CN, —OR¹⁶, or —N(R¹⁷)₂;

R¹⁶ is H, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl, heteroaralkyl or —[C(R²⁰)₂]_p—R²¹ wherein p is 0-6; or any two occurrences of R¹⁶ on the same substituent are taken together to form a 4-8 membered optionally substituted ring;

R¹⁷ is H, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl, heteroaralkyl, —C(═O)R²⁰, —C(═O)OR²⁰, —SO₂R²⁰, —C(═O)N(R²⁰)₂, or —[C(R²⁰)₂]_p—R²¹ wherein p is 0-6; or any two occurrences of R¹⁷ on the same substituent are taken together to form a 4-8 membered optionally substituted ring;

R¹⁸ is H, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl, heteroaralkyl, halo, —CN, —OR²⁰, —OSi(R²⁰)₃, —C(═O)R²⁰, —C(═O)OR²⁰, —SO₂R²⁰ or —C(═O)N(R²⁰)₂;

R²⁰ is H, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl, or heteroaralkyl; or any two occurrences of R²⁰ on the same substituent are taken together to form a 4-8 membered optionally substituted ring;

R²¹ is —OR²², —N(R²²)C(═O)R²², —N(R²²)C(═O)OR²², —N(R²²)SO₂(R²²), —C(═O)R²²N(R²²)₂, —OC(═O)R²²N(R²²)(R²²), —SO₂N(R²²)(R²²), —N(R²²)(R²²), —C(═O)OR²², —C(═O)N(OH)(R²²), —OS(O)₂OR²², —S(O)₂OR²², —OP(═O)(OR²²)(OR²²), —N(R²²)P(O)(OR²²)(OR²²), or —P(═O)(OR²²)(OR²²); and

R²² is H, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl, heteroaralkyl; or any two occurrences of R²² on the same substituent are taken together to form a 4-8 membered optionally substituted ring;

the process comprising reacting a compound of formula (I) or its pharmaceutically acceptable forms thereof with a transfer-hydrogenation catalyst in order to provide a compound of formula (II) or its pharmaceutically acceptable forms thereof.

In certain embodiments, the process preferentially generates a compound of formula (II), or its pharmaceutically acceptable forms thereof, wherein the newly-formed hydroxyl group has the β (beta) orientation, meaning that the newly-formed hydroxyl group is above the plane of the ring in formula (II). In these embodiments, the bond between the newly-formed hydroxyl group and the ring carbon atom to which the newly formed hydroxyl group is attached is shown as a solid line (e.g., , , and the like).

In other embodiments, the process generates a compound of formula (II), or its pharmaceutically acceptable forms thereof, wherein the newly-formed hydroxyl group has the α (alpha) orientation, meaning that the newly-formed hydroxyl group is below the plane of the ring in formula (II). In these embodiments, the bond between the newly-formed hydroxyl group and the ring carbon atom to which the newly formed hydroxyl group is attached is shown as a dashed line (e.g., ∥∥∥∥, -----, and the like).

In certain embodiments, the process preferentially generates a compound of formula (II), or its pharmaceutically acceptable forms thereof, wherein the carbon atom that is directly attached to the newly-formed hydroxyl group has the (S) configuration.

In other embodiments, the process generates a compound of formula (II), or its pharmaceutically acceptable forms thereof, wherein the carbon atom that is directly attached to the newly-formed hydroxyl group has the (R) configuration.

In certain embodiments, the process preferentially generates a compound of formula (II), or its pharmaceutically acceptable forms thereof, wherein the newly-formed hydroxyl group has the β (beta) orientation, and the carbon atom that is directly attached to the newly-formed hydroxyl group has the (S) configuration.

In certain embodiments, the process generates a compound of formula (II), or its pharmaceutically acceptable forms thereof, wherein the newly-formed hydroxyl group has the β (beta) orientation, and the carbon atom that is directly attached to the newly-formed hydroxyl group has the (R) configuration.

In other embodiments, the process generates a compound of formula (II), or its pharmaceutically acceptable forms thereof, wherein the newly-formed hydroxyl group has the α (alpha) orientation, and the carbon atom that is directly attached to the newly-formed hydroxyl group has the (R) configuration.

In other embodiments, the process generates a compound of formula (II), or its pharmaceutically acceptable forms thereof, wherein the newly-formed hydroxyl group has the α (alpha) orientation, and the carbon atom that is directly attached to the newly-formed hydroxyl group has the (S) configuration.

For example, in one aspect, provided herein is a process for preparing a compound of formula (II):

or its pharmaceutically acceptable forms thereof;from a compound of formula (I):

or its pharmaceutically acceptable forms thereof;wherein:

R¹ is alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl, heteroaralkyl, haloalkyl, heteroalkyl, —C(O)R¹⁶, —CO₂R¹⁶, —SO₂R¹⁶, —C(O)N(R¹⁷)(R⁷), —[C(R²³)₂]_q—R²³, —[(W)—N(R¹⁷)C(O)]_qR¹⁶, —[(W)—C(O)N(R¹⁷)]_qR¹⁷, —[(W)—N(R¹⁷)]_qR¹⁶, or —[(W)—S]_qR¹⁶; wherein W is (CH₂)_q and each q is independently 1, 2, 3, 4, 5, or 6;

each R² and R³ is, independently, H, alkyl, alkenyl, alkynyl, aralkyl, heteroaralkyl, haloalkyl, heteroalkyl, CN, NO₂, halo, —OR¹⁶, —N(R¹⁷)₂, or —SR¹⁶, or R² and R³ taken together form a double bond or form a group:

wherein Z is NR¹⁷, O, or C(R¹⁸)₂;

R⁴ is H, halo, —OR¹⁶, —N(R¹⁷)₂, or —SR¹⁶;

each R⁵ and R⁶, is, independently, H, alkyl, alkenyl, alkynyl, aralkyl, heteroaralkyl, heteroalkyl; or R⁵ and R⁶ taken together with the carbon to which they are bonded form C═O or C═S;

each R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹² and R¹³ is, independently, H, alkyl, alkenyl, alkynyl, aralkyl, heteroaralkyl, heteroalkyl, halo, or —OR¹⁶, or R¹¹ and R¹² taken together, form a double bond;

each R¹⁴ and R¹⁵ is, independently, H, alkyl, alkenyl, alkynyl, aralkyl, heteroaralkyl, heteroalkyl, halo, —OR¹⁶, —N(R¹⁷)₂, or —SR¹⁶; or R¹⁴ and R¹⁵ taken together with the carbon to which they are bonded form C═O or C═S;

X is a bond or the group —C(R¹⁹)₂—, wherein each R¹⁹ is, independently, H, alkyl, alkenyl, alkynyl, aralkyl, heteroaralkyl, heteroalkyl, halo, —CN, —NO₂, —OR¹⁶, or —N(R¹⁷)₂;

R¹⁶ is alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl, or heteroaralkyl; or any two occurrences of R¹⁶ on the same substituent are taken together to form a 4-8 membered optionally substituted ring;

R¹⁷ is H, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl, heteroaralkyl, —C(═O)R²⁰, —C(═O)OR²⁰, —SO₂R²⁰, or —C(═O)N(R²⁰)₂; or any two occurrences of R¹⁷ on the same substituent are taken together to form a 4-8 membered optionally substituted ring;

R¹⁸ is H, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl, heteroaralkyl, heteroalkyl, halo, —CN, —OR²⁰, —OSi(R²⁰)₃, —N(R¹⁷)₂, —C(═O)R²⁰, —C(═O)OR²⁰, —SO₂R²⁰ or —C(═O)N(R²⁰)₂;

R²⁰ is H, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl, or heteroaralkyl; or any two occurrences of R²⁰ on the same substituent are taken together to form a 4-8 membered optionally substituted ring; and

R²³ is H, alkyl, alkenyl, alkynyl, amido, or amino;

the process comprising reacting a compound of formula (I) or its pharmaceutically acceptable forms thereof with a transfer-hydrogenation catalyst in order to provide a compound of formula (II) or its pharmaceutically acceptable forms thereof.

For example, in one aspect, provided herein is a process for preparing a compound of formula (II):

or its pharmaceutically acceptable forms thereof;

from a compound of formula (I):

or its pharmaceutically acceptable forms thereof;

wherein:

R¹ is alkyl, alkenyl, alkynyl, aralkyl, —C(O)R¹⁶, —CO₂R¹⁶, —SO₂R¹⁶, —[C(R²³)₂]_q—R²³, —[(W)—N(R¹⁷)C(O)]_qR¹⁶, —[(W)—C(O)N(R¹⁷)]_qR¹⁷ or —[(W)—N(R¹⁷)]_qR¹⁶, W is (CH₂)_q and each q is independently 1, 2, 3, 4, 5, or 6;

R⁵ and R⁶ are each H, or R⁵ and R⁶ taken together with the carbon to which they are bonded form C═O;

R¹¹ and R¹² are each H (e.g., R¹¹ is hydrogen in the α or β-position), or R¹¹ and R¹² taken together form a double bond;

X is a bond or the group —CH₂—;

R¹⁶ is alkyl, alkenyl, alkynyl, aralkyl, alkoxy, arylalkoxy, or heteroaralkyl;

R¹⁷ is H, alkyl, alkenyl, or alkynyl; and

R²³ is H, alkyl, alkenyl, alkynyl, amido, or amino;

the process comprising reacting a compound of formula (I) or its pharmaceutically acceptable forms thereof with a transfer-hydrogenation catalyst in order to provide a compound of formula (II) or its pharmaceutically acceptable forms thereof.

In certain embodiments, the compound of formula (I) is a compound of formula (I-a):

or its pharmaceutically acceptable forms thereof,

and the compound of formula (II) is a compound of formula (S)-(II-a):

or its pharmaceutically acceptable forms thereof.

In certain embodiments, the transfer-hydrogenation catalyst is a ruthenium transfer-hydrogenation catalyst.

In certain embodiments, the ruthenium transfer-hydrogenation catalyst comprises an amino alcohol ligand.

In certain embodiments, the amino alcohol ligand is of the formula (i-a):

or its pharmaceutically acceptable forms thereof,

wherein each R^a and R^b are independently selected from hydrogen, alkyl, perhaloalkyl, alkenyl, alkynyl, carbocycle, heterocycle, aryl, heteroaryl, aralkyl, or heteroaralkyl, or R^a and R^b are joined to form a 3-8 membered carbocyclic or heterocyclic ring system;

and R^c is selected from alkyl, perhaloalkyl, alkenyl, alkynyl, carbocycle, heterocycle, aryl, heteroaryl, aralkyl, or heteroaralkyl.

In certain embodiments, each R^a and R^b are independently selected from C_1-6 alkyl and C_1-6 perhaloalkyl. In certain embodiments, each R^a and R^b are independently selected from C_1-6 alkyl. In certain embodiments, each R^a and R^b are methyl.

In certain embodiments, R^c is C_1-6 alkyl. In certain embodiments, R^c is C_1-3 alkyl. In certain embodiments, R^c is —CH₂CH₃.

In certain embodiments, the ruthenium transfer-hydrogenation catalyst is an achiral ruthenium transfer-hydrogenation catalyst.

In certain embodiments, the ruthenium transfer-hydrogenation catalyst is an achiral ruthenium transfer-hydrogenation catalyst comprising an amino alcohol ligand of the formula (i-a) where R^a and R^b are the same group. For example, in certain embodiments, R^a and R^b are the same group selected from C_1-6 alkyl and C_1-6 perhaloalkyl. In certain embodiments, R^a and R^b are the same group selected from C_1-6 alkyl. In certain embodiments, R^a and R^b are both —CH₃.

In certain embodiments, the ruthenium transfer-hydrogenation catalyst is a chiral ruthenium transfer-hydrogenation catalyst.

In certain embodiments, the ruthenium transfer-hydrogenation catalyst is a chiral ruthenium transfer-hydrogenation catalyst comprising an amino alcohol ligand of the formula (i-a). For example, in certain embodiments, R^a is hydrogen and R^b is C_1-6 alkyl, or R^b is hydrogen and R^a is C_1-6 alkyl. In certain embodiments, R^a is hydrogen and R^b is C_1-6 alkyl, or R^b is hydrogen and R^a is C_1-6 alkyl.

In certain embodiments, the amino alcohol ligand is of the formula (i-b):

In certain embodiments, the amino alcohol ligand is of the formula (i-c):

In certain embodiments, the amino alcohol ligand is of the formula (i-i):

In certain embodiments, the amino alcohol ligand is of the formula (i-j):

In some embodiments, the amino alcohol ligand is of Formula (i-z):

or its pharmaceutically acceptable forms thereof,

wherein each R^a and R^b are independently selected from hydrogen, alkyl, perhaloalkyl, alkenyl, alkynyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, aralkyl, and heteroaralkyl, or R^a and R^b are joined to form a 3-10 membered carbocyclic or heterocyclic ring system;

each Rⁿ and R^o are independently selected from hydrogen, alkyl, perhaloalkyl, alkenyl, alkynyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, aralkyl, and heteroaralkyl, or Rⁿ and R^o are joined to form a 3-10 membered carbocyclic or heterocyclic ring system; or

R^a and Rⁿ are joined together to form a 3-10 membered carbocyclic or heterocyclic ring system and R^b and R^o are each hydrogen; or

R^a and R^o are joined together to form a 3-10 membered carbocyclic or heterocyclic ring system and R^b and Rⁿ are each hydrogen; or

R^b and R^o are joined together to form a 3-10 membered carbocyclic or heterocyclic ring system and R^a and Rⁿ are each hydrogen; or

R^b and Rⁿ are joined together to form a 3-10 membered carbocyclic or heterocyclic ring system and R^a and R^o are each hydrogen; and

R^c is selected from alkyl, perhaloalkyl, alkenyl, alkynyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, aralkyl, and heteroaralkyl; or

R^a and R^c are joined together to form a 3-10 membered carbocyclic or heterocyclic ring system and R^b is hydrogen; or

R^b and R^c are joined together to form a 3-10 membered carbocyclic or heterocyclic ringsystem and R^a is hydrogen.

In certain embodiments, the ruthenium transfer-hydrogenation catalyst is a chiral ruthenium transfer-hydrogenation catalyst comprising an amino alcohol ligand of the formula (i-z). For example, in certain embodiments, R^a is hydrogen and R^b is C_1-6 alkyl, or R^b is hydrogen and R^a is C_1-6 alkyl. In certain embodiments, R^a is hydrogen and R^b is Me, or R^b is hydrogen and R^a is Me. In certain embodiments, Rⁿ is aryl and R^o is hydrogen, or R^o is hydrogen and Rⁿ is aryl. In certain embodiments, Rⁿ is phenyl and R^o is hydrogen, or R^o is hydrogen and Rⁿ is phenyl.

In certain embodiments, the ruthenium transfer-hydrogenation catalyst further comprises an optionally substituted benzene ligand. In certain embodiments, the optionally substituted benzene ligand is hexamethylbenzene.

In certain embodiments, the ruthenium transfer-hydrogenation catalyst further comprises a halo ligand. In certain embodiments, the halo ligand is chloro.

In certain embodiments, the ruthenium transfer-hydrogenation catalyst is generated from hexamethylbenzene ruthenium chloride dimer and an amino alcohol.

In certain embodiments, the ruthenium transfer-hydrogenation catalyst is an achiral catalyst of the formula (iii-a):

wherein:

each R^a and R^b are the same group selected from hydrogen, alkyl, perhaloalkyl, alkenyl, alkynyl, carbocycle, heterocycle, aryl, heteroaryl, aralkyl, or heteroaralkyl, or R^a and R^b are joined to form a 3-8 membered carbocyclic or heterocyclic ring system;

R^c is selected from alkyl, perhaloalkyl, alkenyl, alkynyl, carbocycle, heterocycle, aryl, heteroaryl, aralkyl, or heteroaralkyl; and

each R^h, Rⁱ, R^j, R^k, R^l, and R^m are independently selected from hydrogen, alkyl, perhaloalkyl, alkenyl, alkynyl, carbocycle, heterocycle, aryl, heteroaryl, aralkyl, or heteroaralkyl.

In certain embodiments, the ruthenium transfer-hydrogenation catalyst is of the formula (iii-b):

In certain embodiments, the ruthenium transfer-hydrogenation catalyst is of the formula (iii-c):

In certain embodiments, the ruthenium transfer-hydrogenation catalyst is of the formula (iii-d):

In certain embodiments, the ruthenium transfer-hydrogenation catalyst is of the formula (iii-g):

In certain embodiments, the ruthenium transfer-hydrogenation catalyst is of the formula (iii-h):

In certain embodiments, the ruthenium transfer-hydrogenation catalyst is a chiral ruthenium transfer-hydrogenation catalyst selected from Cl3[((R)-tol-BINAP)RuCl]2-Me2NH2+, Cl3 [((S)-tol-BINAP)RuCl]2-Me2NH2+, ((R)-DIFLUORPHOS)RuCl2(DMF)n, ((S)-DIFLUORPHOS)RuCl2(DMF)n, ((R)-DTBM-SEGPHOS)RuCl2(p-cymene), ((S)-DTBM-SEGPHOS)RuCl2(p-cymene), Cl3 [((R)-xylyl-SEGPHOS)RuCl]2-Me2NH2+, Cl3[((S)-xylyl-SEGPHOS)RuCl]2-Me2NH2+, ((R)-xylyl-SEGPHOS)RuCl2(R,R)DPEN, ((S)-xylyl-SEGPHOS)RuCl2(S,S)DPEN, (Ph3P)RuCl2((+)-(R)—Fe-oxazoline), (Ph3P)RuCl2((−)-(S)—Fe-oxazoline), ((S,R)JOSIPHOS)RuCl2(DMF)n, ((R,S)JOSIPHOS)RuCl2(DMF)n, (11bS,11′bS)-4,4′-(9,9-Dimethyl-9H-xanthene-4,5-diyl)bis-dinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepine and its enantiomer, (S,S)TsDPEN-RuCl(p-cymene), (S,S)TsDPEN-RuCl(hexamethylbenzene), (S,S)TsCyDN-RuCl(hexamethylbenzene), RuHCl(mesitylene) [(1S,2R)-ephedrine], RuHCl(hexamethylbenzene)[(1S,2R)-ephedrine], RuHCl(hexamethylbenzene) [(1R,2S)-ephedrine], RuHCl(p-cymene)[(1S,2R)-ephedrine], RuHCl(p-cymene)[(1R,2S)-ephedrine], RuHCl(benzene)[(1S,2R)-ephedrine], RuHCl(mesitylene)[(1R,2S)₂-methylaminocyclohexanol], RuHCl(hexamethylbenzene)[(1R,2S)₂-methylaminocyclohexanol], RuHCl(hexamethylbenzene) [(1S,2S)₂-methylaminocyclohexanol], RuHCl(p-cymene) [(1R,2S)₂-methylaminocyclohexanol], and RuHCl(benzene)[(1R,2S)₂-methylaminocyclohexanol], RuHCl(hexamethylbenzene) [R-propranolol], RuHCl(hexamethylbenzene) [S-propranolol], RuHCl(hexamethylbenzene) [1R,2S-cis-1-amino-2-indanol], and RuHCl(hexamethylbenzene) [D-prolinol].

Also provided herein is a catalyst of the formula (iii-a):

wherein R^a and R^b are the same group selected from C_1-6 alkyl and C_1-6 perhaloalkyl, or R^a and R^b are joined to form a 3-8 membered carbocyclic or heterocyclic ring system;

R^c is selected from C_1-6 alkyl, C_1-6 perhaloalkyl, aralkyl, heteroaralkyl, aryl and heteroaryl; and

each R^h, Rⁱ, R^j, R^k, R^l, and R^m are independently selected from hydrogen, alkyl, perhaloalkyl, alkenyl, alkynyl, carbocycle, heterocycle, aryl, heteroaryl, aralkyl, or heteroaralkyl.

Also provided herein is a catalyst of the formula (iii-h):

wherein each R^a, R^b, Rⁿ and R^o are independently selected from hydrogen, alkyl, aryloxyalkyl, aryl, and perhaloalkyl, or

R^a and Rⁿ are joined together to form a 3-10 membered carbocyclic or heterocyclic ring system and R^b and R^o are each hydrogen; or

R^a and R^o are joined together to form a 3-10 membered carbocyclic or heterocyclic ring system and R^b and Rⁿ are each hydrogen; or

R^b and R^o are joined together to form a 3-10 membered carbocyclic or heterocyclic ring system and R^a and Rⁿ are each hydrogen; or

R^b and Rⁿ are joined together to form a 3-10 membered carbocyclic or heterocyclic ring system and R^a and R^o are each hydrogen; and

R^c is selected from C_1-6 alkyl, C_1-6 perhaloalkyl, aralkyl, heteroaralkyl, aryl and heteroaryl; and

each R^h, Rⁱ, R^j, R^k, R^l, and R^m are independently selected from hydrogen, alkyl, perhaloalkyl, alkenyl, alkynyl, carbocycle, heterocycle, aryl, heteroaryl, aralkyl, or heteroaralkyl.

The details of additional or alternative embodiments are set forth in the accompanying Detailed Description and Exemplification as described below. Other features, objects, and advantages of the invention will be apparent from this description and from the claims.

Definitions

While specific embodiments have been discussed, the specification is illustrative only and not restrictive. Many variations of this disclosure will become apparent to those skilled in the art upon review of this specification.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this specification pertains.

As used in the specification and claims, the singular form “a”, “an” and “the” includes plural references unless the context clearly dictates otherwise.

Definitions of specific functional groups and chemical terms are described in more detail below. For purposes of this invention, the chemical elements are identified in accordance with the Periodic Table of the Elements, CAS version, Handbook of Chemistry and Physics, 75^th Ed., inside cover, and specific functional groups are generally defined as described therein. Additionally, general principles of organic chemistry, as well as specific functional moieties and reactivity, are described in, for example, Organic Chemistry, Thomas Sorrell, University Science Books, Sausalito, 1999; Smith and March March's Advanced Organic Chemistry, 5^th Edition, John Wiley & Sons, Inc., New York, 2001; Larock, Comprehensive Organic Transformations, VCH Publishers, Inc., New York, 1989; and Carruthers, Some Modern Methods of Organic Synthesis, 3^rd Edition, Cambridge University Press, Cambridge, 1987.

As used herein, a “pharmaceutically acceptable form” of a disclosed compound includes, but is not limited to, pharmaceutically acceptable salts, hydrates, solvates, isomers, prodrugs, and isotopically labeled derivatives of disclosed compounds.

In certain embodiments, the pharmaceutically acceptable form is a pharmaceutically acceptable salt. As used herein, the term “pharmaceutically acceptable salt” refers to those salts which are, within the scope of sound medical judgment, suitable for use in contact with the tissues of subjects without undue toxicity, irritation, allergic response and the like, and are commensurate with a reasonable benefit/risk ratio. Pharmaceutically acceptable salts are well known in the art. For example, Berge et al. describes pharmaceutically acceptable salts in detail in J. Pharmaceutical Sciences (1977) 66:1-19. Pharmaceutically acceptable salts of the compounds provided herein include those derived from suitable inorganic and organic acids and bases. Examples of pharmaceutically acceptable, nontoxic acid addition salts are salts of an amino group formed with inorganic acids such as hydrochloric acid, hydrobromic acid, phosphoric acid, sulfuric acid and perchloric acid or with organic acids such as acetic acid, oxalic acid, maleic acid, tartaric acid, citric acid, succinic acid or malonic acid or by using other methods used in the art such as ion exchange. Other pharmaceutically acceptable salts include adipate, alginate, ascorbate, aspartate, benzenesulfonate, besylate, benzoate, bisulfate, borate, butyrate, camphorate, camphorsulfonate, citrate, cyclopentanepropionate, digluconate, dodecylsulfate, ethanesulfonate, formate, fumarate, glucoheptonate, glycerophosphate, gluconate, hemisulfate, heptanoate, hexanoate, hydroiodide, 2-hydroxy-ethanesulfonate, lactobionate, lactate, laurate, lauryl sulfate, malate, maleate, malonate, methanesulfonate, 2-naphthalenesulfonate, nicotinate, nitrate, oleate, oxalate, palmitate, pamoate, pectinate, persulfate, 3-phenylpropionate, phosphate, picrate, pivalate, propionate, stearate, succinate, sulfate, tartrate, thiocyanate, p-toluenesulfonate, undecanoate, valerate salts, and the like. In some embodiments, organic acids from which salts can be derived include, for example, acetic acid, propionic acid, glycolic acid, pyruvic acid, oxalic acid, maleic acid, malonic acid, succinic acid, fumaric acid, tartaric acid, citric acid, benzoic acid, cinnamic acid, mandelic acid, methanesulfonic acid, ethanesulfonic acid, p-toluenesulfonic acid, salicylic acid, and the like.

Pharmaceutically acceptable salts derived from appropriate bases include alkali metal, alkaline earth metal, ammonium and N⁺(C_1-4alkyl)⁴- salts. Representative alkali or alkaline earth metal salts include sodium, lithium, potassium, calcium, magnesium, iron, zinc, copper, manganese, aluminum, and the like. Further pharmaceutically acceptable salts include, when appropriate, nontoxic ammonium, quaternary ammonium, and amine cations formed using counterions such as halide, hydroxide, carboxylate, sulfate, phosphate, nitrate, lower alkyl sulfonate and aryl sulfonate. Organic bases from which salts can be derived include, for example, primary, secondary, and tertiary amines, substituted amines including naturally occurring substituted amines, cyclic amines, basic ion exchange resins, and the like, such as isopropylamine, trimethylamine, diethylamine, triethylamine, tripropylamine, and ethanolamine. In some embodiments, the pharmaceutically acceptable base addition salt is chosen from ammonium, potassium, sodium, calcium, and magnesium salts.

In certain embodiments, the pharmaceutically acceptable form is a “solvate” (e.g., a hydrate). As used herein, the term “solvate” refers to compounds that further include a stoichiometric or non-stoichiometric amount of solvent bound by non-covalent intermolecular forces. The solvate can be of a disclosed compound or a pharmaceutically acceptable salt thereof. Where the solvent is water, the solvate is a “hydrate”. Pharmaceutically acceptable solvates and hydrates are complexes that, for example, can include 1 to about 100, or 1 to about 10, or one to about 2, 3 or 4, solvent or water molecules. It will be understood that the term “compound” as used herein encompasses the compound and solvates of the compound, as well as mixtures thereof.

In certain embodiments, the pharmaceutically acceptable form is a prodrug. As used herein, the term “prodrug” refers to compounds that are transformed in vivo to yield a disclosed compound or a pharmaceutically acceptable form of the compound. A prodrug can be inactive when administered to a subject, but is converted in vivo to an active compound, for example, by hydrolysis (e.g., hydrolysis in blood). In certain cases, a prodrug has improved physical and/or delivery properties over the parent compound. Prodrugs are typically designed to enhance pharmaceutically and/or pharmacokinetically based properties associated with the parent compound. The prodrug compound often offers advantages of solubility, tissue compatibility or delayed release in a mammalian organism (see, e.g., Bundgard, H., Design of Prodrugs (1985), pp. 7-9, 21-24 (Elsevier, Amsterdam). A discussion of prodrugs is provided in Higuchi, T., et al., “Pro-drugs as Novel Delivery Systems,” A.C.S. Symposium Series, Vol. 14, and in Bioreversible Carriers in Drug Design, ed. Edward B. Roche, American Pharmaceutical Association and Pergamon Press, 1987, both of which are incorporated in full by reference herein. Exemplary advantages of a prodrug can include, but are not limited to, its physical properties, such as enhanced water solubility for parenteral administration at physiological pH compared to the parent compound, or it enhances absorption from the digestive tract, or it can enhance drug stability for long-term storage.

The term “prodrug” is also meant to include any covalently bonded carriers, which release the active compound in vivo when such prodrug is administered to a subject. Prodrugs of an active compound, as described herein, can be prepared by modifying functional groups present in the active compound in such a way that the modifications are cleaved, either in routine manipulation or in vivo, to the parent active compound. Prodrugs include compounds wherein a hydroxy, amino or mercapto group is bonded to any group that, when the prodrug of the active compound is administered to a subject, cleaves to form a free hydroxy, free amino or free mercapto group, respectively. Examples of prodrugs include, but are not limited to, acetate, formate and benzoate derivatives of an alcohol or acetamide, formamide and benzamide derivatives of an amine functional group in the active compound and the like. Other examples of prodrugs include compounds that comprise —NO, —NO₂, —ONO, or —ONO₂ moieties. Prodrugs can typically be prepared using well-known methods, such as those described in Burger's Medicinal Chemistry and Drug Discovery, 172-178, 949-982 (Manfred E. Wolff ed., 5th ed., 1995), and Design of Prodrugs (H. Bundgaard ed., Elselvier, N.Y., 1985).

For example, if a disclosed compound or a pharmaceutically acceptable form of the compound contains a carboxylic acid functional group, a prodrug can comprise a pharmaceutically acceptable ester formed by the replacement of the hydrogen atom of the acid group with a group such as (C₁-C₈)alkyl, (C₂-C₁₂)alkanoyloxymethyl, 1-(alkanoyloxy)ethyl having from 4 to 9 carbon atoms, 1-methyl-1-(alkanoyloxy)-ethyl having from 5 to 10 carbon atoms, alkoxycarbonyloxymethyl having from 3 to 6 carbon atoms, 1-(alkoxycarbonyloxy)ethyl having from 4 to 7 carbon atoms, 1-methyl-1-(alkoxycarbonyloxy)ethyl having from 5 to 8 carbon atoms, N-(alkoxycarbonyl)aminomethyl having from 3 to 9 carbon atoms, 1-(N-(alkoxycarbonyl)amino)ethyl having from 4 to 10 carbon atoms, 3-phthalidyl, 4-crotonolactonyl, gamma-butyrolacton-4-yl, di-N,N—(C₁-C₂)alkylamino(C₂-C₃)alkyl (such as (3-dimethylaminoethyl), carbamoyl-(C₁-C₂)alkyl, N,N-di(C₁-C₂)alkylcarbamoyl-(C₁-C₂)alkyl and piperidino-, pyrrolidino- or morpholino(C₂-C₃)alkyl.

Similarly, if a disclosed compound or a pharmaceutically acceptable form of the compound contains an alcohol functional group, a prodrug can be formed by the replacement of the hydrogen atom of the alcohol group with a group such as (C₁-C₆)alkanoyloxymethyl, 1-((C₁-C₆)alkanoyloxy)ethyl, 1-methyl-1-((C₁-C₆)alkanoyloxy)ethyl (C₁-C₆)alkoxycarbonyloxymethyl, N—(C₁-C₆)alkoxycarbonylaminomethyl, succinoyl, (C₁-C₆)alkanoyl, α-amino(C₁-C₄)alkanoyl, arylacyl and α-aminoacyl, or α-aminoacyl-α-aminoacyl, where each α-aminoacyl group is independently selected from the naturally occurring L-amino acids, P(O)(OH)₂, —P(O)(O(C₁-C₆)alkyl)₂ or glycosyl (the radical resulting from the removal of a hydroxyl group of the hemiacetal form of a carbohydrate).

If a disclosed compound or a pharmaceutically acceptable form of the compound incorporates an amine functional group, a prodrug can be formed by the replacement of a hydrogen atom in the amine group with a group such as R-carbonyl, RO-carbonyl, NRR′-carbonyl where R and R′ are each independently (C₁-C₁₀)alkyl, (C₃-C₇)cycloalkyl, benzyl, a natural α-aminoacyl or natural α-aminoacyl-natural α-aminoacyl, —C(OH)C(O)OY¹ wherein Y¹ is H, (C₁-C₆)alkyl or benzyl, —C(OY²)Y³ wherein Y² is (C₁-C₄) alkyl and Y³ is (C₁-C₆)alkyl, carboxy(C₁-C₆)alkyl, amino(C₁-C₄)alkyl or mono-N— or di-N,N—(C₁-C₆)alkylaminoalkyl, —C(Y⁴)Y⁵ wherein Y⁴ is H or methyl and Y⁵ is mono-N— or di-N,N—(C₁-C₆)alkylamino, morpholino, piperidin-1-yl or pyrrolidin-1-yl.

In certain embodiments, the pharmaceutically acceptable form is an isomer. “Isomers” are different compounds that have the same molecular formula. “Stereoisomers” are isomers that differ only in the way the atoms are arranged in space. As used herein, the term “isomer” includes any and all geometric isomers and stereoisomers. For example, “isomers” include geometric double bond cis- and trans-isomers, also termed E- and Z-isomers; R- and S-enantiomers; diastereomers, (d)-isomers and (l)-isomers, racemic mixtures thereof; and other mixtures thereof, as falling within the scope of this disclosure.

Geometric isomers can be represented by the symbol which denotes a bond that can be a single, double or triple bond as described herein. Provided herein are various geometric isomers and mixtures thereof resulting from the arrangement of substituents around a carbon-carbon double bond or arrangement of substituents around a carbocyclic ring. Substituents around a carbon-carbon double bond are designated as being in the “Z” or “E” configuration wherein the terms “Z” and “E” are used in accordance with IUPAC standards. Unless otherwise specified, structures depicting double bonds encompass both the “E” and “Z” isomers.

Substituents around a carbon-carbon double bond alternatively can be referred to as “cis” or “trans,” where “cis” represents substituents on the same side of the double bond and “trans” represents substituents on opposite sides of the double bond. The arrangement of substituents around a carbocyclic ring can also be designated as “cis” or “trans.” The term “cis” represents substituents on the same side of the plane of the ring, and the term “trans” represents substituents on opposite sides of the plane of the ring. Mixtures of compounds wherein the substituents are disposed on both the same and opposite sides of plane of the ring are designated “cis/trans.”

“Enantiomers” are a pair of stereoisomers that are non-superimposable mirror images of each other. A mixture of a pair of enantiomers in any proportion can be known as a “racemic” mixture. The term “(±)” is used to designate a racemic mixture where appropriate. “Diastereoisomers” are stereoisomers that have at least two asymmetric atoms, but which are not mirror-images of each other. The absolute stereochemistry is specified according to the Cahn-Ingold-Prelog R-S system. When a compound is an enantiomer, the stereochemistry at each chiral carbon can be specified by either R or S. Resolved compounds whose absolute configuration is unknown can be designated (+) or (−) depending on the direction (dextro- or levorotatory) which they rotate plane polarized light at the wavelength of the sodium D line. Certain of the compounds described herein contain one or more asymmetric centers and can thus give rise to enantiomers, diastereomers, and other stereoisomeric forms that can be defined, in terms of absolute stereochemistry at each asymmetric atom, as (R)- or (S)-. The chemical entities, pharmaceutical compositions and methods described herein are meant to include all such possible isomers, including racemic mixtures, optically substantially pure forms and intermediate mixtures. Optically active (R)- and (S)-isomers can be prepared, for example, using chiral synthons or chiral reagents, or resolved using conventional techniques.

The “enantiomeric excess” or “% enantiomeric excess” of a composition can be calculated using the equation shown below. In the example shown below, a composition contains 90% of one enantiomer, e.g., the S enantiomer, and 10% of the other enantiomer, e.g., the R enantiomer.ee=(90−10)/100=80%

Thus, a composition containing 90% of one enantiomer and 10% of the other enantiomer is said to have an enantiomeric excess of 80%. Some compositions described herein contain an enantiomeric excess of at least about 50%, 75%, 90%, 95%, or 99% of the S enantiomer. In other words, the compositions contain an enantiomeric excess of the S enantiomer over the R enantiomer. In other embodiments, some compositions described herein contain an enantiomeric excess of at least about 50%, 75%, 90%, 95%, or 99% of the R enantiomer. In other words, the compositions contain an enantiomeric excess of the R enantiomer over the S enantiomer.

For instance, an isomer/enantiomer can, in some embodiments, be provided substantially free of the corresponding isomer/enantiomer, and can also be referred to as “optically enriched,” “enantiomerically enriched,” “enantiomerically pure” and “non-racemic,” as used interchangeably herein. These terms refer to compositions in which the percent by weight of one enantiomer is greater than the amount of that one enantiomer in a control mixture of the racemic composition (e.g., greater than 1:1 by weight). For example, an enantiomerically enriched preparation of the S enantiomer, means a preparation of the compound having greater than about 50% by weight of the S enantiomer relative to the R enantiomer, such as at least about 75% by weight, further such as at least about 80% by weight. In some embodiments, the enrichment can be much greater than about 80% by weight, providing a “substantially enantiomerically enriched,” “substantially enantiomerically pure” or a “substantially non-racemic” preparation, which refers to preparations of compositions which have at least about 85% by weight of one enantiomer relative to other enantiomer, such as at least about 90% by weight, and further such as at least 95% by weight. In certain embodiments, the compound provided herein is made up of at least about 90% by weight of one enantiomer. In other embodiments, the compound is made up of at least about 95%, 98%, or 99% by weight of one enantiomer.

In some embodiments, the compound is a racemic mixture of (S)- and (R)-isomers. In other embodiments, provided herein is a mixture of compounds wherein individual compounds of the mixture exist predominately in an (S)- or (R)-isomeric configuration. For example, the compound mixture has an (S)-enantiomeric excess of greater than about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, about 96%, about 97%, about 98%, about 99%, about 99.5%, or more. In other embodiments, the compound mixture has an (S)-enantiomeric excess of greater than about 55% to about 99.5%, greater than about 60% to about 99.5%, greater than about 65% to about 99.5%, greater than about 70% to about 99.5%, greater than about 75% to about 99.5%, greater than about 80% to about 99.5%, greater than about 85% to about 99.5%, greater than about 90% to about 99.5%, greater than about 95% to about 99.5%, greater than about 96% to about 99.5%, greater than about 97% to about 99.5%, greater than about 98% to greater than about 99.5%, greater than about 99% to about 99.5%, or more.

In other embodiments, the compound mixture has an (R)-enantiomeric purity of greater than about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, about 96%, about 97%, about 98%, about 99%, about 99.5% or more. In some other embodiments, the compound mixture has an (R)-enantiomeric excess of greater than about 55% to about 99.5%, greater than about 60% to about 99.5%, greater than about 65% to about 99.5%, greater than about 70% to about 99.5%, greater than about 75% to about 99.5%, greater than about 80% to about 99.5%, greater than about 85% to about 99.5%, greater than about 90% to about 99.5%, greater than about 95% to about 99.5%, greater than about 96% to about 99.5%, greater than about 97% to about 99.5%, greater than about 98% to greater than about 99.5%, greater than about 99% to about 99.5% or more.

In other embodiments, the compound mixture contains identical chemical entities except for their stereochemical orientations, namely (S)- or (R)-isomers. For example, if a compound disclosed herein has —CH(R)— unit, and R is not hydrogen, then the —CH(R)— is in an (S)- or (R)-stereochemical orientation for each of the identical chemical entities. In some embodiments, the mixture of identical chemical entities is a racemic mixture of (S)- and (R)-isomers. In another embodiment, the mixture of the identical chemical entities (except for their stereochemical orientations), contain predominately (S)-isomers or predominately (R)-isomers. For example, the (S)-isomers in the mixture of identical chemical entities are present at about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, about 96%, about 97%, about 98%, about 99%, about 99.5%, or more, relative to the (R)-isomers. In some embodiments, the (S)-isomers in the mixture of identical chemical entities are present at an (S)-enantiomeric excess of greater than about 55% to about 99.5%, greater than about 60% to about 99.5%, greater than about 65% to about 99.5%, greater than about 70% to about 99.5%, greater than about 75% to about 99.5%, greater than about 80% to about 99.5%, greater than about 85% to about 99.5%, greater than about 90% to about 99.5%, greater than about 95% to about 99.5%, greater than about 96% to about 99.5%, greater than about 97% to about 99.5%, greater than about 98% to greater than about 99.5%, greater than about 99% to about 99.5% or more.

In another embodiment, the (R)-isomers in the mixture of identical chemical entities (except for their stereochemical orientations), are present at about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, about 96%, about 97%, about 98%, about 99%, about 99.5%, or more, relative to the (S)-isomers. In some embodiments, the (R)-isomers in the mixture of identical chemical entities (except for their stereochemical orientations), are present at a (R)-enantiomeric excess greater than about 55% to about 99.5%, greater than about 60% to about 99.5%, greater than about 65% to about 99.5%, greater than about 70% to about 99.5%, greater than about 75% to about 99.5%, greater than about 80% to about 99.5%, greater than about 85% to about 99.5%, greater than about 90% to about 99.5%, greater than about 95% to about 99.5%, greater than about 96% to about 99.5%, greater than about 97% to about 99.5%, greater than about 98% to greater than about 99.5%, greater than about 99% to about 99.5%, or more.

Enantiomers can be isolated from racemic mixtures by any method known to those skilled in the art, including chiral high pressure liquid chromatography (HPLC), the formation and crystallization of chiral salts, or prepared by asymmetric syntheses. See, for example, Enantiomers, Racemates and Resolutions (Jacques, Ed., Wiley Interscience, New York, 1981); Wilen et al., Tetrahedron 33:2725 (1977); Stereochemistry of Carbon Compounds (E. L. Eliel, Ed., McGraw-Hill, NY, 1962); and Tables of Resolving Agents and Optical Resolutions p. 268 (E. L. Eliel, Ed., Univ. of Notre Dame Press, Notre Dame, Ind. 1972).

The term “asymmetric center” refers to a tetrahedral carbon atom substituted by four different groups. The term “chiral” refers to a molecule or complex having at least one asymmetric center, or otherwise lacking an internal plane or center of symmetry, and thus having a non-superimposable mirror image. In certain embodiments, the term “chiral” refers to a molecule or complex having at least one asymmetric center. The term “achiral” refers to a molecule or complex having at least one of a plane of symmetry or a center of symmetry. In certain embodiments, the term “achiral” refers to a molecule or complex having no asymmetric centers.

In certain embodiments, the pharmaceutically acceptable form is a tautomer. As used herein, the term “tautomer” is a type of isomer that includes two or more interconvertable compounds resulting from at least one formal migration of a hydrogen atom and at least one change in valency (e.g., a single bond to a double bond, a triple bond to a single bond, or vice versa). “Tautomerization” includes prototropic or proton-shift tautomerization, which is considered a subset of acid-base chemistry. “Prototropic tautomerization” or “proton-shift tautomerization” involves the migration of a proton accompanied by changes in bond order. The exact ratio of the tautomers depends on several factors, including temperature, solvent, and pH. Where tautomerization is possible (e.g., in solution), a chemical equilibrium of tautomers can be reached. Tautomerizations (i.e., the reaction providing a tautomeric pair) can be catalyzed by acid or base, or can occur without the action or presence of an external agent. Exemplary tautomerizations include, but are not limited to, keto-to-enol; amide-to-imide; lactam-to-lactim; enamine-to-imine; and enamine-to-(a different) enamine tautomerizations. A specific example of keto-enol tautomerization is the interconversion of pentane-2,4-dione and 4-hydroxypent-3-en-2-one tautomers. Another example of tautomerization is phenol-keto tautomerization. A specific example of phenol-keto tautomerization is the interconversion of pyridin-4-ol and pyridin-4(1H)-one tautomers.

Unless otherwise stated, structures depicted herein are also meant to include compounds which differ only in the presence of one or more isotopically enriched atoms. For example, compounds having the present structures except for the replacement of a hydrogen by a deuterium or tritium, or the replacement of a carbon by ¹³C- or ¹⁴C-enriched carbon are within the scope of this disclosure.

The disclosure also embraces isotopically labeled compounds which are identical to those recited herein, except that one or more atoms are replaced by an atom having an atomic mass or mass number different from the atomic mass or mass number usually found in nature. Examples of isotopes that can be incorporated into disclosed compounds include isotopes of hydrogen, carbon, nitrogen, oxygen, phosphorus, fluorine and chlorine, such as ²H, ³H, ¹³C, ¹⁴C, ¹⁵N, ¹⁸O, ¹⁷O, ³¹P, ³²P, ³⁵S, ¹⁸F, and ³⁶Cl, respectively. Certain isotopically-labeled disclosed compounds (e.g., those labeled with ³H and ¹⁴C) are useful in compound and/or substrate tissue distribution assays. Tritiated (i.e., ³H) and carbon-14 (i.e., ¹⁴C) isotopes can allow for ease of preparation and detectability. Further, substitution with heavier isotopes such as deuterium (i.e., ²H) can afford certain therapeutic advantages resulting from greater metabolic stability (e.g., increased in vivo half-life or reduced dosage requirements). Isotopically labeled disclosed compounds can generally be prepared by substituting an isotopically labeled reagent for a non-isotopically labeled reagent. In some embodiments, provided herein are compounds that can also contain unnatural proportions of atomic isotopes at one or more of atoms that constitute such compounds. All isotopic variations of the compounds as disclosed herein, whether radioactive or not, are encompassed within the scope of the present disclosure.

Carbon atoms, unless otherwise specified, may optionally be substituted with one or more substituents. The number of substituents is typically limited by the number of available valences on the carbon atom, and may be substituted by replacement of one or more of the hydrogen atoms that would be available on the unsubstituted group. Suitable substituents are known in the art and include, but are not limited to, alkyl, alkenyl, alkynyl, alkoxy, alkoxy, aryl, aryloxy, arylthio, aralkyl, heteroaryl, heteroaralkyl, cycloalkyl, heterocyclyl, halo, azido, hydroxyl, thio, alkthiooxy, amino, nitro, nitrile, imino, amido, carboxylic acid, aldehyde, carbonyl, ester, silyl, alkylthio, haloalkoxy (e.g., perfluoroalkyl such as —CF₃), ═O, ═S, and the like.

When a range of values is listed, it is intended to encompass each value and sub-range within the range. For example, an alkyl group containing 1-6 carbon atoms (C_1-6 alkyl) is intended to encompass, C₁, C₂, C₃, C₄, C₅, C₆, C_1-6, C_2-6, C_3-6, C_4-6, C_5-6, C_1-5, C_2-5, C_3-5, C_4-5, C_1-4, C_2-4, C_3-4, C_1-3, C_2-3, and C_1-2 alkyl.

The term “alkyl,” as used herein, refers to saturated, straight- or branched-chain hydrocarbon radical containing between one and thirty carbon atoms. In certain embodiments, the alkyl group contains 1-20 carbon atoms. Alkyl groups, unless otherwise specified, may optionally be substituted with one or more substituents. In certain embodiments, the alkyl group contains 1-10 carbon atoms. In certain embodiments, the alkyl group contains 1-6 carbon atoms. In certain embodiments, the alkyl group contains 1-5 carbon atoms. In certain embodiments, the alkyl group contains 1-4 carbon atoms. In certain embodiments, the alkyl group contains 1-3 carbon atoms. In certain embodiments, the alkyl group contains 1-2 carbon atoms. In certain embodiments, the alkyl group contains 1 carbon atom. Representative saturated straight chain alkyls include, but are not limited to, -methyl, -ethyl, -n-propyl, -n-butyl, -n-pentyl, and -n-hexyl; while saturated branched alkyls include, but are not limited to, -isopropyl, -sec-butyl, -isobutyl, -tert-butyl, -isopentyl, 2-methylbutyl, 3-methylbutyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 2-methylhexyl, 3-methylhexyl, 4-methylhexyl, 5-methylhexyl, 2,3-dimethylbutyl, and the like. The alkyl is attached to the parent molecule by a single bond. Unless stated otherwise in the specification, an alkyl group is optionally substituted by one or more of substituents which independently include: acyl, alkyl, alkenyl, alkynyl, alkoxy, alkylaryl, cycloalkyl, aralkyl, aryl, aryloxy, amino, amido, amidino, imino, azide, carbonate, carbamate, carbonyl, heteroalkyl, heteroaryl, heteroarylalkyl, heterocycloalkyl, hydroxy, cyano, halo, haloalkoxy, haloalkyl, ester, ether, mercapto, thio, alkylthio, arylthio, thiocarbonyl, nitro, oxo, phosphate, phosphonate, phosphinate, silyl, sulfinyl, sulfonyl, sulfonamidyl, sulfoxyl, sulfonate, urea, —Si(R^a)₃—, —OR^a, —SR^a, —OC(O)—R^a, —N(R^a)₂, —C(O)R^a, —C(O)OR^a, —OC(O)N(R^a)₂, —C(O)N(R^a)₂, —N(R^a)C(O)OR^a, —N(R^a)C(O)R^a, —N(R^a)C(O)N(R^a)₂, —N(R^a)C(NR^a)N(R^a)₂, —N(R^a)S(O)_tR^a (where t is 1 or 2), —S(O)_tOR^a (where t is 1 or 2), —S(O)_tN(R^a)₂ (where t is 1 or 2), or —O—P(═O)(OR^a)₂ where each R^a is independently hydrogen, alkyl, haloalkyl, carbocyclyl, carbocyclylalkyl, aryl, aralkyl, heterocycloalkyl, heterocycloalkylalkyl, heteroaryl or heteroarylalkyl, and each of these moieties can be optionally substituted as defined herein.

“Perhaloalkyl” refers to an alkyl group in which all of the hydrogen atoms have been replaced with a halogen selected from fluoro, chloro, bromo, and iodo. In some embodiments, all of the hydrogen atoms are each replaced with fluoro. In some embodiments, all of the hydrogen atoms are each replaced with chloro. Examples of perhaloalkyl groups include —CF₃, —CF₂CF₃, —CF₂CF₂CF₃, —CCl₃, —CFCl₂, —CF₂Cl and the like.

“Alkyl-cycloalkyl” refers to an -(alkyl)cycloalkyl radical where alkyl and cycloalkyl are as disclosed herein and which are optionally substituted by one or more of the substituents described as suitable substituents for alkyl and cycloalkyl respectively. The “alkyl-cycloalkyl” is bonded to the parent molecular structure through the alkyl group. The terms “alkenyl-cycloalkyl” and “alkynyl-cycloalkyl” mirror the above description of “alkyl-cycloalkyl” wherein the term “alkyl” is replaced with “alkenyl” or “alkynyl” respectively, and “alkenyl” or “alkynyl” are as described herein.

“Alkylaryl” refers to an -(alkyl)aryl radical where aryl and alkyl are as disclosed herein and which are optionally substituted by one or more of the substituents described as suitable substituents for aryl and alkyl respectively. The “alkylaryl” is bonded to the parent molecular structure through the alkyl group. The terms “-(alkenyl)aryl” and “-(alkynyl)aryl” mirror the above description of “-(alkyl)aryl” wherein the term “alkyl” is replaced with “alkenyl” or “alkynyl” respectively, and “alkenyl” or “alkynyl” are as described herein.

“Alkyl-heteroaryl” refers to an -(alkyl)heteroaryl radical where heteroaryl and alkyl are as disclosed herein and which are optionally substituted by one or more of the substituents described as suitable substituents for heteroaryl and alkyl respectively. The “alkyl-heteroaryl” is bonded to the parent molecular structure through the alkyl group. The terms “-(alkenyl)heteroaryl” and “-(alkynyl)heteroaryl” mirror the above description of “-(alkyl)heteroaryl” wherein the term “alkyl” is replaced with “alkenyl” or “alkynyl” respectively, and “alkenyl” or “alkynyl” are as described herein.

“Alkyl-heterocyclyl” refers to an -(alkyl)heterocycyl radical where alkyl and heterocyclyl are as disclosed herein and which are optionally substituted by one or more of the substituents described as suitable substituents for heterocyclyl and alkyl respectively. The “alkyl-heterocyclyl” is bonded to the parent molecular structure through the alkyl group. The terms “-(alkenyl)heterocyclyl” and “-(alkynyl)heterocyclyl” mirror the above description of “-(alkyl)heterocyclyl” wherein the term “alkyl” is replaced with “alkenyl” or “alkynyl” respectively, and “alkenyl” or “alkynyl” are as described herein.

The term “alkenyl,” as used herein, denotes a straight- or branched-chain hydrocarbon radical having at least one carbon-carbon double bond by the removal of a single hydrogen atom, and containing between two and thirty carbon atoms. Alkenyl groups, unless otherwise specified, may optionally be substituted with one or more substituents. In certain embodiments, the alkenyl group contains 2-20 carbon atoms. In certain embodiments, the alkenyl group contains 2-10 carbon atoms. In certain embodiments, the alkenyl group contains 2-6 carbon atoms. In certain embodiments, the alkenyl group contains 2-5 carbon atoms. In certain embodiments, the alkenyl group contains 2-4 carbon atoms. In certain embodiment, the alkenyl group contains 2-3 carbon atoms. In certain embodiments, the alkenyl group contains 2 carbon atoms. The alkenyl is attached to the parent molecular structure by a single bond, for example, ethenyl (i.e., vinyl), prop-1-enyl (i.e., allyl), but-1-enyl, pent-1-enyl, penta-1,4-dienyl, and the like. The one or more carbon-carbon double bonds can be internal (such as in 2-butenyl) or terminal (such as in 1-butenyl). Examples of C_2-4 alkenyl groups include ethenyl (C₂), 1-propenyl (C₃), 2-propenyl (C₃), 1-butenyl (C₄), 2-butenyl (C₄), butadienyl (C₄) and the like. Examples of C_2-6 alkenyl groups include the aforementioned C_2-4 alkenyl groups as well as pentenyl (C₅), pentadienyl (C₅), hexenyl (C₆) and the like. Additional examples of alkenyl include heptenyl (C₇), octenyl (C₈), octatrienyl (C₈) and the like. Unless stated otherwise in the specification, an alkenyl group is optionally substituted by one or more substituents which independently include: acyl, alkyl, alkenyl, alkynyl, alkoxy, alkylaryl, cycloalkyl, aralkyl, aryl, aryloxy, amino, amido, amidino, imino, azide, carbonate, carbamate, carbonyl, heteroalkyl, heteroaryl, heteroarylalkyl, heterocycloalkyl, hydroxy, cyano, halo, haloalkoxy, haloalkyl, ester, ether, mercapto, thio, alkylthio, arylthio, thiocarbonyl, nitro, oxo, phosphate, phosphonate, phosphinate, silyl, sulfinyl, sulfonyl, sulfonamidyl, sulfoxyl, sulfonate, urea, —Si(R^a)₃—, —OR^a, —SR^a, —OC(O)—R^a, —N(R^a)₂, —C(O)R^a, —C(O)OR^a, —OC(O)N(R^a)₂, —C(O)N(R^a)₂, —N(R^a)C(O)OR^a, —N(R^a)C(O)R^a, —N(R^a)C(O)N(R^a)₂, N(R^a)C(NR^a)N(R^a)₂, —N(R^a)S(O)_tR^a (where t is 1 or 2), —S(O)_tOR^a (where t is 1 or 2), —S(O)_tN(R^a)₂ (where t is 1 or 2), or —O—P(═O)(OR^a)₂ where each R^a is independently hydrogen, alkyl, haloalkyl, carbocyclyl, carbocyclylalkyl, aryl, aralkyl, heterocycloalkyl, heterocycloalkylalkyl, heteroaryl or heteroarylalkyl, and each of these moieties can be optionally substituted as defined herein.

The term “alkynyl,” as used herein, denotes a straight- or branched-chain hydrocarbon radical having at least one carbon-carbon triple bond by the removal of a single hydrogen atom, and containing between two and thirty carbon atoms. Alkynyl groups, unless otherwise specified, may optionally be substituted with one or more substituents. In certain embodiments, the alkynyl group contains 2-20 carbon atoms. In certain embodiments, the alkynyl group contains 2-10 carbon atoms. In certain embodiments, the alkynyl group contains 2-6 carbon atoms. In certain embodiments, the alkynyl group contains 2-5 carbon atoms. In certain embodiments, the alkynyl group contains 2-4 carbon atoms. In certain embodiments, the alkynyl group contains 2-3 carbon atoms. In certain embodiments, the alkynyl group contains 2 carbon atoms. The alkynyl is attached to the parent molecular structure by a single bond, for example, ethynyl, propynyl, butynyl, pentynyl, hexynyl, and the like. Unless stated otherwise in the specification, an alkynyl group is optionally substituted by one or more substituents which independently include: acyl, alkyl, alkenyl, alkynyl, alkoxy, alkylaryl, cycloalkyl, aralkyl, aryl, aryloxy, amino, amido, amidino, imino, azide, carbonate, carbamate, carbonyl, heteroalkyl, heteroaryl, heteroarylalkyl, heterocycloalkyl, hydroxy, cyano, halo, haloalkoxy, haloalkyl, ester, ether, mercapto, thio, alkylthio, arylthio, thiocarbonyl, nitro, oxo, phosphate, phosphonate, phosphinate, silyl, sulfinyl, sulfonyl, sulfonamidyl, sulfoxyl, sulfonate, urea, —Si(R^a)₃—, —OR^a, —SR^a, —OC(O)—R^a, —N(R^a)₂, —C(O)R^a, —C(O)OR^a, —OC(O)N(R^a)₂, —C(O)N(R^a)₂, —N(R^a)C(O)OR^a, —N(R^a)C(O)R^a, —N(R^a)C(O)N(R^a)₂, N(R^a)C(NR^a)N(R^a)₂, —N(R^a)S(O)_tR^a (where t is 1 or 2), —S(O)_tOR^a (where t is 1 or 2), —S(O)_tN(R^a)₂ (where t is 1 or 2), or —O—P(═O)(OR^a)₂ where each R^a is independently hydrogen, alkyl, haloalkyl, carbocyclyl, carbocyclylalkyl, aryl, aralkyl, heterocycloalkyl, heterocycloalkylalkyl, heteroaryl or heteroarylalkyl, and each of these moieties can be optionally substituted as defined herein.

The term “alkoxy” refers to the group —O-alkyl, including from 1 to 30 carbon atoms of a straight, branched, cyclic configuration and combinations thereof, attached to the parent molecular structure through an oxygen. Examples include methoxy, ethoxy, propoxy, isopropoxy, cyclopropyloxy, cyclohexyloxy and the like. “Lower alkoxy” refers to alkoxy groups containing one to six carbons. In some embodiments, C₁-C₄ alkoxy is an alkoxy group which encompasses both straight and branched chain alkyls of from 1 to 4 carbon atoms. Unless stated otherwise in the specification, an alkoxy group is optionally substituted by one or more substituents which independently include: acyl, alkyl, alkenyl, alkynyl, alkoxy, alkylaryl, cycloalkyl, aralkyl, aryl, aryloxy, amino, amido, amidino, imino, azide, carbonate, carbamate, carbonyl, heteroalkyl, heteroaryl, heteroarylalkyl, heterocycloalkyl, hydroxy, cyano, halo, haloalkoxy, haloalkyl, ester, ether, mercapto, thio, alkylthio, arylthio, thiocarbonyl, nitro, oxo, phosphate, phosphonate, phosphinate, silyl, sulfinyl, sulfonyl, sulfonamidyl, sulfoxyl, sulfonate, urea, —Si(R^a)_3-, —OR^a, —SR^a, —OC(O)—R^a, —N(R^a)₂, —C(O)R^a, —C(O)OR^a, —OC(O)N(R^a)₂, —C(O)N(R^a)₂, —N(R^a)C(O)OR^a, —N(R^a)C(O)R^a, —N(R^a)C(O)N(R^a)₂, N(R^a)C(NR^a)N(R^a)₂, —N(R^a)S(O)_tR^a (where t is 1 or 2), —S(O)_tOR^a (where t is 1 or 2), —S(O)_tN(R^a)₂ (where t is 1 or 2), or —O—P(═O)(OR^a)₂ where each R^a is independently hydrogen, alkyl, haloalkyl, carbocyclyl, carbocyclylalkyl, aryl, aralkyl, heterocycloalkyl, heterocycloalkylalkyl, heteroaryl or heteroarylalkyl, and each of these moieties can be optionally substituted as defined herein. The terms “alkenoxy” and “alkynoxy” mirror the above description of “alkoxy” wherein the prefix “alk” is replaced with “alken” or “alkyn” respectively, and the parent “alkenyl” or “alkynyl” terms are as described herein.

The term “alkoxycarbonyl” refers to a group of the formula (alkoxy)(C═O)— attached to the parent molecular structure through the carbonyl carbon having from 1 to 30 carbon atoms. Thus a C₁-C₆ alkoxycarbonyl group is an alkoxy group having from 1 to 6 carbon atoms attached through its oxygen to a carbonyl linker. The C₁-C₆ designation does not include the carbonyl carbon in the atom count. “Lower alkoxycarbonyl” refers to an alkoxycarbonyl group wherein the alkyl portion of the alkoxy group is a lower alkyl group. In some embodiments, C₁-C₄ alkoxy is an alkoxy group which encompasses both straight and branched chain alkoxy groups of from 1 to 4 carbon atoms. Unless stated otherwise in the specification, an alkoxycarbonyl group is optionally substituted by one or more substituents which independently include: acyl, alkyl, alkenyl, alkynyl, alkoxy, alkylaryl, cycloalkyl, aralkyl, aryl, aryloxy, amino, amido, amidino, imino, azide, carbonate, carbamate, carbonyl, heteroalkyl, heteroaryl, heteroarylalkyl, heterocycloalkyl, hydroxy, cyano, halo, haloalkoxy, haloalkyl, ester, ether, mercapto, thio, alkylthio, arylthio, thiocarbonyl, nitro, oxo, phosphate, phosphonate, phosphinate, silyl, sulfinyl, sulfonyl, sulfonamidyl, sulfoxyl, sulfonate, urea, —Si(R^a)_3-, —OR^a, —SR^a, —OC(O)—R^a, —N(R^a)₂, —C(O)R^a, —C(O)OR^a, —OC(O)N(R^a)₂, —C(O)N(R^a)₂, —N(R^a)C(O)OR^a, —N(R^a)C(O)R^a, —N(R^a)C(O)N(R^a)₂, N(R^a)C(NR^a)N(R^a)₂, —N(R^a)S(O)_tR^a (where t is 1 or 2), —S(O)_tOR^a (where t is 1 or 2), —S(O)_tN(R^a)₂ (where t is 1 or 2), or —O—P(═O)(OR^a)₂ where each R^a is independently hydrogen, alkyl, haloalkyl, carbocyclyl, carbocyclylalkyl, aryl, aralkyl, heterocycloalkyl, heterocycloalkylalkyl, heteroaryl or heteroarylalkyl, and each of these moieties can be optionally substituted as defined herein. The terms “alkenoxycarbonyl” and “alkynoxycarbonyl” mirror the above description of “alkoxycarbonyl” wherein the prefix “alk” is replaced with “alken” or “alkyn” respectively, and the parent “alkenyl” or “alkynyl” terms are as described herein.

“Acyl” refers to R—C(O)— groups such as, but not limited to, (alkyl)-C(O)—, (alkenyl)-C(O)—, (alkynyl)-C(O)—, (aryl)-C(O)—, (cycloalkyl)-C(O)—, (heteroaryl)-C(O)—, (heteroalkyl)-C(O)—, and (heterocycloalkyl)-C(O)—, wherein the group is attached to the parent molecular structure through the carbonyl functionality. In some embodiments, it is a C₁-C₁₀ acyl radical which refers to the total number of chain or ring atoms of the, for example, alkyl, alkenyl, alkynyl, aryl, cyclohexyl, heteroaryl or heterocycloalkyl portion plus the carbonyl carbon of acyl. For example, a C₄-acyl has three other ring or chain atoms plus carbonyl. If the R radical is heteroaryl or heterocycloalkyl, the hetero ring or chain atoms contribute to the total number of chain or ring atoms. Unless stated otherwise in the specification, the “R” of an acyloxy group can be optionally substituted by one or more substituents which independently include: acyl, alkyl, alkenyl, alkynyl, alkoxy, alkylaryl, cycloalkyl, aralkyl, aryl, aryloxy, amino, amido, amidino, imino, azide, carbonate, carbamate, carbonyl, heteroalkyl, heteroaryl, heteroarylalkyl, heterocycloalkyl, hydroxy, cyano, halo, haloalkoxy, haloalkyl, ester, ether, mercapto, thio, alkylthio, arylthio, thiocarbonyl, nitro, oxo, phosphate, phosphonate, phosphinate, silyl, sulfinyl, sulfonyl, sulfonamidyl, sulfoxyl, sulfonate, urea, —Si(R^a)₃—, —OR^a, —SR^a, —OC(O)—R^a, —N(R^a)₂, —C(O)R^a, —C(O)OR^a, —OC(O)N(R^a)₂, —C(O)N(R^a)₂, —N(R^a)C(O)OR^a, —N(R^a)C(O)R^a, —N(R^a)C(O)N(R^a)₂, N(R^a)C(NR^a)N(R^a)₂, —N(R^a)S(O)_tR^a (where t is 1 or 2), —S(O)_tOR^a (where t is 1 or 2), —S(O)_tN(R^a)₂ (where t is 1 or 2), or —O—P(═O)(OR^a)₂ where each R^a is independently hydrogen, alkyl, haloalkyl, carbocyclyl, carbocyclylalkyl, aryl, aralkyl, heterocycloalkyl, heterocycloalkylalkyl, heteroaryl or heteroarylalkyl, and each of these moieties can be optionally substituted as defined herein.

“Acyloxy” refers to a R(C═O)O— radical wherein “R” can be alkyl, alkenyl, alkynyl, heteroalkyl, heteroalkenyl, heteroalkynyl, aryl, cyclohexyl, heteroaryl or heterocycloalkyl, which are as described herein. The acyloxy group is attached to the parent molecular structure through the oxygen functionality. In some embodiments, an acyloxy group is a C₁-C₄ acyloxy radical which refers to the total number of chain or ring atoms of the alkyl, alkenyl, alkynyl, aryl, cyclohexyl, heteroaryl or heterocycloalkyl portion of the acyloxy group plus the carbonyl carbon of acyl, i.e., a C₄-acyloxy has three other ring or chain atoms plus carbonyl. If the R radical is heteroaryl or heterocycloalkyl, the hetero ring or chain atoms contribute to the total number of chain or ring atoms. Unless stated otherwise in the specification, the “R” of an acyloxy group is optionally substituted by one or more substituents which independently include: acyl, alkyl, alkenyl, alkynyl, alkoxy, alkylaryl, cycloalkyl, aralkyl, aryl, aryloxy, amino, amido, amidino, imino, azide, carbonate, carbamate, carbonyl, heteroalkyl, heteroaryl, heteroarylalkyl, heterocycloalkyl, hydroxy, cyano, halo, haloalkoxy, haloalkyl, ester, ether, mercapto, thio, alkylthio, arylthio, thiocarbonyl, nitro, oxo, phosphate, phosphonate, phosphinate, silyl, sulfinyl, sulfonyl, sulfonamidyl, sulfoxyl, sulfonate, urea, —Si(R^a)₃—, —OR^a, —SR^a, —OC(O)—R^a, —N(R^a)₂, —C(O)R^a, —C(O)OR^a, —OC(O)N(R^a)₂, —C(O)N(R^a)₂, —N(R^a)C(O)OR^a, —N(R^a)C(O)R^a, —N(R^a)C(O)N(R^a)₂, N(R^a)C(NR^a)N(R^a)₂, —N(R^a)S(O)_tR^a (where t is 1 or 2), —S(O)_tOR^a (where t is 1 or 2), —S(O)_tN(R^a)₂ (where t is 1 or 2), or —O—P(═O)(OR^a)₂ where each R^a is independently hydrogen, alkyl, haloalkyl, carbocyclyl, carbocyclylalkyl, aryl, aralkyl, heterocycloalkyl, heterocycloalkylalkyl, heteroaryl or heteroarylalkyl and each of these moieties can be optionally substituted as defined herein.

“Amino” or “amine” refers to a —N(R^b)₂, —N(R^b)R^b—, or —R^bN(R^b)R^b— radical group, where each R^b is independently selected from hydrogen, alkyl, alkenyl, alkynyl, haloalkyl, heteroalkyl (bonded through a chain carbon), cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocycloalkyl (bonded through a ring carbon), heterocycloalkylalkyl, heteroaryl (bonded through a ring carbon) or heteroarylalkyl, unless stated otherwise in the specification, each of which moiety can itself be optionally substituted as described herein. When a —N(R^b)₂ group has two R^b other than hydrogen, they can be combined with the nitrogen atom to form a 3-, 4-, 5-, 6-, or 7-membered ring. For example, —N(R^b)₂ is meant to include, but not be limited to, 1-pyrrolidinyl and 4-morpholinyl. In some embodiments, the term “amino” refers to the group —NR′₂, wherein each R′ is, independently, hydrogen, a carbon moiety, such as, for example, an alkyl, alkenyl, alkynyl, aryl or heteroaryl group, as defined herein, or two R′ groups together with the nitrogen atom to which they are bound form a 5-8 membered ring. Unless stated otherwise in the specification, an amino group is optionally substituted by one or more substituents which independently include: acyl, alkyl, alkenyl, alkynyl, alkoxy, alkylaryl, cycloalkyl, aralkyl, aryl, aryloxy, amino, amido, amidino, imino, azide, carbonate, carbamate, carbonyl, heteroalkyl, heteroaryl, heteroarylalkyl, heterocycloalkyl, hydroxy, cyano, halo, haloalkoxy, haloalkyl, ester, ether, mercapto, thio, alkylthio, arylthio, thiocarbonyl, nitro, oxo, phosphate, phosphonate, phosphinate, silyl, sulfinyl, sulfonyl, sulfonamidyl, sulfoxyl, sulfonate, urea, —Si(R^a)_3-, —OR^a, —SR^a, —OC(O)—R^a, —N(R^a)₂, —C(O)R^a, —C(O)OR^a, —OC(O)N(R^a)₂, —C(O)N(R^a)₂, —N(R^a)C(O)OR^a, —N(R^a)C(O)R^a, —N(R^a)C(O)N(R^a)₂, N(R^a)C(NR^a)N(R^a)₂, —N(R^a)S(O)_tR^a (where t is 1 or 2), —S(O)_tOR^a (where t is 1 or 2), —S(O)_tN(R^a)₂ (where t is 1 or 2), or —O—P(═O)(OR^a)₂ where each R^a is independently hydrogen, alkyl, haloalkyl, carbocyclyl, carbocyclylalkyl, aryl, aralkyl, heterocycloalkyl, heterocycloalkylalkyl, heteroaryl or heteroarylalkyl, and each of these moieties can be optionally substituted as defined herein.

The terms “amine” and “amino” also refer to N-oxides of the groups N+(H)(R^a)O⁻, and —N+(R^a)(R^a)O⁻, R^a as described above, where the N-oxide is bonded to the parent molecular structure through the N atom. N-oxides can be prepared by treatment of the corresponding amino group with, for example, hydrogen peroxide or m-chloroperoxybenzoic acid. The person skilled in the art is familiar with reaction conditions for carrying out the N-oxidation.

“Amide” or “amido” refers to a chemical moiety with formula —C(O)N(R^b)₂ or —NR^bC(O)R^b, where R^b is independently selected from hydrogen, alkyl, alkenyl, alkynyl, haloalkyl, heteroalkyl (bonded through a chain carbon), cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocycloalkyl (bonded through a ring carbon), heterocycloalkylalkyl, heteroaryl (bonded through a ring carbon) or heteroarylalkyl, unless stated otherwise in the specification, each of which moiety can itself be optionally substituted as described herein. In some embodiments, this radical is a C₁-C₄ amido or amide radical, which includes the amide carbonyl in the total number of carbons in the radical. When a —C(O)N(R^b)₂ has two R^b other than hydrogen, they can be combined with the nitrogen atom to form a 3-, 4-, 5-, 6-, 7- or 8-membered ring. For example, the N(R^b)₂ portion of a —C(O)N(R^b)₂ radical is meant to include, but not be limited to, 1-pyrrolidinyl and 4-morpholinyl. In some embodiments, wherein each R′ is, independently, hydrogen or a carbon moiety, such as, for example, an alkyl, alkenyl, alkynyl, aryl or heteroaryl group, as defined herein, or two R′ groups together with the nitrogen atom to which they are bound form a 5-8 membered ring. Unless stated otherwise in the specification, an amido R^b group is optionally substituted by one or more substituents which independently include: acyl, alkyl, alkenyl, alkynyl, alkoxy, alkylaryl, cycloalkyl, aralkyl, aryl, aryloxy, amino, amido, amidino, imino, azide, carbonate, carbamate, carbonyl, heteroalkyl, heteroaryl, heteroarylalkyl, heterocycloalkyl, hydroxy, cyano, halo, haloalkoxy, haloalkyl, ester, ether, mercapto, thio, alkylthio, arylthio, thiocarbonyl, nitro, oxo, phosphate, phosphonate, phosphinate, silyl, sulfinyl, sulfonyl, sulfonamidyl, sulfoxyl, sulfonate, urea, —Si(R^a)₃—, —OR^a, —SR^a, —OC(O)—R^a, —N(R^a)₂, —C(O)R^a, —C(O)OR^a, —OC(O)N(R^a)₂, —C(O)N(R^a)₂, —N(R^a)C(O)OR^a, —N(R^a)C(O)R^a, —N(R^a)C(O)N(R^a)₂, N(R^a)C(NR^a)N(R^a)₂, —N(R^a)S(O)_tR^a (where t is 1 or 2), —S(O)_tOR^a (where t is 1 or 2), —S(O)_tN(R^a)₂ (where t is 1 or 2), or —O—P(═O)(OR^a)₂ where each R^a is independently hydrogen, alkyl, haloalkyl, carbocyclyl, carbocyclylalkyl, aryl, aralkyl, heterocycloalkyl, heterocycloalkylalkyl, heteroaryl or heteroarylalkyl, and each of these moieties can be optionally substituted as defined herein.

The term “amide” or “amido” is inclusive of an amino acid or a peptide molecule. Any amine, hydroxy, or carboxyl side chain on the compounds described herein can be transformed into an amide group. The procedures and specific groups to make such amides are known to those of skill in the art and can readily be found in reference sources such as Greene and Wuts, Protective Groups in Organic Synthesis, 3rd Ed., John Wiley & Sons, New York, N.Y., 1999, which is incorporated herein by reference in its entirety.

“Amidino” refers to both the —C(═NR^b)N(R^b)₂ and —N(R^b)—C(═NR^b)— radicals, where each R^b is independently selected from hydrogen, alkyl, alkenyl, alkynyl, haloalkyl, heteroalkyl (bonded through a chain carbon), cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocycloalkyl (bonded through a ring carbon), heterocycloalkylalkyl, heteroaryl (bonded through a ring carbon) or heteroarylalkyl, unless stated otherwise in the specification, each of which moiety can itself be optionally substituted as described herein.

“Aromatic” or “aryl” refers to a radical with six to ten ring atoms (e.g., C₆-C₁₀ aromatic or C₆-C₁₀ aryl) which has at least one ring having a conjugated pi electron system which is carbocyclic (e.g., phenyl, fluorenyl, and naphthyl). For example, bivalent radicals formed from substituted benzene derivatives and having the free valences at ring atoms are named as substituted phenylene radicals. In other embodiments, bivalent radicals derived from univalent polycyclic hydrocarbon radicals whose names end in “-yl” by removal of one hydrogen atom from the carbon atom with the free valence are named by adding “-idene” to the name of the corresponding univalent radical, e.g., a naphthyl group with two points of attachment is termed naphthylidene. Whenever it appears herein, a numerical range such as “6 to 10 aryl” refers to each integer in the given range; e.g., “6 to 10 ring atoms” means that the aryl group can consist of 6 ring atoms, 7 ring atoms, etc., up to and including 10 ring atoms. The term includes monocyclic or fused-ring polycyclic (i.e., rings which share adjacent pairs of ring atoms) groups. In certain embodiments of the present invention, “aryl” refers to an aromatic ring system which includes, but not limited to, phenyl, biphenyl, naphthyl, anthracyl and the like, which may bear one or more substituents. Also included within the scope of the term “aryl”, as it is used herein, is a group in which an aryl ring is fused to one or more non-aromatic rings, such as indanyl, phthalimidyl or tetrahydronaphthalyl, and the like, where the point of attachment is on the aryl ring. Unless stated otherwise in the specification, an aryl moiety can be optionally substituted by one or more substituents which independently include: acyl, alkyl, alkenyl, alkynyl, alkoxy, alkylaryl, cycloalkyl, aralkyl, aryl, aryloxy, amino, amido, amidino, imino, azide, carbonate, carbamate, carbonyl, heteroalkyl, heteroaryl, heteroarylalkyl, heterocycloalkyl, hydroxy, cyano, halo, haloalkoxy, haloalkyl, ester, ether, mercapto, thio, alkylthio, arylthio, thiocarbonyl, nitro, oxo, phosphate, phosphonate, phosphinate, silyl, sulfinyl, sulfonyl, sulfonamidyl, sulfoxyl, sulfonate, urea, —Si(R^a)₃—, —OR^a, —SR^a, —OC(O)—R^a, —N(R^a)₂, —C(O)R^a, —C(O)OR^a, —OC(O)N(R^a)₂, —C(O)N(R^a)₂, —N(R^a)C(O)OR^a, —N(R^a)C(O)R^a, —N(R^a)C(O)N(R^a)₂, N(R^a)C(NR^a)N(R^a)₂, —N(R^a)S(O)_tR^a (where t is 1 or 2), —S(O)_tOR^a (where t is 1 or 2), —S(O)_tN(R^a)₂ (where t is 1 or 2), or —O—P(═O)(OR^a)₂ where each R^a is independently hydrogen, alkyl, haloalkyl, carbocyclyl, carbocyclylalkyl, aryl, aralkyl, heterocycloalkyl, heterocycloalkylalkyl, heteroaryl or heteroarylalkyl, and each of these moieties can be optionally substituted as defined herein.

“Aralkyl” or “arylalkyl” refers to an (aryl)alkyl-radical where aryl and alkyl are as disclosed herein and which are optionally substituted by one or more of the substituents described as suitable substituents for aryl and alkyl respectively. The “aralkyl/arylalkyl” is bonded to the parent molecular structure through the alkyl group. The terms “aralkenyl/arylalkenyl” and “aralkynyl/arylalkynyl” mirror the above description of “aralkyl/arylalkyl” wherein the “alkyl” is replaced with “alkenyl” or “alkynyl” respectively, and the “alkenyl” or “alkynyl” terms are as described herein.

As used herein, the term “azido” refers to the group —N₃.

“Carbamate” refers to any of the following radicals: —O—(C═O)—N(R^b)—, —O—(C═O)—N(R^b)₂, —N(R^b)—(C═O)—O—, and —N(R^b)—(C═O)—OR^b, wherein each R^b is independently selected from alkyl, alkenyl, alkynyl, haloalkyl, heteroalkyl (bonded through a chain carbon), cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocycloalkyl (bonded through a ring carbon), heterocycloalkylalkyl, heteroaryl (bonded through a ring carbon) or heteroarylalkyl, unless stated otherwise in the specification, each of which moiety can itself be optionally substituted as described herein.

“Carbonate” refers to a —O—(C═O)—O— radical.

“Carbonyl” refers to a —(C═O)— radical. In some embodiments, the term “carbonyl” refers to the group —C(═O)R′, wherein R′ is, independently, a carbon moiety, such as, for example, an alkyl, alkenyl, alkynyl, aryl or heteroaryl group, as defined herein.

“Carboxaldehyde” or “aldehyde” refers to a —(C═O)H radical.

“Carboxyl” refers to a —(C═O)OH radical.

“Cyano” refers to a —CN radical.

“Cycloalkyl” and “carbocyclyl” each refer to a monocyclic or polycyclic radical that contains only carbon and hydrogen, and can be saturated or partially unsaturated. Partially unsaturated cycloalkyl groups can be termed “cycloalkenyl” if the carbocycle contains at least one double bond, or “cycloalkynyl” if the carbocycle contains at least one triple bond. The terms “cycloalkyl” and “carbocyclyl” used alone or as part of a larger moiety, refer to a saturated monocyclic or bicyclic hydrocarbon ring system having from 3-15 carbon ring members. Cycloalkyl groups, unless otherwise specified, may optionally be substituted with one or more substituents. In certain embodiments, cycloalkyl groups contain 3-10 carbon ring members. Whenever it appears herein, a numerical range such as “3-10” refers to each integer in the given range; e.g., “3-10 carbon atoms” means that the cycloalkyl group can consist of 3 carbon atoms, 4 carbon atoms, 5 carbon atoms, etc., up to and including 10 carbon atoms. The term “cycloalkyl” also includes bridged and spiro-fused cyclic structures containing no heteroatoms. In certain embodiments, cycloalkyl groups contain 3-9 carbon ring members. In certain embodiments, cycloalkyl groups contain 3-8 carbon ring members. In certain embodiments, cycloalkyl groups contain 3-7 carbon ring members. In certain embodiments, cycloalkyl groups contain 3-6 carbon ring members. In certain embodiments, cycloalkyl groups contain 3-5 carbon ring members. Cycloalkyl groups include, without limitation, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. The term “cycloalkyl” also includes saturated hydrocarbon ring systems that are fused to one or more aryl or heteroaryl rings, such as decahydronaphthyl or tetrahydronaphthyl, where the point of attachment is on the saturated hydrocarbon ring. Illustrative examples of cycloalkyl groups include, but are not limited to the following moieties: C_3-6 carbocyclyl groups include, without limitation, cyclopropyl (C₃), cyclobutyl (C₄), cyclopentyl (C₅), cyclopentenyl (C₅), cyclohexyl (C₆), cyclohexenyl (C₆), cyclohexadienyl (C₆) and the like. Examples of C_3-8 carbocyclyl groups include the aforementioned C_3-10 carbocyclyl groups as well as cycloheptyl (C₇), cycloheptadienyl (C₇), cycloheptatrienyl (C₇), cyclooctyl (C₈), bicyclo[2.2.1]heptanyl, bicyclo[2.2.2]octanyl, and the like. Examples of C_3-10 carbocyclyl groups include the aforementioned C_3-8 carbocyclyl groups as well as octahydro-1H-indenyl, decahydronaphthalenyl, spiro[4.5]decanyl and the like. Unless stated otherwise in the specification, a cycloalkyl group is optionally substituted by one or more substituents which independently include: acyl, alkyl, alkenyl, alkynyl, alkoxy, alkylaryl, cycloalkyl, aralkyl, aryl, aryloxy, amino, amido, amidino, imino, azide, carbonate, carbamate, carbonyl, heteroalkyl, heteroaryl, heteroarylalkyl, heterocycloalkyl, hydroxy, cyano, halo, haloalkoxy, haloalkyl, ester, ether, mercapto, thio, alkylthio, arylthio, thiocarbonyl, nitro, oxo, phosphate, phosphonate, phosphinate, silyl, sulfinyl, sulfonyl, sulfonamidyl, sulfoxyl, sulfonate, urea, —Si(R^a)₃—, —OR^a, —SR^a, —OC(O)—R^a, —N(R^a)₂, —C(O)R^a, —C(O)OR^a, —OC(O)N(R^a)₂, —C(O)N(R^a)₂, —N(R^a)C(O)OR^a, —N(R^a)C(O)R^a, —N(R^a)C(O)N(R^a)₂, N(R^a)C(NR^a)N(R^a)₂, —N(R^a)S(O)_tR^a (where t is 1 or 2), —S(O)_tOR^a (where t is 1 or 2), —S(O)_tN(R^a)₂ (where t is 1 or 2), or —O—P(═O)(OR^a)₂ where each R^a is independently hydrogen, alkyl, haloalkyl, carbocyclyl, carbocyclylalkyl, aryl, aralkyl, heterocycloalkyl, heterocycloalkylalkyl, heteroaryl or heteroarylalkyl, and each of these moieties can be optionally substituted as defined herein.

“Cycloalkyl-alkyl” refers to a -(cycloalkyl)alkyl radical where cycloalkyl and alkyl are as disclosed herein and which are optionally substituted by one or more of the substituents described as suitable substituents for cycloalkyl and alkyl respectively. The “cycloalkyl-alkyl” is bonded to the parent molecular structure through the cycloalkyl group. The terms “cycloalkyl-alkenyl” and “cycloalkyl-alkynyl” mirror the above description of “cycloalkyl-alkyl” wherein the term “alkyl” is replaced with “alkenyl” or “alkynyl” respectively, and “alkenyl” or “alkynyl” are as described herein.

“Cycloalkyl-heterocycloalkyl” refers to a -(cycloalkyl)heterocycylalkyl radical where cycloalkyl and heterocycloalkyl are as disclosed herein and which are optionally substituted by one or more of the substituents described as suitable substituents for heterocycloalkyl and cycloalkyl respectively. The “cycloalkyl-heterocycloalkyl” is bonded to the parent molecular structure through the cycloalkyl group.

“Cycloalkyl-heteroaryl” refers to a -(cycloalkyl)heteroaryl radical where cycloalkyl and heteroaryl are as disclosed herein and which are optionally substituted by one or more of the substituents described as suitable substituents for heteroaryl and cycloalkyl respectively. The “cycloalkyl-heteroaryl” is bonded to the parent molecular structure through the cycloalkyl group.

As used herein, a “covalent bond” or “direct bond” refers to a single bond joining two groups.

“Ester” refers to the group —C(═O)OR′ or —OC(═O)R′, where R′ is selected from alkyl, alkenyl, alkynyl, haloalkyl, heteroalkyl (bonded through a chain carbon), cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocycloalkyl (bonded through a ring carbon), heterocycloalkylalkyl, heteroaryl (bonded through a ring carbon) or heteroarylalkyl. In some embodiments, each R′ is, independently, a carbon moiety, such as, for example, an alkyl, alkenyl, alkynyl, aryl or heteroaryl group, as defined herein. Any amine, hydroxy, or carboxyl side chain on the compounds described herein can be esterified. The procedures and specific groups to make such esters are known to those of skill in the art and can readily be found in reference sources such as Greene and Wuts, Protective Groups in Organic Synthesis, 3rd Ed., John Wiley & Sons, New York, N.Y., 1999, which is incorporated herein by reference in its entirety. Unless stated otherwise in the specification, an ester group can be optionally substituted by one or more substituents which independently include: acyl, alkyl, alkenyl, alkynyl, alkoxy, alkylaryl, cycloalkyl, aralkyl, aryl, aryloxy, amino, amido, amidino, imino, azide, carbonate, carbamate, carbonyl, heteroalkyl, heteroaryl, heteroarylalkyl, heterocycloalkyl, hydroxy, cyano, halo, haloalkoxy, haloalkyl, ester, ether, mercapto, thio, alkylthio, arylthio, thiocarbonyl, nitro, oxo, phosphate, phosphonate, phosphinate, silyl, sulfinyl, sulfonyl, sulfonamidyl, sulfoxyl, sulfonate, urea, —Si(R^a)₃—, —OR^a, —SR^a, —OC(O)—R^a, —N(R^a)₂, —C(O)R^a, —C(O)OR^a, —OC(O)N(R^a)₂, —C(O)N(R^a)₂, —N(R^a)C(O)OR^a, —N(R^a)C(O)R^a, —N(R^a)C(O)N(R^a)₂, N(R^a)C(NR^a)N(R^a)₂, —N(R^a)S(O)_tR^a (where t is 1 or 2), —S(O)_tOR^a (where t is 1 or 2), —S(O)_tN(R^a)₂ (where t is 1 or 2), or —O—P(═O)(OR^a)₂ where each R^a is independently hydrogen, alkyl, haloalkyl, carbocyclyl, carbocyclylalkyl, aryl, aralkyl, heterocycloalkyl, heterocycloalkylalkyl, heteroaryl or heteroarylalkyl, and each of these moieties can be optionally substituted as defined herein.

“Ether” refers to a —R^b—O—R^b— radical where each R^b is independently selected from hydrogen, alkyl, alkenyl, alkynyl, haloalkyl, heteroalkyl (bonded through a chain carbon), cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocycloalkyl (bonded through a ring carbon), heterocycloalkylalkyl, heteroaryl (bonded through a ring carbon) or heteroarylalkyl, unless stated otherwise in the specification, each of which moiety can itself be optionally substituted as described herein.

“Halo”, “halide”, or, alternatively, “halogen” means fluoro, chloro, bromo or iodo. The terms “haloalkyl,” “haloalkenyl,” “haloalkynyl” and “haloalkoxy” include alkyl, alkenyl, alkynyl and alkoxy structures that are substituted with one or more halo groups or with combinations thereof. For example, the terms “fluoroalkyl” and “fluoroalkoxy” include haloalkyl and haloalkoxy groups, respectively, in which the halo is fluorine, such as, but not limited to, trifluoromethyl, difluoromethyl, 2,2,2-trifluoroethyl, 1-fluoromethyl-2-fluoroethyl, and the like. Each of the alkyl, alkenyl, alkynyl and alkoxy groups are as defined herein and can be optionally further substituted as defined herein.

“Heteroalkyl”, “heteroalkenyl” and “heteroalkynyl” include alkyl, alkenyl and alkynyl radicals, respectively, which have one or more skeletal chain atoms selected from an atom other than carbon, e.g., oxygen, nitrogen, sulfur, phosphorus or combinations thereof. A numerical range can be given, e.g., C₁-C₄ heteroalkyl which refers to the chain length in total, which in this example is 4 atoms long. For example, a —CH₂OCH₂CH₃ radical is referred to as a “C₄” heteroalkyl, which includes the heteroatom center in the atom chain length description. Connection to the parent molecular structure can be through either a heteroatom or a carbon in the heteroalkyl chain. For example, an N-containing heteroalkyl moiety refers to a group in which at least one of the skeletal atoms is a nitrogen atom. One or more heteroatom(s) in the heteroalkyl radical can be optionally oxidized. One or more nitrogen atoms, if present, can also be optionally quaternized. For example, heteroalkyl also includes skeletal chains substituted with one or more nitrogen oxide (—O—) substituents. Exemplary heteroalkyl groups include, without limitation, ethers such as methoxyethanyl (—CH₂CH₂OCH₃), ethoxymethanyl (—CH₂OCH₂CH₃), (methoxymethoxy)ethanyl (—CH₂CH₂OCH₂OCH₃), (methoxymethoxy)methanyl (—CH₂OCH₂OCH₃) and (methoxyethoxy)methanyl (—CH₂OCH₂CH₂OCH₃) and the like; amines such as —CH₂CH₂NHCH₃, —CH₂CH₂N(CH₃)₂, —CH₂NHCH₂CH₃, —CH₂N(CH₂CH₃)(CH₃) and the like. Heteroalkyl, heteroalkenyl, and heteroalkynyl groups can each be optionally substituted by one or more substituents which independently include: acyl, alkyl, alkenyl, alkynyl, alkoxy, alkylaryl, cycloalkyl, aralkyl, aryl, aryloxy, amino, amido, amidino, imino, azide, carbonate, carbamate, carbonyl, heteroalkyl, heteroaryl, heteroarylalkyl, heterocycloalkyl, hydroxy, cyano, halo, haloalkoxy, haloalkyl, ester, ether, mercapto, thio, alkylthio, arylthio, thiocarbonyl, nitro, oxo, phosphate, phosphonate, phosphinate, silyl, sulfinyl, sulfonyl, sulfonamidyl, sulfoxyl, sulfonate, urea, —Si(R^a)₃—, —OR^a, —SR^a, —OC(O)—R^a, —N(R^a)₂, —C(O)R^a, —C(O)OR^a, —OC(O)N(R^a)₂, —C(O)N(R^a)₂, —N(R^a)C(O)OR^a, —N(R^a)C(O)R^a, —N(R^a)C(O)N(R^a)₂, N(R^a)C(NR^a)N(R^a)₂, —N(R^a)S(O)_tR^a (where t is 1 or 2), —S(O)_tOR^a (where t is 1 or 2), —S(O)_tN(R^a)₂ (where t is 1 or 2), or —O—P(═O)(OR^a)₂ where each R^a is independently hydrogen, alkyl, haloalkyl, carbocyclyl, carbocyclylalkyl, aryl, aralkyl, heterocycloalkyl, heterocycloalkylalkyl, heteroaryl or heteroarylalkyl, and each of these moieties can be optionally substituted as defined herein.

“Heteroalkyl-aryl” refers to a -(heteroalkyl)aryl radical where heteroalkyl and aryl are as disclosed herein and which are optionally substituted by one or more of the substituents described as suitable substituents for heteroalkyl and aryl respectively. The “heteroalkyl-aryl” is bonded to the parent molecular structure through an atom of the heteroalkyl group.

“Heteroalkyl-heteroaryl” refers to a -(heteroalkyl)heteroaryl radical where heteroalkyl and heteroaryl are as disclosed herein and which are optionally substituted by one or more of the substituents described as suitable substituents for heteroalkyl and heteroaryl respectively. The “heteroalkyl-heteroaryl” is bonded to the parent molecular structure through an atom of the heteroalkyl group.

“Heteroalkyl-heterocycloalkyl” refers to a -(heteroalkyl)heterocycloalkyl radical where heteroalkyl and heterocycloalkyl are as disclosed herein and which are optionally substituted by one or more of the substituents described as suitable substituents for heteroalkyl and heterocycloalkyl respectively. The “heteroalkyl-heterocycloalkyl” is bonded to the parent molecular structure through an atom of the heteroalkyl group.

“Heteroalkyl-cycloalkyl” refers to a -(heteroalkyl)cycloalkyl radical where heteroalkyl and cycloalkyl are as disclosed herein and which are optionally substituted by one or more of the substituents described as suitable substituents for heteroalkyl and cycloalkyl respectively. The “heteroalkyl-cycloalkyl” is bonded to the parent molecular structure through an atom of the heteroalkyl group.

The term “heteroatom” refers to boron, phosphorus, silicon, selenium, nitrogen, oxygen, or sulfur, and includes any oxidized form of nitrogen or sulfur, and any quaternized form of a basic nitrogen.

“Heteroaryl” or, alternatively, “heteroaromatic” refers to a refers to a radical of a 5-18 membered monocyclic or polycyclic (e.g., bicyclic or tricyclic) aromatic ring system (e.g., having 6, 10 or 14 it electrons shared in a cyclic array) having ring carbon atoms and 1-6 ring heteroatoms provided in the aromatic ring system, wherein each heteroatom is independently selected from nitrogen, oxygen, phosphorous and sulfur (“5-18 membered heteroaryl”). Whenever it appears herein, a numerical range such as “5 to 18” refers to each integer in the given range; e.g., “5 to 18 ring atoms” means that the heteroaryl group can consist of 5 ring atoms, 6 ring atoms, etc., up to and including 18 ring atoms. For example, bivalent radicals derived from univalent heteroaryl radicals whose names end in “-yl” by removal of one hydrogen atom from the atom with the free valence are named by adding “-idene” to the name of the corresponding univalent radical, e.g., a pyridyl group with two points of attachment is a pyridylidene. Heteroaryl polycyclic ring systems can include one or more heteroatoms in one or both rings.

For example, an N-containing “heteroaromatic” or “heteroaryl” moiety refers to an aromatic group in which at least one of the skeletal atoms of the ring is a nitrogen atom. One or more heteroatom(s) in the heteroaryl radical can be optionally oxidized. One or more nitrogen atoms, if present, can also be optionally quaternized. Heteroaryl also includes ring systems substituted with one or more nitrogen oxide (—O—) substituents, such as pyridinyl N-oxides. The heteroaryl is attached to the parent molecular structure through any atom of the ring(s).

“Heteroaryl” also includes ring systems wherein the heteroaryl ring, as defined above, is fused with one or more aryl groups wherein the point of attachment to the parent molecular structure is either on the aryl or on the heteroaryl ring, or wherein the heteroaryl ring, as defined above, is fused with one or more cycloalkyl or heterocycyl groups wherein the point of attachment to the parent molecular structure is on the heteroaryl ring. For polycyclic heteroaryl groups wherein one ring does not contain a heteroatom (e.g., indolyl, quinolinyl, carbazolyl and the like), the point of attachment to the parent molecular structure can be on either ring, i.e., either the ring bearing a heteroatom (e.g., 2-indolyl) or the ring that does not contain a heteroatom (e.g., 5-indolyl). In some embodiments, a heteroaryl group is a 5-10 membered aromatic ring system having ring carbon atoms and 1-4 ring heteroatoms provided in the aromatic ring system, wherein each heteroatom is independently selected from nitrogen, oxygen, phosphorous, and sulfur (“5-10 membered heteroaryl”). In some embodiments, a heteroaryl group is a 5-8 membered aromatic ring system having ring carbon atoms and 1-4 ring heteroatoms provided in the aromatic ring system, wherein each heteroatom is independently selected from nitrogen, oxygen, phosphorous, and sulfur (“5-8 membered heteroaryl”). In some embodiments, a heteroaryl group is a 5-6 membered aromatic ring system having ring carbon atoms and 1-4 ring heteroatoms provided in the aromatic ring system, wherein each heteroatom is independently selected from nitrogen, oxygen, phosphorous, and sulfur (“5-6 membered heteroaryl”). In some embodiments, the 5-6 membered heteroaryl has 1-3 ring heteroatoms selected from nitrogen, oxygen, phosphorous, and sulfur. In some embodiments, the 5-6 membered heteroaryl has 1-2 ring heteroatoms selected from nitrogen, oxygen, phosphorous, and sulfur. In some embodiments, the 5-6 membered heteroaryl has 1 ring heteroatom selected from nitrogen, oxygen, phosphorous, and sulfur.

In some embodiments, the terms “heteroaryl” used alone or as part of a larger moiety, e.g., “heteroaralkyl”, refer to an aromatic monocyclic or bicyclic hydrocarbon ring system having 5-10 ring atoms wherein the ring atoms comprise, in addition to carbon atoms, from one to five heteroatoms. Heteroaryl groups, unless otherwise specified, may optionally be substituted with one or more substituents. When used in reference to a ring atom of a heteroaryl group, the term “nitrogen” includes a substituted nitrogen. Heteroaryl groups include, without limitation, thienyl, furanyl, pyrrolyl, imidazolyl, pyrazolyl, triazolyl, tetrazolyl, oxazolyl, isoxazolyl, oxadiazolyl, thiazolyl, isothiazolyl, thiadiazolyl, pyridyl, pyridazinyl, pyrimidinyl, pyrazinyl, indolizinyl, purinyl, naphthyridinyl, and pteridinyl. The terms “heteroaryl” and “heteroar-”, as used herein, also include groups in which a heteroaryl ring is fused to one or more aryl, cycloalkyl or heterocycloalkyl rings, wherein the point of attachment is on the heteroaryl ring. Nonlimiting examples include indolyl, isoindolyl, benzothienyl, benzofuranyl, dibenzofuranyl, indazolyl, benzimidazolyl, benzthiazolyl, quinolyl, isoquinolyl, cinnolinyl, phthalazinyl, quinazolinyl, quinoxalinyl, 4H-quinolizinyl, carbazolyl, acridinyl, phenazinyl, phenothiazinyl, phenoxazinyl, tetrahydroquinolinyl, and tetrahydroisoquinolinyl.

Examples of heteroaryls include, but are not limited to, azepinyl, acridinyl, benzimidazolyl, benzindolyl, 1,3-benzodioxolyl, benzofuranyl, benzooxazolyl, benzo[d]thiazolyl, benzothiadiazolyl, benzo[b][1,4]dioxepinyl, benzo[b][1,4]oxazinyl, 1,4-benzodioxanyl, benzonaphthofuranyl, benzoxazolyl, benzodioxolyl, benzodioxinyl, benzoxazolyl, benzopyranyl, benzopyranonyl, benzofuranyl, benzofuranonyl, benzofurazanyl, benzothiazolyl, benzothienyl (benzothiophenyl), benzothieno[3,2-d]pyrimidinyl, benzotriazolyl, benzo[4,6]imidazo[1,2-a]pyridinyl, carbazolyl, cinnolinyl, cyclopenta[d]pyrimidinyl, 6,7-dihydro-5H-cyclopenta[4,5]thieno[2,3-d]pyrimidinyl, 5,6-dihydrobenzo[h]quinazolinyl, 5,6-dihydrobenzo[h]cinnolinyl, 6,7-dihydro-5H-benzo[6,7]cyclohepta[1,2-c]pyridazinyl, dibenzofuranyl, dibenzothiophenyl, furanyl, furazanyl, furanonyl, furo[3,2-c]pyridinyl, 5,6,7,8,9,10-hexahydrocycloocta[d]pyrimidinyl, 5,6,7,8,9,10-hexahydrocycloocta[d]pyridazinyl, 5,6,7,8,9,10-hexahydrocycloocta[d]pyridinyl, isothiazolyl, imidazolyl, indazolyl, indolyl, indazolyl, isoindolyl, indolinyl, isoindolinyl, isoquinolyl, indolizinyl, isoxazolyl, 5,8-methano-5,6,7,8-tetrahydroquinazolinyl, naphthyridinyl, 1,6-naphthyridinonyl, oxadiazolyl, 2-oxoazepinyl, oxazolyl, oxiranyl, 5,6,6a,7,8,9,10,10a-octahydrobenzo[h]quinazolinyl, 1-phenyl-1H-pyrrolyl, phenazinyl, phenothiazinyl, phenoxazinyl, phthalazinyl, pteridinyl, purinyl, pyranyl, pyrrolyl, pyrazolyl, pyrazolo[3,4-d]pyrimidinyl, pyridinyl, pyrido[3,2-d]pyrimidinyl, pyrido[3,4-d]pyrimidinyl, pyrazinyl, pyrimidinyl, pyridazinyl, pyrrolyl, quinazolinyl, quinoxalinyl, quinolinyl, isoquinolinyl, tetrahydroquinolinyl, 5,6,7,8-tetrahydroquinazolinyl, 5,6,7,8-tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidinyl, 6,7,8,9-tetrahydro-5H-cyclohepta[4,5]thieno[2,3-d]pyrimidinyl, 5,6,7,8-tetrahydropyrido[4,5-c]pyridazinyl, thiazolyl, thiadiazolyl, thiapyranyl, triazolyl, tetrazolyl, triazinyl, thieno[2,3-d]pyrimidinyl, thieno[3,2-d]pyrimidinyl, thieno[2,3-c]pridinyl, and thiophenyl (i.e., thienyl). Unless stated otherwise in the specification, a heteroaryl moiety is optionally substituted by one or more substituents which independently include: acyl, alkyl, alkenyl, alkynyl, alkoxy, alkylaryl, cycloalkyl, aralkyl, aryl, aryloxy, amino, amido, amidino, imino, azide, carbonate, carbamate, carbonyl, heteroalkyl, heteroaryl, heteroarylalkyl, heterocycloalkyl, hydroxy, cyano, halo, haloalkoxy, haloalkyl, ester, ether, mercapto, thio, alkylthio, arylthio, thiocarbonyl, nitro, oxo, phosphate, phosphonate, phosphinate, silyl, sulfinyl, sulfonyl, sulfonamidyl, sulfoxyl, sulfonate, urea, —Si(R^a)₃—, —OR^a, —SR^a, —OC(O)—R^a, —N(R^a)₂, —C(O)R^a, —C(O)OR^a, —OC(O)N(R^a)₂, —C(O)N(R^a)₂, —N(R^a)C(O)OR^a, —N(R^a)C(O)R^a, —N(R^a)C(O)N(R^a)₂, N(R^a)C(NR^a)N(R^a)₂, —N(R^a)S(O)_tR^a (where t is 1 or 2), —S(O)_tOR^a (where t is 1 or 2), —S(O)_tN(R^a)₂ (where t is 1 or 2), or —O—P(═O)(OR^a)₂ where each R^a is independently hydrogen, alkyl, haloalkyl, carbocyclyl, carbocyclylalkyl, aryl, aralkyl, heterocycloalkyl, heterocycloalkylalkyl, heteroaryl or heteroarylalkyl and each of these moieties can be optionally substituted as defined herein.

The term “heteroaralkyl” refers to an alkyl group, as defined herein, substituted by a heteroaryl group, as defined herein, wherein the point of attachment is on the alkyl group.

“Heteroaryl-heterocycloalkyl” refers to an -(heteroaryl)heterocycloalkyl radical where heteroaryl and heterocycloalkyl are as disclosed herein and which are optionally substituted by one or more of the substituents described as suitable substituents for heteroaryl and heterocycloalkyl respectively. The “heteroaryl-heterocycloalkyl” is bonded to the parent molecular structure through an atom of the heteroaryl group.

“Heteroaryl-cycloalkyl” refers to an -(heteroaryl)cycloalkyl radical where heteroaryl and cycloalkyl are as disclosed herein and which are optionally substituted by one or more of the substituents described as suitable substituents for heteroaryl and cycloalkyl respectively. The “heteroaryl-cycloalkyl” is bonded to the parent molecular structure through a carbon atom of the heteroaryl group.

As used herein, the terms “heterocycloalkyl”, “heterocyclyl” or ‘heterocarbocyclyl” refer to any 3- to 18-membered non-aromatic radical monocyclic or polycyclic moiety comprising at least one heteroatom selected from nitrogen, oxygen, phosphorous and sulfur. A heterocyclyl group can be a monocyclic, bicyclic, tricyclic or tetracyclic ring system, wherein the polycyclic ring systems can be a fused, bridged or spiro ring system. Heterocyclyl polycyclic ring systems can include one or more heteroatoms in one or both rings. A heterocyclyl group can be saturated or partially unsaturated. Partially unsaturated heterocycloalkyl groups can be termed “heterocycloalkenyl” if the heterocyclyl contains at least one double bond, or “heterocycloalkynyl” if the heterocyclyl contains at least one triple bond. Whenever it appears herein, a numerical range such as “5 to 18” refers to each integer in the given range; e.g., “5 to 18 ring atoms” means that the heterocyclyl group can consist of 5 ring atoms, 6 ring atoms, etc., up to and including 18 ring atoms. For example, bivalent radicals derived from univalent heterocyclyl radicals whose names end in “-yl” by removal of one hydrogen atom from the atom with the free valence are named by adding “-idene” to the name of the corresponding univalent radical, e.g., a piperidine group with two points of attachment is a piperidylidene.

In some embodiments, these terms refer to a stable non-aromatic 5-7 membered monocyclic hydrocarbon or stable non-aromatic 7-10 membered bicyclic hydrocarbon that is either saturated or partially unsaturated, and having, in addition to carbon atoms, one or more heteroatoms. Heterocycloalkyl or heterocyclyl groups, unless otherwise specified, may optionally be substituted with one or more substituents. When used in reference to a ring atom of a heterocycloalkyl group, the term “nitrogen” includes a substituted nitrogen. The heteroatom(s) in the heterocyclyl radical can be optionally oxidized. One or more nitrogen atoms, if present, can be optionally quaternized. Heterocyclyl also includes ring systems substituted with one or more nitrogen oxide (—O—) substituents, such as piperidinyl N-oxides. The heterocyclyl is attached to the parent molecular structure through any atom of any of the ring(s). The point of attachment of a heterocycloalkyl group may be at any of its heteroatom or carbon ring atoms that results in a stable structure.

In some embodiments, a heterocyclyl group is a 3-10 membered non-aromatic ring system having ring carbon atoms and 1-4 ring heteroatoms, wherein each heteroatom is independently selected from nitrogen, oxygen, phosphorous and sulfur (“3-10 membered heterocyclyl”). In some embodiments, a heterocyclyl group is a 5-8 membered non-aromatic ring system having ring carbon atoms and 1-4 ring heteroatoms, wherein each heteroatom is independently selected from nitrogen, oxygen, phosphorous and sulfur (“5-8 membered heterocyclyl”). In some embodiments, a heterocyclyl group is a 5-6 membered non-aromatic ring system having ring carbon atoms and 1-4 ring heteroatoms, wherein each heteroatom is independently selected from nitrogen, oxygen, phosphorous and sulfur (“5-6 membered heterocyclyl”). In some embodiments, the 5-6 membered heterocyclyl has 1-3 ring heteroatoms selected from nitrogen, oxygen phosphorous and sulfur. In some embodiments, the 5-6 membered heterocyclyl has 1-2 ring heteroatoms selected from nitrogen, oxygen, phosphorous and sulfur. In some embodiments, the 5-6 membered heterocyclyl has 1 ring heteroatom selected from nitrogen, oxygen, phosphorous and sulfur.

Examples of heterocycloalkyl groups include, without limitation, tetrahydrofuranyl, tetrahydrothienyl, pyrrolidinyl, pyrrolidonyl, piperidinyl, pyrrolinyl, tetrahydroquinolinyl, tetrahydroisoquinolinyl, decahydroquinolinyl, oxazolidinyl, piperazinyl, dioxanyl, dioxolanyl, diazepinyl, oxazepinyl, thiazepinyl, morpholinyl, and quinuclidinyl. “Heterocycloalkyl” also include groups in which the heterocycloalkyl ring is fused to one or more aryl, heteroaryl or cycloalkyl rings, such as indolinyl, chromanyl, phenanthridinyl, or tetrahydroquinolinyl, where the radical or point of attachment is on the heterocycloalkyl ring.

Exemplary 3-membered heterocyclyls containing 1 heteroatom include, without limitation, azirdinyl, oxiranyl, thiorenyl. Exemplary 4-membered heterocyclyls containing 1 heteroatom include, without limitation, azetidinyl, oxetanyl and thietanyl. Exemplary 5-membered heterocyclyls containing 1 heteroatom include, without limitation, tetrahydrofuranyl, dihydrofuranyl, tetrahydrothiophenyl, dihydrothiophenyl, pyrrolidinyl, dihydropyrrolyl and pyrrolyl-2,5-dione. Exemplary 5-membered heterocyclyls containing 2 heteroatoms include, without limitation, dioxolanyl, oxathiolanyl and dithiolanyl. Exemplary 5-membered heterocyclyls containing 3 heteroatoms include, without limitation, triazolinyl, oxadiazolinyl, and thiadiazolinyl. Exemplary 6-membered heterocyclyl groups containing 1 heteroatom include, without limitation, piperidinyl, tetrahydropyranyl, dihydropyridinyl, and thianyl. Exemplary 6-membered heterocyclyl groups containing 2 heteroatoms include, without limitation, piperazinyl, morpholinyl, dithianyl, dioxanyl, and triazinanyl. Exemplary 7-membered heterocyclyl groups containing 1 heteroatom include, without limitation, azepanyl, oxepanyl and thiepanyl. Exemplary 8-membered heterocyclyl groups containing 1 heteroatom include, without limitation, azocanyl, oxecanyl and thiocanyl. Exemplary bicyclic heterocyclyl groups include, without limitation, indolinyl, isoindolinyl, dihydrobenzofuranyl, dihydrobenzothienyl, tetrahydrobenzothienyl, tetrahydrobenzofuranyl, tetrahydroindolyl, tetrahydroquinolinyl, tetrahydroisoquinolinyl, decahydroquinolinyl, decahydroisoquinolinyl, octahydrochromenyl, octahydroisochromenyl, decahydronaphthyridinyl, decahydro-1,8-naphthyridinyl, octahydropyrrolo[3,2-b]pyrrole, indolinyl, phthalimidyl, naphthalimidyl, chromanyl, chromenyl, 1H-benzo[e][1,4]diazepinyl, 1,4,5,7-tetrahydropyrano[3,4-b]pyrrolyl, 5,6-dihydro-4H-furo[3,2-b]pyrrolyl, 6,7-dihydro-5H-furo[3,2-b]pyranyl, 5,7-dihydro-4H-thieno[2,3-c]pyranyl, 2,3-dihydro-1H-pyrrolo[2,3-b]pyridinyl, 2,3-dihydrofuro[2,3-b]pyridinyl, 4,5,6,7-tetrahydro-1H-pyrrolo[2,3-b]pyridinyl, 4,5,6,7-tetrahydrofuro[3,2-c]pyridinyl, 4,5,6,7-tetrahydrothieno[3,2-b]pyridinyl, 1,2,3,4-tetrahydro-1,6-naphthyridinyl, and the like.

Unless stated otherwise, heterocyclyl moieties are optionally substituted by one or more substituents which independently include: acyl, alkyl, alkenyl, alkynyl, alkoxy, alkylaryl, cycloalkyl, aralkyl, aryl, aryloxy, amino, amido, amidino, imino, azide, carbonate, carbamate, carbonyl, heteroalkyl, heteroaryl, heteroarylalkyl, heterocycloalkyl, hydroxy, cyano, halo, haloalkoxy, haloalkyl, ester, ether, mercapto, thio, alkylthio, arylthio, thiocarbonyl, nitro, oxo, phosphate, phosphonate, phosphinate, silyl, sulfinyl, sulfonyl, sulfonamidyl, sulfoxyl, sulfonate, urea, —Si(R^a)_3-, —OR^a, —SR^a, —OC(O)—R^a, —N(R^a)₂, —C(O)R^a, —C(O)OR^a, —OC(O)N(R^a)₂, —C(O)N(R^a)₂, —N(R^a)C(O)OR^a, —N(R^a)C(O)R^a, —N(R^a)C(O)N(R^a)₂, N(R^a)C(NR^a)N(R^a)₂, —N(R^a)S(O)_tR^a (where t is 1 or 2), —S(O)_tOR^a (where t is 1 or 2), —S(O)_tN(R^a)₂ (where t is 1 or 2), or —O—P(═O)(OR^a)₂ where each R^a is independently hydrogen, alkyl, haloalkyl, carbocyclyl, carbocyclylalkyl, aryl, aralkyl, heterocycloalkyl, heterocycloalkylalkyl, heteroaryl or heteroarylalkyl and each of these moieties can be optionally substituted as defined herein.

“Heterocyclyl-alkyl” refers to a -(heterocyclyl)alkyl radical where heterocyclyl and alkyl are as disclosed herein and which are optionally substituted by one or more of the substituents described as suitable substituents for heterocyclyl and alkyl respectively. The “heterocyclyl-alkyl” is bonded to the parent molecular structure through any atom of the heterocyclyl group. The terms “heterocyclyl-alkenyl” and “heterocyclyl-alkynyl” mirror the above description of “heterocyclyl-alkyl” wherein the term “alkyl” is replaced with “alkenyl” or “alkynyl” respectively, and “alkenyl” or “alkynyl” are as described herein.

As used herein, the term “hydroxyl” or “hydroxy” refers to the group —OH.

As used herein, the term “imide” or “imido” refers to the group —C(═NR′)N(R′)₂ or —NR′C(═NR′)R′ wherein each R′ is, independently, hydrogen or a carbon moiety, such as, for example, an alkyl, alkenyl, alkynyl, aryl or heteroaryl group, as defined herein, or wherein two R′ groups together with the nitrogen atom to which they are bound form a 5-8 membered ring.

“Imino” refers to the “—(C═N)—R^b” radical where R^b is selected from hydrogen, alkyl, alkenyl, alkynyl, haloalkyl, heteroalkyl (bonded through a chain carbon), cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocycloalkyl (bonded through a ring carbon), heterocycloalkylalkyl, heteroaryl (bonded through a ring carbon) or heteroarylalkyl, unless stated otherwise in the specification, each of which moiety can itself be optionally substituted as described herein.

“Moiety” refers to a specific segment or functional group of a molecule. Chemical moieties are often recognized chemical entities embedded in or appended to a molecule.

“Nitro” refers to the —NO₂ radical.

“Oxa” refers to the —O— radical.

“Oxo” refers to the ═O radical.

“Phosphate” refers to a —O—P(═O)(OR^b)₂ radical, where each R^b is independently selected from hydrogen, alkyl, alkenyl, alkynyl, haloalkyl, heteroalkyl (bonded through a chain carbon), cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocycloalkyl (bonded through a ring carbon), heterocycloalkylalkyl, heteroaryl (bonded through a ring carbon) or heteroarylalkyl, unless stated otherwise in the specification, each of which moiety can itself be optionally substituted as described herein. In some embodiments, when R^a is hydrogen and depending on the pH, the hydrogen can be replaced by an appropriately charged counter ion.

“Phosphonate” refers to a —O—P(═O)(R^b)(OR^b) radical, where each R^b is independently selected from hydrogen, alkyl, alkenyl, alkynyl, haloalkyl, heteroalkyl (bonded through a chain carbon), cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocycloalkyl (bonded through a ring carbon), heterocycloalkylalkyl, heteroaryl (bonded through a ring carbon) or heteroarylalkyl, unless stated otherwise in the specification, each of which moiety can itself be optionally substituted as described herein. In some embodiments, when R^a is hydrogen and depending on the pH, the hydrogen can be replaced by an appropriately charged counter ion.

“Phosphinate” refers to a —P(═O)(R^b)(OR^b) radical, where each R^b is independently selected from hydrogen, alkyl, alkenyl, alkynyl, haloalkyl, heteroalkyl (bonded through a chain carbon), cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocycloalkyl (bonded through a ring carbon), heterocycloalkylalkyl, heteroaryl (bonded through a ring carbon) or heteroarylalkyl, unless stated otherwise in the specification, each of which moiety can itself be optionally substituted as described herein. In some embodiments, when R^a is hydrogen and depending on the pH, the hydrogen can be replaced by an appropriately charged counter ion.

“Silyl” refers to a —Si(R^b)₃ radical where each R^b is independently selected from alkyl, alkenyl, alkynyl, haloalkyl, heteroalkyl (bonded through a chain carbon), cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocycloalkyl (bonded through a ring carbon), heterocycloalkylalkyl, heteroaryl (bonded through a ring carbon) or heteroarylalkyl, unless stated otherwise in the specification, each of which moiety can itself be optionally substituted as described herein. In some embodiments, R^b is a carbon moiety, such as, for example, an alkyl, alkenyl, alkynyl, aryl or heteroaryl group.

“Sulfanyl”, “sulfide”, and “thio” each refer to the radical —S—R^b, wherein R^b is selected from alkyl, alkenyl, alkynyl, haloalkyl, heteroalkyl (bonded through a chain carbon), cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocycloalkyl (bonded through a ring carbon), heterocycloalkylalkyl, heteroaryl (bonded through a ring carbon) or heteroarylalkyl, unless stated otherwise in the specification, each of which moiety can itself be optionally substituted as described herein. For instance, an “alkylthio” refers to the “alkyl-S—” radical, and “arylthio” refers to the “aryl-S—” radical, each of which are bound to the parent molecular group through the S atom. The terms “sulfide”, “thiol”, “mercapto”, and “mercaptan” can also each refer to the group —R^bSH. As used herein, the term “alkthiooxy” refers to the group —SR′, wherein each R′ is, independently, a carbon moiety, such as, for example, an alkyl, alkenyl, or alkynyl group, as defined herein. As used herein, the term “arylthio” refers to the group —SR′, wherein each R′ is an aryl or heteroaryl group, as defined herein.

“Sulfinyl” or “sulfoxide” refers to the —S(O)—R^b radical, wherein for “sulfinyl”, R^b is H and for “sulfoxide”, R^b is selected from alkyl, alkenyl, alkynyl, haloalkyl, heteroalkyl (bonded through a chain carbon), cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocycloalkyl (bonded through a ring carbon), heterocycloalkylalkyl, heteroaryl (bonded through a ring carbon) or heteroarylalkyl, unless stated otherwise in the specification, each of which moiety can itself be optionally substituted as described herein.

“Sulfonyl” or “sulfone” refers to the —S(O₂)—R^b radical, wherein R^b is selected from hydrogen, alkyl, alkenyl, alkynyl, haloalkyl, heteroalkyl (bonded through a chain carbon), cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocycloalkyl (bonded through a ring carbon), heterocycloalkylalkyl, heteroaryl (bonded through a ring carbon) or heteroarylalkyl, unless stated otherwise in the specification, each of which moiety can itself be optionally substituted as described herein.

“Sulfonamidyl” or “sulfonamido” refers to the following radicals: —S(═O)₂—N(R^b)₂, —N(R^b)—S(═O)₂—R^b, —S(═O)₂—N(R^b)—, or —N(R^b)—S(═O)₂—, where each R^b is independently selected from hydrogen, alkyl, alkenyl, alkynyl, haloalkyl, heteroalkyl (bonded through a chain carbon), cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocycloalkyl (bonded through a ring carbon), heterocycloalkylalkyl, heteroaryl (bonded through a ring carbon) or heteroarylalkyl, unless stated otherwise in the specification, each of which moiety can itself be optionally substituted as described herein. The R^b groups in —S(═O)₂—N(R^b)₂ can be taken together with the nitrogen to which they are attached to form a 4-, 5-, 6-, or 7-membered heterocyclyl ring. In some embodiments, the term designates a C₁-C₄ sulfonamido, wherein each R^b in the sulfonamido contains 1 carbon, 2 carbons, 3 carbons, or 4 carbons total.

“Sulfoxyl” or “sulfoxide” refers to a —S(═O)2OH radical.

“Sulfonate” refers to a —S(═O)₂—OR^b radical, wherein R^b is selected from alkyl, alkenyl, alkynyl, haloalkyl, heteroalkyl (bonded through a chain carbon), cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocycloalkyl (bonded through a ring carbon), heterocycloalkylalkyl, heteroaryl (bonded through a ring carbon) or heteroarylalkyl, unless stated otherwise in the specification, each of which moiety can itself be optionally substituted as described herein.

“Thiocarbonyl” refers to a —(C═S)— radical.

“Urea” refers to a —N(R^b)—(C═O)—N(R^b)₂ or —N(R^b)—(C═O)—N(R^b)— radical, where each R^b is independently selected from alkyl, alkenyl, alkynyl, haloalkyl, heteroalkyl (bonded through a chain carbon), cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocycloalkyl (bonded through a ring carbon), heterocycloalkylalkyl, heteroaryl (bonded through a ring carbon) or heteroarylalkyl, unless stated otherwise in the specification, each of which moiety can itself be optionally substituted as described herein.

“Silyl” refers to a —Si(R^b)₃ radical where each R^b is independently selected from alkyl, alkenyl, alkynyl, haloalkyl, heteroalkyl (bonded through a chain carbon), cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocycloalkyl (bonded through a ring carbon), heterocycloalkylalkyl, heteroaryl (bonded through a ring carbon) or heteroarylalkyl, unless stated otherwise in the specification, each of which moiety can itself be optionally substituted as described herein.

“Sulfanyl”, “sulfide”, and “thio” each refer to the radical —S—R^b, wherein R^b is selected from alkyl, alkenyl, alkynyl, haloalkyl, heteroalkyl (bonded through a chain carbon), cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocycloalkyl (bonded through a ring carbon), heterocycloalkylalkyl, heteroaryl (bonded through a ring carbon) or heteroarylalkyl, unless stated otherwise in the specification, each of which moiety can itself be optionally substituted as described herein. For instance, an “alkylthio” refers to the “alkyl-S—” radical, and “arylthio” refers to the “aryl-S—” radical, each of which are bound to the parent molecular group through the S atom. The terms “sulfide”, “thiol”, “mercapto”, and “mercaptan” can also each refer to the group —R^bSH.

“Sulfinyl” or “sulfoxide” refers to the —S(O)—R^b radical, wherein for “sulfinyl”, R^b is H and for “sulfoxide”, R^b is selected from alkyl, alkenyl, alkynyl, haloalkyl, heteroalkyl (bonded through a chain carbon), cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocycloalkyl (bonded through a ring carbon), heterocycloalkylalkyl, heteroaryl (bonded through a ring carbon) or heteroarylalkyl, unless stated otherwise in the specification, each of which moiety can itself be optionally substituted as described herein.

“Sulfonyl” or “sulfone” refers to the —S(O₂)—R^b radical, wherein R^b is selected from hydrogen, alkyl, alkenyl, alkynyl, haloalkyl, heteroalkyl (bonded through a chain carbon), cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocycloalkyl (bonded through a ring carbon), heterocycloalkylalkyl, heteroaryl (bonded through a ring carbon) or heteroarylalkyl, unless stated otherwise in the specification, each of which moiety can itself be optionally substituted as described herein.

“Sulfonamidyl” or “sulfonamido” refers to the following radicals: —S(═O)₂—N(R^b)₂, —N(R^b)—S(═O)₂—R^b, —S(═O)₂—N(R^b)—, or —N(R^b)—S(═O)₂—, where each R^b is independently selected from hydrogen, alkyl, alkenyl, alkynyl, haloalkyl, heteroalkyl (bonded through a chain carbon), cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocycloalkyl (bonded through a ring carbon), heterocycloalkylalkyl, heteroaryl (bonded through a ring carbon) or heteroarylalkyl, unless stated otherwise in the specification, each of which moiety can itself be optionally substituted as described herein. The R^b groups in —S(═O)₂—N(R^b)₂ can be taken together with the nitrogen to which they are attached to form a 4-, 5-, 6-, or 7-membered heterocyclyl ring. In some embodiments, the term designates a C₁-C₄ sulfonamido, wherein each R^b in the sulfonamido contains 1 carbon, 2 carbons, 3 carbons, or 4 carbons total.

“Sulfoxyl” or “sulfoxide” refers to a —S(═O)₂OH radical.

“Sulfonate” refers to a —S(═O)₂—OR^b radical, wherein R^b is selected from alkyl, alkenyl, alkynyl, haloalkyl, heteroalkyl (bonded through a chain carbon), cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocycloalkyl (bonded through a ring carbon), heterocycloalkylalkyl, heteroaryl (bonded through a ring carbon) or heteroarylalkyl, unless stated otherwise in the specification, each of which moiety can itself be optionally substituted as described herein.

“Thiocarbonyl” refers to a —(C═S)— radical.

“Urea” refers to a —N(R^b)—(C═O)—N(R^b)₂ or —N(R^b)—(C═O)—N(R^b)— radical, where each R^b is independently selected from alkyl, alkenyl, alkynyl, haloalkyl, heteroalkyl (bonded through a chain carbon), cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocycloalkyl (bonded through a ring carbon), heterocycloalkylalkyl, heteroaryl (bonded through a ring carbon) or heteroarylalkyl, unless stated otherwise in the specification, each of which moiety can itself be optionally substituted as described herein.

Where substituent groups are specified by their conventional chemical formulae, written from left to right, they equally encompass the chemically identical substituents that would result from writing the structure from right to left, e.g., —CH₂O— is equivalent to —OCH₂—.

A “leaving group or atom” is any group or atom that will, under the reaction conditions, cleave from the starting material, thus promoting reaction at a specified site. Suitable non-limiting examples of such groups unless otherwise specified include halogen atoms, mesyloxy, p-nitrobenzensulphonyloxy, trifluoromethyloxy, and tosyloxy groups.

“Protecting group” has the meaning conventionally associated with it in organic synthesis, i.e., a group that selectively blocks one or more reactive sites in a multifunctional compound such that a chemical reaction can be carried out selectively on another unprotected reactive site and such that the group can readily be removed after the selective reaction is complete. A variety of protecting groups are disclosed, for example, in T. H. Greene and P. G. M. Wuts, Protective Groups in Organic Synthesis, Third Edition, John Wiley & Sons, New York (1999), incorporated herein by reference in its entirety. For example, a hydroxy protected form is where at least one of the hydroxy groups present in a compound is protected with a hydroxy protecting group. Likewise, amines and other reactive groups can similarly be protected.

The term “unsaturated”, as used herein, means that a moiety has one or more double or triple bonds.

As used herein, the term “partially unsaturated” refers to a ring moiety that includes at least one double or triple bond. The term “partially unsaturated” is intended to encompass rings having multiple sites of unsaturation, but is not intended to include aromatic groups, such as aryl or heteroaryl moieties, as defined herein.

The term “diradical” as used herein refers to an alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl, and heteroaralkyl groups, as described herein, wherein 2 hydrogen atoms are removed to form a divalent moiety. Diradicals are typically end with a suffix of “-ene”. For example, alkyl diradicals are referred to as alkylenes (for example:

and —(CR′₂)_x— wherein R′ is hydrogen or other substituent and x is 1, 2, 3, 4, 5 or 6); alkenyl diradicals are referred to as “alkenylenes”; alkynyl diradicals are referred to as “alkynylenes”; aryl and aralkyl diradicals are referred to as “arylenes” and “aralkylenes”, respectively (for example:

heteroaryl and heteroaralkyl diradicals are referred to as “heteroarylenes” and “heteroaralkylenes”, respectively (for example:

cycloalkyl diradicals are referred to as “cycloalkylenes”; heterocycloalkyl diradicals are referred to as “heterocycloalkylenes”; and the like.

As used herein, the terms “substituted” or “substitution” mean that at least one hydrogen present on a group atom (e.g., a carbon or nitrogen atom) is replaced with a permissible substituent, e.g., a substituent which upon substitution for the hydrogen results in a stable compound, e.g., a compound which does not spontaneously undergo transformation such as by rearrangement, cyclization, elimination, or other reaction. Unless otherwise indicated, a “substituted” group can have a substituent at one or more substitutable positions of the group, and when more than one position in any given structure is substituted, the substituent is either the same or different at each position. Substituents include one or more group(s) individually and independently selected from acyl, alkyl, alkenyl, alkynyl, alkoxy, alkylaryl, cycloalkyl, aralkyl, aryl, aryloxy, amino, amido, azide, carbonate, carbonyl, heteroalkyl, heteroaryl, heteroarylalkyl, heterocycloalkyl, hydroxy, cyano, halo, haloalkoxy, haloalkyl, ester, mercapto, thio, alkylthio, arylthio, thiocarbonyl, nitro, oxo, phosphate, phosphonate, phosphinate, silyl, sulfinyl, sulfonyl, sulfonamidyl, sulfoxyl, sulfonate, urea, —Si(R^a)₃, —OR^a, —SR^a, —OC(O)—R^a, —N(R^a)₂, —C(O)R^a, —C(O)OR^a, —OC(O)N(R^a)₂, —C(O)N(R^a)₂, —N(R^a)C(O)OR^a, —N(R^a)C(O)R^a, —N(R^a)C(O)N(R^a)₂, N(R^a)C(NR^a)N(R^a)₂, —N(R^a)S(O)_tR^a (where t is 1 or 2), —S(O)_tOR^a (where t is 1 or 2), —S(O)_tN(R^a)₂ (where t is 1 or 2), —O—P(═O)(OR^a)₂, where each R^a is independently hydrogen, alkyl, haloalkyl, carbocyclyl, carbocyclylalkyl, aryl, aralkyl, heterocycloalkyl, heterocycloalkylalkyl, heteroaryl or heteroarylalkyl and each of these moieties can be optionally substituted as defined herein. For example, a cycloalkyl substituent can have a halide substituted at one or more ring carbons, and the like. The protecting groups that can form the protective derivatives of the above substituents are known to those of skill in the art and can be found in references such as Greene and Wuts, above.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. In case of conflict, the present application, including any definitions herein, will control.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts the chemical synthesis of IPI-926 (V-a) from cis-decalone starting material (I-a) as described in Tremblay et al., “Discovery of a Potent and Orally Active Hedgehog Pathway Antagonist (IPI-926)” J. Med. Chem. (2009) 52:4400-4418. Step 1 of the depicted synthesis, the K-selectride reduction, provided the reduced product (S)-(II-a) in >96:4 β to α selectivity.

FIG. 2 depicts the ruthenium-catalyzed transfer-hydrogenation of (I-a). Transfer-hydrogenation of (I-a) using 1 mol % of the achiral ruthenium transfer-hydrogenation catalyst (iii-g) provided the reduced product (S)-(II-a) in >98.7:1.3 β:α selectivity.

DETAILED DESCRIPTION

For example, in one aspect, provided herein is a process for preparing a compound of formula (II):

or its pharmaceutically acceptable forms thereof;

from a compound of formula (I):

or its pharmaceutically acceptable forms thereof;

wherein:

R¹ is H, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl, heteroaralkyl, haloalkyl, —OR¹⁶, —C(O)R¹⁶, —CO₂R¹⁶, —SO₂R¹⁶, —C(O)N(R¹⁷)(R¹⁷), —[C(R¹⁶)₂]q-R¹⁶, —[(W)—N(R¹⁷)C(O)]_qR¹⁶, —[(W)—C(O)]_qR¹⁶, —[(W)—C(O)O]_qR¹⁶, —[(W)—OC(O)]_q, R¹⁶, —[(W)—SO₂]_qR¹⁶, —[(W)—N(R¹⁷)SO₂]_qR¹⁶, —[(W)—C(O)N(R¹⁷)]_qR¹⁷, —[(W)—O]_qR¹⁶, —[(W)—N(R¹⁷)]_qR¹⁶, or —[(W)—S]_qR¹⁶; wherein W is a diradical and q is 1, 2, 3, 4, 5, or 6;

each R² and R³ is, independently, H, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl, heteroaralkyl, haloalkyl, halo, —OR¹⁶, —OR¹⁶, —N(R¹⁷)₂, or —SR¹⁶, or R² and R³ taken together form a double bond or form a group:

wherein Z is NR¹⁷, O, or C(R¹⁸)₂;

R⁴ is independently H, halo, —OR¹⁶, —N(R¹⁷)₂, or —SR¹⁶;

each R⁵ and R⁶, is, independently, H, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl, heteroaralkyl, halo, —OR¹⁶, —N(R¹⁷)₂, or —SR¹⁶; or R⁵ and R⁶ taken together with the carbon to which they are bonded form C═O, C═S, C═N—OR¹⁷, C═N—R¹⁷, C═N—N(R¹⁷)₂, or form an optionally substituted 3-8 membered ring;

each R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹² and R¹³ is, independently, H, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl, heteroaralkyl, halo, —OR¹⁶, —N(R¹⁷)₂, or —SR¹⁶;

or R¹¹ and R¹² taken together, form a double bond;

or R¹⁰ and R¹¹ taken together, or R¹¹ and R¹² taken together, form a group:

wherein Z is NR¹⁷, O, or C(R¹⁸)₂;

each R¹⁴ and R¹⁵ is, independently, H, halo, —OR¹⁶, —N(R¹⁷)₂, or —SR¹⁶; or R¹⁴ and R¹⁵ taken together with the carbon to which they are bonded form C═O or C═S;

X is a bond or the group —C(R¹⁹)₂—, wherein each R¹⁹ is, independently, H, alkyl, aralkyl, halo, —CN, —OR¹⁶, or —N(R¹⁷)₂;

R¹⁶ is H, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl, heteroaralkyl or —[C(R²⁰)₂]_p—R²¹ wherein p is 0-6; or any two occurrences of R¹⁶ on the same substituent are taken together to form a 4-8 membered optionally substituted ring;

R¹⁷ is H, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl, heteroaralkyl, —C(═O)R²⁰, —C(═O)OR²⁰, —SO₂R²⁰, —C(═O)N(R²⁰)₂, or —[C(R²⁰)₂]_p—R²¹ wherein p is 0-6; or any two occurrences of R¹⁷ on the same substituent are taken together to form a 4-8 membered optionally substituted ring;

R¹⁸ is H, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl, heteroaralkyl, halo, —CN, —OR²⁰, —OSi(R²⁰)₃, —C(═O)R²⁰, —C(═O)OR²⁰, —SO₂R²⁰ or —C(═O)N(R²⁰)₂;

R²⁰ is H, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl, or heteroaralkyl; or any two occurrences of R²⁰ on the same substituent are taken together to form a 4-8 membered optionally substituted ring;

R²¹ is —OR²², —N(R²²)C(═O)R²², —N(R²²)C(═O)OR²², —N(R²²)SO₂(R²²), —C(═O)R²²N(R²²)₂, —OC(═O)R²²N(R²²(R²²), —SO₂N(R²²)(R²²), —N(R²²)(R²²), —C(═O)OR²², —C(═O)N(OH)(R²²), —OS(O)₂OR²², —S(O)₂OR²², —OP(═O)(OR²²)(OR²²), —N(R²²)P(O)(OR²²)(OR²²), or —P(═O)(OR²²)(OR²²); and

R²² is H, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl, heteroaralkyl; or any two occurrences of R²² on the same substituent are taken together to form a 4-8 membered optionally substituted ring;

the process comprising reacting a compound of formula (I) or its pharmaceutically acceptable forms thereof with a transfer-hydrogenation catalyst in order to provide a compound of formula (II) or its pharmaceutically acceptable forms thereof.

For example, in one aspect, provided herein is a process for preparing a compound of formula (II):

or its pharmaceutically acceptable forms thereof;from a compound of formula (I):

or its pharmaceutically acceptable forms thereof;wherein:

R¹ is alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl, heteroaralkyl, haloalkyl, heteroalkyl, —C(O)R¹⁶, —CO₂R¹⁶, —SO₂R¹⁶, —C(O)N(R¹⁷)(R¹⁷), —[C(R²³)₂]_q—R²³, —[(W)—N(R⁷)C(O)]R¹⁶, —[(W)—C(O)N(R¹⁷)]_qR¹⁷, —[(W)—N(R¹⁷)]_qR¹⁶, or —[(W)—S]_qR¹⁶; wherein W is (CH₂)_q and each q is independently 1, 2, 3, 4, 5, or 6;

each R² and R³ is, independently, H, alkyl, alkenyl, alkynyl, aralkyl, heteroaralkyl, haloalkyl, heteroalkyl, CN, NO₂, halo, —OR¹⁶, —N(R¹⁷)₂, or —SR¹⁶, or R² and R³ taken together form a double bond or form a group:

wherein Z is NR¹⁷, O, or C(R¹⁸)₂;

R⁴ is H, halo, —OR¹⁶, —N(R¹⁷)₂, or —SR¹⁶;

each R⁵ and R⁶, is, independently, H, alkyl, alkenyl, alkynyl, aralkyl, heteroaralkyl, heteroalkyl; or R⁵ and R⁶ taken together with the carbon to which they are bonded form C═O or C═S;

each R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹² and R¹³ is, independently, H, alkyl, alkenyl, alkynyl, aralkyl, heteroaralkyl, heteroalkyl, halo, or —OR¹⁶, or R¹¹ and R¹² taken together, form a double bond;

each R¹⁴ and R¹⁵ is, independently, H, alkyl, alkenyl, alkynyl, aralkyl, heteroaralkyl, heteroalkyl, halo, —OR¹⁶, —N(R¹⁷)₂, or —SR¹⁶; or R¹⁴ and R¹⁵ taken together with the carbon to which they are bonded form C═O or C═S;

X is a bond or the group —C(R¹⁹)₂—, wherein each R¹⁹ is, independently, H, alkyl, alkenyl, alkynyl, aralkyl, heteroaralkyl, heteroalkyl, halo, —CN, —NO₂, —OR¹⁶, or —N(R¹⁷)₂;

R¹⁶ is alkyl, alkenyl, alkynyl, alkoxy, arylalkoxy, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl, or heteroaralkyl; or any two occurrences of R¹⁶ on the same substituent are taken together to form a 4-8 membered optionally substituted ring;

R¹⁷ is H, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl, heteroaralkyl, —C(═O)R²⁰, —C(═O)OR²⁰, —SO₂R²⁰, or —C(═O)N(R²⁰)₂; or any two occurrences of R¹⁷ on the same substituent are taken together to form a 4-8 membered optionally substituted ring;

R¹⁸ is H, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl, heteroaralkyl, heteroalkyl, halo, —CN, —OR²⁰, —OSi(R²⁰)₃, —N(R¹⁷)₂, —C(═O)R²⁰, —C(═O)OR²⁰, —SO₂R²⁰ or —C(═O)N(R²⁰)₂;

R²⁰ is H, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl, or heteroaralkyl; or any two occurrences of R²⁰ on the same substituent are taken together to form a 4-8 membered optionally substituted ring; and

R²³ is H, alkyl, alkenyl, alkynyl, amido, or amino;

the process comprising reacting a compound of formula (I) or its pharmaceutically acceptable forms thereof with a transfer-hydrogenation catalyst in order to provide a compound of formula (II) or its pharmaceutically acceptable forms thereof.

For example, in one aspect, provided herein is a process for preparing a compound of formula (II):

or its pharmaceutically acceptable forms thereof;

from a compound of formula (I):

or its pharmaceutically acceptable forms thereof;

wherein:

R¹ is alkyl, alkenyl, alkynyl, aralkyl, —C(O)R¹⁶, —CO₂R⁶, —SO₂R¹⁶, —[C(R²³)₂]_q—R²³, —[(W)—N(R¹⁷)C(O)]_qR¹⁶, —[(W)—C(O)N(R¹⁷)]_qR¹⁷, or —[(W)—N(R¹⁷)]_qR¹⁶, W is (CH₂)_q and each q is independently 1, 2, 3, 4, 5, or 6;

R⁵ and R⁶ are each H, or R⁵ and R⁶ taken together with the carbon to which they are bonded form C═O;

R¹¹ and R¹² are each H, or R¹¹ and R¹² taken together form a double bond;

X is a bond or the group —CH₂—;

R¹⁶ is alkyl, alkenyl, alkynyl, aralkyl, alkoxy, arylalkoxy, or heteroaralkyl;

R¹⁷ is H, alkyl, alkenyl, or alkynyl; and

R²³ is H, alkyl, alkenyl, alkynyl, amido, or amino;

• • the process comprising reacting a compound of formula (I) or its pharmaceutically acceptable forms thereof with a transfer-hydrogenation catalyst in order to provide a compound of formula (II) or its pharmaceutically acceptable forms thereof.

In certain embodiments, R¹ is H, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl, heteroaralkyl, haloalkyl, —C(O)R¹⁶, —CO₂R⁶, —SO₂R¹⁶, —C(O)N(R¹⁷)(R¹⁷), or —[C(R⁶)₂]_q—R¹⁶. In certain embodiments, R¹ is H, aralkyl, —C(O)R¹⁶, —CO₂R¹⁶, —SO₂R¹⁶ or —C(O)N(R¹⁷)(R¹⁷). In certain embodiments, R¹ is H, aralkyl or —CO₂R¹⁶

In certain embodiments, R¹ is H.

In certain embodiments, R¹ is aralkyl (e.g., benzyl).

In certain embodiments, R¹ is —CO₂R¹⁶. In certain embodiments, R¹ is —CO₂R¹⁶ and R¹⁶ is alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl or heteroaralkyl. In certain embodiments, R¹ is a -Boc group (e.g., wherein R¹ is —CO₂R¹⁶ and R¹⁶ is t-butyl). In certain embodiments, R¹ is a -Cbz group (e.g., wherein R¹ is —CO₂R¹⁶ and R¹⁶ is benzyl).

In certain embodiments, R² and R³ are taken together form a double bond.

In certain embodiments, R² and R³ form a group:

wherein Z is —NR¹⁷—, —O—, or —C(R¹⁸)₂—. In certain embodiments, Z is —C(R¹⁸)₂—. In certain embodiments, Z is —CH₂—.

In certain embodiments, X is a bond. For example, in certain embodiments, wherein R² and R³ are taken together form a double bond, or wherein R² and R³ form a group:

and Z is —NR¹⁷—, —O—, or —C(R¹⁸)₂—, then X is a bond.

In certain embodiments, X is the group —C(R¹⁹)₂—. In certain embodiments, R¹⁹ is H, e.g., wherein X is —CH₂—.

In certain embodiments, wherein R² and R³ are taken together form a double bond, then X is the group —C(R¹⁹)₂—. In certain embodiments, wherein R² and R³ are taken together form a double bond, then X is the group —CH₂—.

In certain embodiments, R⁴ is H.

In certain embodiments, each R⁵ and R⁶, is, independently, H, or R⁵ and R⁶ taken together, along with the carbon to which they are bonded, form C═O. In certain embodiments, each of R⁵ and R⁶ is independently H. In certain embodiments, R⁵ and R⁶ taken together with the carbon to which they are bonded form C═O.

In certain embodiments, R⁷ and R⁸ are each H.

In certain embodiments, R⁹ and R¹⁰ are each H.

In certain embodiments, R¹ is a H.

In certain embodiments, R¹² and R¹³ are each H.

In certain embodiments, R¹⁴ and R¹⁵ are each H.

In certain embodiments, each of R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², R¹³, R¹⁴ and R¹⁵ is H.

In certain embodiments, R¹³ is H, and R¹¹ and R¹² taken together form a double bond.

In certain embodiments, the compound of formula (I) is a compound of the formula (I-AA):

or its pharmaceutically acceptable forms thereof,

and the compound of formula (II) is a compound of the formula (II-AA):

or its pharmaceutically acceptable forms thereof,

wherein R¹, R², R³, R⁵, R⁶, R¹⁰, R¹¹, R¹² and X are as defined herein.

In certain embodiments, the compound of formula (I) is a compound of the formula (I-AA):

or its pharmaceutically acceptable forms thereof,

and the compound of formula (II) is a compound of the formula (II-AA):

or its pharmaceutically acceptable forms thereof,

wherein X is —(CH₂)—;

R¹ is benzyl, or —CO₂R¹⁶ and R¹⁶ is benzyl;

R² and R³ are taken together to form a double bond;

R⁵ and R⁶ are each hydrogen or R⁵ and R⁶ taken together with the carbon to which they are bonded form C═O; and

R¹⁰, R¹¹ and R¹² are each hydrogen, or R¹¹ and R¹² taken together, form a double bond.

In certain embodiments, the compound of formula (I) is a compound of the formula (I-BB):

or its pharmaceutically acceptable forms thereof,

and the compound of formula (II) is a compound of the formula (II-BB):

or its pharmaceutically acceptable forms thereof,

wherein R¹, R², R³, R⁵, R⁶ and X are as defined herein.

In certain embodiments, the compound of formula (I) is a compound of the formula (I-CC):

or its pharmaceutically acceptable forms thereof,

and the compound of formula (II) is a compound of the formula (II-CC):

or its pharmaceutically acceptable forms thereof,

wherein R¹ and X are as defined herein.

Exemplary compounds of formula (I), and subgenera thereof, are provided in U.S. Pat. No. 7,812,164 and U.S. Publication No. 20090012109, each of which is incorporated herein by reference in their entirety.

In some embodiments, the compound of formula (I) or its pharmaceutically acceptable forms thereof include, but are not limited to the following:

or its pharmaceutically acceptable forms thereof.

Suitable compounds of Formula (I) for use in the processes disclosed herein can be accessed from members of the Liliaceae natural product family through synthetic methods within the knowledge scope of the skilled artisan. (See., e.g., Li, H.-J. et al., “Chemistry, bioactivity and geographical diversity of steroidal alkaloids from the Liliaceae family” Nat. Prod. Rep. (2006) 23:735-752, incorporated herein by reference in its entirety). Compounds of Formula (I) can result from the appropriate transformation of the following non-limiting examples of known Veratrum-type natural products, including jervine, jervinone, O-acetyljervine, methyljervine-N-3′-propanoate, 1-hydroxy-5,6-dihydrojervine, pseudojervine, verdine, verapatuline, cycloposine, hupehenisine, songbeisine, kuroyurinidine, 23-isokuroyurinidine, yibeissine, tortifolisine, peimicine, and ebeiensine.

In certain embodiments, the compound of formula (I) or its pharmaceutically acceptable forms thereof, and a compound of formula (II) or its pharmaceutically acceptable forms thereof, are selected from the set of compounds, or their pharmaceutically acceptable forms thereof, provided in Tables 1, 2, and 3, and wherein R¹ is as defined above and herein:

TABLE 1
Compound of formula (I) Compound of formula (II)

TABLE 2
Compound of formula (I) Compound of formula (II)

TABLE 3
Compound of formula (I) Compound of formula (II)

In certain embodiments, R¹ is H.

In certain embodiments, R¹ is aralkyl (e.g., benzyl).

In certain embodiments, R¹ is —CO₂R¹⁶. In certain embodiments, R¹ is —CO₂R¹⁶ and R¹⁶ is alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl or heteroaralkyl. In certain embodiments, R¹ is a -Boc group (e.g., wherein R¹ is —CO₂R¹⁶ and R¹⁶ is t-butyl). In certain embodiments, R¹ is a -Cbz group (e.g., wherein R¹ is —CO₂R¹⁶ and R¹⁶ is benzyl).

As used herein, the term “preferentially generates” refers to the production of one stereoisomer of a compound of formula (II) in excess over the other stereoisomer. In certain embodiments, the process preferentially generates a compound of formula (II), or its pharmaceutically acceptable forms thereof, wherein the carbon atom that is directly attached to the newly-formed hydroxyl group has the (R) or (S) configuration, in greater than 40% diastereomeric excess (de), greater than 50% de, greater than 60% de, greater than 70% de, greater than 75% de, greater than 80% de, greater than 85% de, greater than 90% de, greater than 95% de, greater than 98% de, or greater than 99% de, as determined by HPLC or other analytical methods known to the skilled artisan.

In certain embodiments, the process preferentially generates a compound of formula (II), or its pharmaceutically acceptable forms thereof, from a compound of formula (I), or its pharmaceutically acceptable forms thereof, wherein the carbon atom that is directly attached to the newly-formed hydroxyl group provided in formula (II) has the (R) or (S) configuration.

For example, in certain embodiments, the process preferentially generates a compound of formula (II), or its pharmaceutically acceptable forms thereof, from a compound of formula (I), or its pharmaceutically acceptable forms thereof, wherein the newly-formed hydroxyl group has the a (alpha) orientation; or the carbon atom that is directly attached to the newly-formed hydroxyl group has the (R) configuration; or the newly-formed hydroxyl group has the a (alpha) orientation, and the carbon atom that is directly attached to the newly-formed hydroxyl group has the (R) configuration; e.g., a compound of the formula (R)-(II):

or its pharmaceutically acceptable forms thereof,

wherein R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², R¹³, R¹⁴, R¹⁵ and X are as defined herein.

In certain embodiments, the process preferentially generates a compound of formula (II), or its pharmaceutically acceptable forms thereof, from a compound of formula (I), or its pharmaceutically acceptable forms thereof, wherein the newly-formed hydroxyl group has the β (beta) orientation; or the carbon atom that is directly attached to the newly-formed hydroxyl group has the (S) configuration; or the newly-formed hydroxyl group has the P (beta) orientation, and the carbon atom that is directly attached to the newly-formed hydroxyl group has the (S) configuration; e.g., a compound of the formula (S)-(II):

or its pharmaceutically acceptable forms thereof,

wherein R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², R¹³, R¹⁴, R¹⁵ and X are as defined herein.

In one embodiment, the process preferentially generates a compound of formula (II), or its pharmaceutically acceptable forms thereof, wherein the carbon atom that is directly attached to the newly-formed hydroxyl group has the (S) configuration.

In certain embodiments, the compound of formula (I) is a compound of the formula (I-AA):

or its pharmaceutically acceptable forms thereof,

and the compound of formula (II) is a compound of the formula (S)-(II-AA):

or its pharmaceutically acceptable forms thereof,

wherein R¹, R², R³, R⁵, R⁶, R¹⁰, R¹¹, R¹² and X are as defined herein.

In certain embodiments, the compound of formula (I) is a compound of the formula (I-BB):

or its pharmaceutically acceptable forms thereof,

and the compound of formula (II) is a compound of the formula (S)-(II-BB):

or its pharmaceutically acceptable forms thereof,

wherein R¹, R², R³, R⁵, R⁶ and X are as defined herein.

In certain embodiments, the compound of formula (I) is a compound of the formula (I-CC):

or its pharmaceutically acceptable forms thereof,

and the compound of formula (II) is a compound of the formula (II-CC):

or its pharmaceutically acceptable forms thereof,

wherein R¹ and X are as defined herein.

In another embodiment, the compounds of formulae (I) and (II) are selected from the set of compounds, or their pharmaceutically acceptable forms thereof, provided in Table 1.

In certain embodiments, the process preferentially generates a compound of formula (II) of Table 1, or its pharmaceutically acceptable forms thereof, wherein the carbon atom that is directly attached to the newly-formed hydroxyl group has the (S) configuration.

For example, in certain embodiments, the compounds of formulae (I) and (II) are selected from a set of compounds, or their pharmaceutically acceptable forms thereof, provided in Table 4, wherein the carbon atom that is directly attached to the newly-formed hydroxyl group of the compound of formula (II) has the (S) configuration:

TABLE 4
Compound of formula (I) Compound of formula (II)

In certain embodiments, the compound of formula (I) is a compound of formula (I-a)

or its pharmaceutically acceptable forms thereof,

and the compound of formula (II) is a compound of formula (S)-(II-a):

or its pharmaceutically acceptable forms thereof,

wherein R¹ is as defined herein, (see, e.g., FIG. 2).

In certain embodiments, R¹ is H.

In certain embodiments, R¹ is aralkyl (e.g., benzyl).

In certain embodiments, R¹ is —CO₂R¹⁶. In certain embodiments, R¹ is —CO₂R¹⁶ and R¹⁶ is alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocycloalkyl, aralkyl, heteroaryl or heteroaralkyl. In certain embodiments, R¹ is a -Boc group (e.g., wherein R¹ is —C₂R¹⁶ and R¹⁶ is t-butyl). In certain embodiments, R¹ is a -Cbz group (e.g., wherein R¹ is —CO₂R¹⁶ and R¹⁶ is benzyl).

Ruthenium Transfer—Hydrogenation Catalysts

As generally defined above, provided herein is a process of preparing a compound of formula (II), or its pharmaceutically acceptable forms thereof, from a compound of formula (I), or its pharmaceutically acceptable forms thereof, the process comprising reacting a compound of formula (I), or its pharmaceutically acceptable forms thereof, with a transfer-hydrogenation catalyst in order to provide a compound of formula (II), or its pharmaceutically acceptable forms thereof.

Exemplary transfer-hydrogenation catalysts include, for example, iridium transfer-hydrogenation catalysts, ruthenium transfer-hydrogenation catalysts and rhodium transfer-hydrogenation catalysts, e.g., as described in Zassinovich and Mestroni, Chem. Rev. (1992) 92:1051-1069, the entirety of which is incorporated herein by reference.

In certain embodiments, the transfer-hydrogenation catalyst is a ruthenium transfer-hydrogenation catalyst. Ruthenium transfer-hydrogenation catalysts are described in, for example, U.S. Pat. No. 6,184,381, U.S. Pat. No. 6,887,820, T. Ikariya et al., Org. Biomol. Chem. (2006) 4:393-406 and Hashiguchi et al., J. Am. Chem. Soc. (1995) 117:7562-7563 (“Noyori” ruthenium catalysts); U.S. Pat. No. 6,909,003; U.S. Pat. No. 6,545,188; U.S. Pat. No. 7,250,526; U.S. Pat. No. 6,372,931; U.S. Pat. No. 6,509,467; U.S. Pat. No. 7,112,690; U.S. Patent Application No. 2002/0193347 and Evaraere et al., Adv. Synth. Catal. (2003) 345:67-77 (“Carpentier” ruthenium catalysts); PCT application No. WO 2000/18708; PCT application No. WO 2001/09077; Reetz et al., J. Am. Chem. Soc. (2006) 1044-1045; Genov et al., Angew. Chem. (2004) 43:2816-2819; Sasson and Blum, Tet. Lett. (1971) 24:2167; Mao et al., Tet. Lett (2005) 46:7341-7344; H.-U. Blaser and H.-J. Federsel, Eds., Asymmetric Catalysis on Industrial Scale, 2^nd edition, (2010) Wiley-VCH: A. J. Blacker, P. Thompson, Scale up Studies in Asymmetric Transfer Hydrogenation, pgs. 265-289, the entirety of each of which is incorporated herein by reference. Such references describe the preparation and use of chiral ruthenium transfer-hydrogenation catalysts.

In certain embodiments, the ruthenium transfer-hydrogenation catalyst is a chiral ruthenium transfer-hydrogenation catalyst selected from Cl₃[((R)-tol-BINAP)RuCl]₂— Me₂NH₂⁺, Cl₃[((S)-tol-BINAP)RuCl]₂⁻ Me₂NH₂⁺, ((R)-DIFLUORPHOS)RuCl₂(DMF)_n, ((S)-DIFLUORPHOS)RuCl₂(DMF)_n, ((R)-DTBM-SEGPHOS)RuCl₂(p-cymene), ((S)-DTBM-SEGPHOS)RuCl₂(p-cymene), Cl₃[((R)-xylyl-SEGPHOS)RuCl]₂Me₂NH₂₊, Cl₃[((S)-xylyl-SEGPHOS)RuCl₂]⁻Me₂NH₂⁺, ((R)-xylyl-SEGPHOS)RuCl₂(R,R)DPEN, ((S)-xylyl-SEGPHOS)RuCl₂(S,S)DPEN, (Ph₃P)RuCl₂((+)-(R)—Fe-oxazoline), (Ph₃P)RuCl₂((−)-(S)—Fe-oxazoline), ((S,R)JOSIPHOS)RuCl₂(DMF)_n, ((R,S)JOSIPHOS)RuCl₂(DMF)_n, (11bS,11′bS)-4,4′-(9,9-Dimethyl-9H-xanthene-4,5-diyl)bis-dinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepine and its enantiomer, (S,S)TsDPEN-RuCl(p-cymene), (S,S)TsDPEN-RuCl(hexamethylbenzene), (S,S)TsCyDN-RuCl(hexamethylbenzene), RuHCl(mesitylene)[(1S,2R)-ephedrine], RuHCl(hexamethylbenzene)[(1S,2R)-ephedrine], RuHCl(hexamethylbenzene)[(1R,2S)-ephedrine], RuHCl(p-cymene)[(1S,2R)-ephedrine], RuHCl(p-cymene)[(1R,2S)-ephedrine], RuHCl(benzene)[(1S,2R)-ephedrine], RuHCl(mesitylene)[(1R,2S)₂-methylaminocyclohexanol], RuHCl(hexamethylbenzene) [(1R,2S)₂-methylaminocyclohexanol], RuHCl(hexamethylbenzene)[(1S,2S)₂-methylaminocyclohexanol], RuHCl(p-cymene)[(1R,2S)₂-methylaminocyclohexanol], and RuHCl(benzene)[(1R,2S)₂-methylaminocyclohexanol], RuHCl(hexamethylbenzene) [R-propranolol], RuHCl(hexamethylbenzene) [S-propranolol], RuHCl(hexamethylbenzene)[1R,2S-cis-1-amino-2-indanol], and RuHCl(hexamethylbenzene)[D-prolinol].

These ruthenium transfer-hydrogenation catalysts and others, both chiral and achiral, are further described below and herein.

Ligands Coordinated to the Catalyst

In certain embodiments, the ruthenium transfer-hydrogenation catalyst comprises one or more ligands.

Ligands can be classified as anionic (e.g., monoanionic, dianionic) or charge-neutral (see Green, “A new approach to the formal classification of covalent compounds of the elements” Journal of Organometallic Chemistry (1995) 500:127-148, incorporated herein by reference in its entirety). Ligands can also be classified according to the “denticity”, i.e., to the number of times a ligand bonds to a metal through non-contiguous donor sites (represented by “κⁿ” wherein “n” indicates the number of sites by which a ligand attaches to a metal). For example, a “monodentate” ligand (κ¹ ligand) refers to a ligand which bonds through one donor site, and a “bidentate” ligand (κ² ligand) refers to a ligand which bonds through two non-contiguous donor sites. Ligands can further be classified according to the “hapticity” of the ligand, i.e., the number of contiguous atoms that comprise a donor site and attach to the metal center (represented by “η^x” wherein “x” indicates the number of contiguous atoms). For example, an aromatic 6-membered ring (e.g., a benzene ring) can exist as an η² ligand, η⁴ ligand or η⁶ ligand depending upon the number of pi (π) electrons used in forming the coordinate bond.

Exemplary monoanionic monodentate ligands include, but are not limited to, iodo (I), bromo (Br⁻), chloro (Cl⁻), fluoro (F⁻), hydroxyl (HO⁻), cyano (CN⁻), nitro (NO₂⁻), isothiocyanato (SCN⁻) and S-thiocyanato (NCS⁻). In some embodiments, the monoanionic monodentate ligand is chloro (Cl⁻).

Exemplary monodentate neutral ligands include, but are not limited to, water (H₂O), acetonitrile (CH₃CN), ammonia (NH₃), carbon monoxide (CO), trimethylphosphine (PMe₃), tricyclohexylphosphine (PCy₃), triphenylphosphine (PPh₃), tri(o-tolyl)phosphine (P(o-tolyl)₃) and pyridine (C₅H₅N). In some embodiments, the monodentate neutral ligand is selected from trimethylphosphine (PMe₃), tricyclohexylphosphine (PCy₃), and triphenylphosphine (PPh₃).

Exemplary bidentate neutral ligands include, but are not limited to, 2,2′bipyridine, 1,10-phenanthroline, bisphosphino ligands (e.g., 1,2-bis(diphenylphophino)ethane, 1,2-bis(diphenylphophino)methane), diamine ligands (e.g., ethylenediamine) and amino alcohol ligands.

Exemplary η^x neutral ligands include, but are not limited to, optionally substituted benzene ligands, e.g., benzene (C₆H₆), toluene (C₆H₅CH₃), xylene (e.g., o-xylene, m-xylene, p-xyelene), cymene (e.g., o-cymene, m-cymene, p-cymene), mesitylene and hexamethylbenzene. In some embodiments, the η^x neutral ligand is selected from optionally substituted benzene (C₆H₆), p-cymene, mesitylene, and hexamethylbenzene.

In certain embodiments, the ruthenium transfer-hydrogenation catalyst comprises at least one ligand selected from an amino alcohol ligand, a monoanionic monodentate ligand and an optionally substituted benzene ligand. Such ligands will be further described below and herein.

Monodentate and Bidentate Neutral Ligands

In certain embodiments, the ruthenium transfer-hydrogenation catalyst comprises one or more monodentate or bidentate ligands. In some embodiments, these ligands can render chirality to the ruthenium transfer-hydrogenation catalyst. In other embodiments, these ligands generate an achiral ruthenium transfer-hydrogenation catalyst.

Exemplary monodentate phosphine ligands include, but are not limited to, trimethylphosphine (PMe₃), tricyclohexylphosphine (PCy₃), triphenylphosphine (PPh₃), tri(o-tolyl)phosphine (P(o-tolyl)₃), (S)—Fe-oxazoline, and (R)—Fe-oxazoline. Non-limiting examples of bidentate bisphosphino ligands include 1,2-bis(diphenylphophino)ethane, 1,2-bis(diphenylphophino)methane, (R)-tol-BINAP, (S)-tol-BINAP, (R)-DIFLUORPHOS), (S)-DIFLUORPHOS, (R)-DTBM-SEGPHOS, (S)-DTBM-SEGPHOS, (S,R)JOSIPHOS), (R,S)JOSIPHOS), 4,4′-(9,9-dimethyl-9H-xanthene-4,5-diyl)didinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepine, and (1 bS,11′bS)-4,4′-(9,9-Dimethyl-9H-xanthene-4,5-diyl)bis-dinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepine and its enantiomer.

In addition to the monodentate neutral ligand NH₃, other such monodentate amino ligands include, but are not limited to, unsubstituted or substituted alkyl, perhaloalkyl, alkenyl, alkynyl, cycloalkyl, aryl, or aralkyl amines. Exemplary alkyl amines include, but are not limited to, methyl, ethyl, isopropyl, n-propyl, n-butyl, sec-butyl, t-butyl, n-pentyl, isopentyl, and n-hexyl amine, or substituted variants thereof. Unsubstituted or substituted cycloalkyl amines include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl amines. Unsubstituted or substituted aryl amines and heteroaromatics include, but are not limited to, aniline, pyridine, pyrimidine.

Exemplary bidentate amino ligands include, but are not limited to, unsubstituted or substituted 2,2′bipyridine, ethylenediamine, propylenediamine, o-cyclopentyldiamine, o-cyclohexyldiamine, (R,R)-TsDPEN, (R,S)-TsDPEN, (S,R)-TsDPEN, (S,S)-TsDPEN, (R,R)-MsDPEN, (R,S)-MsDPEN, (S,R)-MsDPEN, and (S,S)-MsDPEN.

Exemplary methods for preparing ruthenium transfer-hydrogenation catalysts employing these phosphino and amino neutral ligands can be found, e.g., in the references detailed above.

Amino Alcohol Ligands

In certain embodiments, the ruthenium transfer-hydrogenation catalyst comprises an amino alcohol ligand.

In certain embodiments, the amino alcohol ligand is of the formula (i-a):

or its pharmaceutically acceptable forms thereof,

wherein each R^a and R^b are independently selected from hydrogen, alkyl, perhaloalkyl, alkenyl, alkynyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, aralkyl, and heteroaralkyl, or R^a and R^b are joined to form a 3-8 membered carbocyclic or heterocyclic ring system;

and R^c is selected from alkyl, perhaloalkyl, alkenyl, alkynyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, aralkyl, and heteroaralkyl.

In certain embodiments, the ruthenium transfer-hydrogenation catalyst is an achiral ruthenium transfer-hydrogenation catalyst.

In certain embodiments, the ruthenium transfer-hydrogenation catalyst is an achiral ruthenium transfer-hydrogenation catalyst comprising an amino alcohol ligand of the formula (i-a) where R^a and R^b are the same group. For example, in certain embodiments, R^a and R^b are the same group selected from C_1-6 alkyl and C_1-6 perhaloalkyl. In certain embodiments, R^a and R^b are the same group selected from C_1-6 alkyl. In certain embodiments, R^a and R^b are both —CH₃.

In certain embodiments, the ruthenium transfer-hydrogenation catalyst is a chiral ruthenium transfer-hydrogenation catalyst.

In certain embodiments, the ruthenium transfer-hydrogenation catalyst is a chiral ruthenium transfer-hydrogenation catalyst comprising an amino alcohol ligand of the formula (i-a). For example, in certain embodiments, R^a is hydrogen and R^b is C_1-6 alkyl, or R^b is hydrogen and R^a is C_1-6 alkyl. In certain embodiments, R^a is hydrogen and R^b is C_1-6 alkyl, or R^b is hydrogen and R^a is C_1-6 alkyl.

In certain embodiments, R^a is selected from alkyl and perhaloalkyl. In certain embodiments, R^a is selected from C_1-6 alkyl (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, sec-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl) and C_1-6 perhaloalkyl (e.g., —CF₃, —CCl₃, —CBr₃, —CF₂CF₃, etc). In certain embodiments, R^a is C_1-6 alkyl (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, sec-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl). In certain embodiments, R^a is C_1-6 perhaloalkyl (e.g., —CF₃, —CCl₃, —CBr₃, —CF₂CF₃, etc). In certain embodiments, R′ is methyl (—CH₃) or perfluoromethyl (—CF₃). In certain embodiments, R^a is methyl (—CH₃). In certain embodiments, R^a is perfluoromethyl (—CF₃).

For example, in certain embodiments, wherein R^a is methyl, the amino alcohol ligand is of the formula (i-b):

wherein R^b and R^c are as defined above and herein.

In certain embodiments, R^b is selected from alkyl and perhaloalkyl. In certain embodiments, R^b is selected from C_1-6 alkyl (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, sec-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl) and C_1-6 perhaloalkyl (e.g., —CF₃, —CCl₃, —CBr₃, —CF₂CF₃, etc). In certain embodiments, R^b is selected from C_1-6 alkyl (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, sec-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl). In certain embodiments, R^b is selected from C_1-6 perhaloalkyl (e.g., —CF₃, —CCl₃, —CBr₃, —CF₂CF₃, etc). In certain embodiments, R^b is methyl (—CH₃) or perfluoromethyl (—CF₃). In certain embodiments, R^b is methyl (—CH₃). In certain embodiments, R^b is perfluoromethyl (—CF₃).

For example, in certain embodiments, wherein R^b is methyl, the amino alcohol ligand is of the formula (i-c):

wherein R^a and R^c are as defined above and herein.

In certain embodiments, R^c is alkyl. In certain embodiments, R^c is C_1-6 alkyl (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, sec-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl). In certain embodiments, R^c is C_1-3 alkyl (e.g., methyl, ethyl, isopropyl, n-propyl). In certain embodiments, R^c is ethyl (—CH₂CH₃).

For example, in certain embodiments, wherein R^c is ethyl, the amino alcohol ligand is of the formula (i-d):

wherein R^a and R^b are as defined above and herein.

In certain embodiments, wherein R^a is methyl and R^c is ethyl, the amino alcohol ligand is of the formula (i-e):

wherein R^b is as defined above and herein.

In certain embodiments, wherein R^b is methyl and R^c is ethyl, the amino alcohol ligand is of the formula (i-f):

wherein R^a is as defined above and herein.

In certain embodiments, the amino alcohol of formula (i-a) is a chiral amino alcohol, which contains at least one asymmetric center). For example, in certain embodiments, R^a and R^b are different groups or at least one of R^a, R^b or R^c contains at least one asymmetric center. In certain embodiments, wherein the amino alcohol of formula (i-a) is a chiral amino alcohol, the ruthenium transfer-hydrogenation catalyst is also a chiral ruthenium transfer-hydrogenation catalyst.

In certain embodiments, wherein the amino alcohol of formula (i-a) is a chiral amino alcohol, R^a and R^b are different groups. For example, in certain embodiments, R^a is hydrogen and R^b is alkyl, perhaloalkyl, alkenyl, alkynyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, aralkyl, or heteroaralkyl. In certain embodiments, R^a is hydrogen and R^b is C_1-6 alkyl (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, sec-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl) or C_1-6 perhaloalkyl (e.g., —CF₃, —CCl₃, —CBr₃, —CF₂CF₃, etc). In certain embodiments, R^a is hydrogen and R^b is C_1-6 alkyl. In certain embodiments, R^a is hydrogen and R^b is methyl (—CH₃).

For example, in certain embodiments, wherein R^a is hydrogen and R^b is methyl, the amino alcohol ligand is of the formula (i-g):

wherein R^c is as defined above and herein.

In other embodiments, wherein the amino alcohol of formula (i-a) is a chiral amino alcohol, R^b is hydrogen and R^a is alkyl, perhaloalkyl, alkenyl, alkynyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, aralkyl, or heteroaralkyl. In certain embodiments, R^b is hydrogen and R^a is C_1-6 alkyl (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, sec-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl) or C_1-6 perhaloalkyl (e.g., —CF₃, —CCl₃, —CBr₃, —CF₂CF₃, etc). In certain embodiments, R^b is hydrogen and R^a is C_1-6 alkyl. In certain embodiments, R^b is hydrogen and R^a is methyl (—CH₃).

For example, in certain embodiments, wherein R^a is methyl and R^b is hydrogen, the amino alcohol ligand is of the formula (i-h):

wherein R^c is as defined above and herein.

However, in certain embodiments, the amino alcohol of formula (i-a) is an achiral amino alcohol, which does not contain an asymmetric center). For example, in certain embodiments, both R^a and R^b are the same group selected from alkyl, perhaloalkyl, alkenyl, alkynyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, aralkyl, and heteroaralkyl, or R^a and R^b are joined to form a 3-8 membered carbocyclic or heterocyclic ring system provided that R^a and R^b or the joined ring do not contain an asymmetric center. In certain embodiments, wherein the amino alcohol of formula (i-a) is an achiral amino alcohol, the ruthenium transfer-hydrogenation catalyst is an achiral ruthenium transfer-hydrogenation catalyst.

In certain embodiments wherein the amino alcohol of formula (i-a) is an achiral amino alcohol, both R^a and R^b are the same group selected from alkyl, perhaloalkyl, alkenyl, alkynyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, aralkyl, and heteroaralkyl. In certain embodiments, both R^a and R^b are the same group selected from alkyl and perhaloalkyl. In certain embodiments, both R^a and R^b are the same group selected from C_1-6 alkyl (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, sec-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl) and C_1-6 perhaloalkyl (e.g., —CF₃, —CCl₃, —CBr₃, —CF₂CF₃, etc). In certain embodiments, both R^a and R^b are the same group selected from C_1-6 alkyl (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, sec-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl). In certain embodiments, both R^a and R^b are the same group selected from C_1-6 perhaloalkyl (e.g., —CF₃, —CCl₃, —CBr₃, —CF₂CF₃, etc). In certain embodiments, both R^a and R^b are the same group selected from methyl (—CH₃) and perfluoromethyl (—CF₃). In certain embodiments, both R^a and R^b are methyl (—CH₃). In certain embodiments, both R^a and R^b are perfluoromethyl (—CF₃).

For example, in certain embodiments, wherein both R^a and R^b are methyl, the amino alcohol ligand is of the formula (i-i):

wherein R^c is as defined above and herein.

In some embodiments, R^c is hydrogen. In some embodiments, R^c is C_1-6alkyl (e.g., methyl, ethyl, propyl, isopropyl, butyl, isobutyl). In some embodiments, R^c is methyl. In some embodiments, R^c is ethyl. In some embodiments, R^c is propyl. In some embodiments, R^c is isopropyl.

For example, in certain embodiments, the amino alcohol is of the formula (i-j):

In certain embodiments wherein the amino alcohol of formula (i-a) is an achiral amino alcohol, R^a and R^b are joined to form a 3-8 membered carbocyclic or heterocyclic ring system provided that the joined ring does not contain an asymmetric center.

For example, in certain embodiments, R^a and R^b are joined to form a 3-, 4-, 5-, 6-, 7-, or 8-membered carbocyclic ring system provided that the joined ring does not contain an asymmetric center. In certain embodiments, R^a and R^b are joined to form a 3-, 4-, 5-, 6-, 7-, or 8-membered carbocyclic ring system selected from:

wherein R^c is as defined above and herein.

In certain embodiments, R^a and R^b are joined to form a 4-, 6- or 8-membered heterocyclic ring system provided that the joined ring does not contain an asymmetric center. In certain embodiments, R^a and R^b are joined to form a 4-, 6- or 8-membered heterocyclic ring system selected from:

wherein R^c is as defined above and herein,

R^e is a group selected from H, alkyl, perhaloalkyl, alkenyl, alkynyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, aralkyl, and heteroaralkyl, and

both R^f and R^g are the same group selected from alkyl, perhaloalkyl, alkenyl, alkynyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, aralkyl, or heteroaralkyl,

provided that the groups R^e, R^f and R^g do not contain an asymmetric center.

In some embodiments, R^a and R^b are joined to form a 4-, 6- or 8-membered heterocyclic ring system where the joined ring does contain an asymmetric center. In certain embodiments, R^a and R^b are joined to form a 4-, 6- or 8-membered heterocyclic ring system selected from:

wherein R^c is as defined above and herein, and

R^e is a group selected from H, alkyl, perhaloalkyl, alkenyl, alkynyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, aralkyl, and heteroaralkyl.

In certain embodiments, both R^f and R^g are the same group selected from alkyl and perhaloalkyl. In certain embodiments, both R^f and R^g are the same group selected from C_1-6 alkyl (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, sec-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl) and C_1-6 perhaloalkyl (e.g., —CF₃, —CCl₃, —CBr₃, —CF₂CF₃, etc). In certain embodiments, both R^f and R^g are the same group selected from C_1-6 alkyl (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, sec-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl). In certain embodiments, both R^f and R^g are the same group selected from C_1-6 perhaloalkyl (e.g., —CF₃, —CCl₃, —CBr₃, —CF₂CF₃, etc). In certain embodiments, both R^f and R^g are the same group selected from methyl (—CH₃) and perfluoromethyl (—CF₃). In certain embodiments, both R^f and R^g are methyl (—CH₃). In certain embodiments, both R^f and R^g are perfluoromethyl (—CF₃).

In some embodiments, the amino alcohol ligand is of Formula (i-z):

or its pharmaceutically acceptable forms thereof,

wherein each R^a and R^b are independently selected from hydrogen, alkyl, perhaloalkyl, aryloxyalkyl, alkenyl, alkynyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, aralkyl, and heteroaralkyl, or R^a and R^b are joined to form a 3-10 membered carbocyclic or heterocyclic ring system;

each Rⁿ and R^o are independently selected from hydrogen, alkyl, aryloxyalkyl, perhaloalkyl, alkenyl, alkynyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, aralkyl, and heteroaralkyl, or Rⁿ and R^o are joined to form a 3-10 membered carbocyclic or heterocyclic ring system; or

R^a and Rⁿ are joined together to form a 3-10 membered carbocyclic or heterocyclic ring system and R^b and R^o are each hydrogen; or

R^a and R^o are joined together to form a 3-10 membered carbocyclic or heterocyclic ring system and R^b and Rⁿ are each hydrogen; or

R^b and R^o are joined together to form a 3-10 membered carbocyclic or heterocyclic ring system and R^a and Rⁿ are each hydrogen; or

R^b and Rⁿ are joined together to form a 3-10 membered carbocyclic or heterocyclic ring system and R^a and R^o are each hydrogen; and

R^c i selected from alkyl, perhaloalkyl, alkenyl, alkynyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, aralkyl, and heteroaralkyl; or

R^a and R^c are joined together to form a 3-10 membered carbocyclic or heterocyclic ring system and R^b is hydrogen; or

R^b and R^c are joined together to form a 3-10 membered carbocyclic or heterocyclic ring system and R^a is hydrogen.

In certain embodiments, the ruthenium transfer-hydrogenation catalyst is a chiral ruthenium transfer-hydrogenation catalyst comprising an amino alcohol ligand of the formula (i-z). For example, in certain embodiments, R^a is hydrogen and R^b is C_1-6 alkyl, or R^b is hydrogen and R^a is C_1-6 alkyl. In certain embodiments, R^a is hydrogen and R^b is Me, or R^b is hydrogen and R^a is Me. In certain embodiments, Rⁿ is aryl and R^o is hydrogen, or R^o is hydrogen and Rⁿ is aryl. In certain embodiments, Rⁿ is phenyl and R^o is hydrogen, or R^o is hydrogen and Rⁿ is phenyl.

In certain embodiments, R^a is selected from alkyl and perhaloalkyl. In certain embodiments, R^a is selected from C_1-6 alkyl (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, sec-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl) and C_1-6 perhaloalkyl (e.g., —CF₃, —CCl₃, —CBr₃, —CF₂CF₃, etc). In certain embodiments, R^a is C_1-6 alkyl (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, sec-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl). In certain embodiments, R^a is C_1-6 perhaloalkyl (e.g., —CF₃, —CCl₃, —CBr₃, —CF₂CF₃, etc). In certain embodiments, R^a is methyl (—CH₃) or perfluoromethyl (—CF₃). In certain embodiments, R^a is methyl (—CH₃). In certain embodiments, R^a is perfluoromethyl (—CF₃).

In certain embodiments, R^b is selected from alkyl and perhaloalkyl. In certain embodiments, R^b is selected from C_1-6 alkyl (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, sec-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl) and C_1-6 perhaloalkyl (e.g., —CF₃, —CCl₃, —CBr₃, —CF₂CF₃, etc). In certain embodiments, R^b is selected from C_1-6 alkyl (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, sec-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl). In certain embodiments, R^b is selected from C_1-6 perhaloalkyl (e.g., —CF₃, —CCl₃, —CBr₃, —CF₂CF₃, etc). In certain embodiments, R^b is methyl (—CH₃) or perfluoromethyl (—CF₃). In certain embodiments, R^b is methyl (—CH₃). In certain embodiments, R^b is perfluoromethyl (—CF₃).

In certain embodiments, Rⁿ is selected from alkyl and perhaloalkyl. In certain embodiments, Rⁿ is selected from C_1-6 alkyl (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, sec-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl) and C_1-6 perhaloalkyl (e.g., —CF₃, —CCl₃, —CBr₃, —CF₂CF₃, etc). In certain embodiments, Rⁿ is selected from C_1-6 alkyl (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, sec-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl). In certain embodiments, Rⁿ is selected from C_1-6 perhaloalkyl (e.g., —CF₃, —CCl₃, —CBr₃, —CF₂CF₃, etc). In certain embodiments, R^o is methyl (—CH₃) or perfluoromethyl (—CF₃). In certain embodiments, Rⁿ is methyl (—CH₃). In certain embodiments, Rⁿ is perfluoromethyl (—CF₃).

In certain embodiments, R^o is selected from alkyl and perhaloalkyl. In certain embodiments, R^o is selected from C_1-6 alkyl (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, sec-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl) and C_1-6 perhaloalkyl (e.g., —CF₃, —CCl₃, —CBr₃, —CF₂CF₃, etc). In certain embodiments, R^o is selected from C_1-6 alkyl (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, sec-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl). In certain embodiments, R^o is selected from C_1-6 perhaloalkyl (e.g., —CF₃, —CCl₃, —CBr₃, —CF₂CF₃, etc). In certain embodiments, R^o is methyl (—CH₃) or perfluoromethyl (—CF₃). In certain embodiments, R^o is methyl (—CH₃). In certain embodiments, R^o is perfluoromethyl (—CF₃).

In certain embodiments, R^a is hydrogen and R^b is C_1-6 alkyl or R^b is hydrogen and R^a is C_1-6 alkyl, and Rⁿ and R^o are each hydrogen.

In certain embodiments, R^c is alkyl. In certain embodiments, R^c is C_1-6 alkyl (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, sec-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl). In certain embodiments, R^c is C_1-3 alkyl (e.g., methyl, ethyl, isopropyl, n-propyl). In certain embodiments, R^c is ethyl (—CH₂CH₃).

In certain embodiments, the amino alcohol of formula (i-z) is a chiral amino alcohol (i.e., the amino alcohol contains at least one asymmetric center). For example, in certain embodiments, R^a and R^b are different groups, Rⁿ and R^o are different groups, or at least one of R^a, R^b, Rⁿ, R^o or R^c contains at least one asymmetric center. In certain embodiments, wherein the amino alcohol of formula (i-z) is a chiral amino alcohol, the ruthenium transfer-hydrogenation catalyst is also a chiral ruthenium transfer-hydrogenation catalyst.

In certain embodiments, wherein the amino alcohol of formula (i-z) is a chiral amino alcohol, R^a and R^b are different groups. In certain embodiments, wherein the amino alcohol of formula (i-z) is a chiral amino alcohol, R^a and R^b are different groups. For example, in certain embodiments, R^a is hydrogen and R^b is alkyl, perhaloalkyl, alkenyl, alkynyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, aralkyl, or heteroaralkyl. In certain embodiments, R^a is hydrogen and R^b is C_1-6 alkyl (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, sec-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl) or C_1-6 perhaloalkyl (e.g., —CF₃, —CCl₃, —CBr₃, —CF₂CF₃, etc). In certain embodiments, R^a is hydrogen and R^b is C_1-6 alkyl. In certain embodiments, R^a is hydrogen and R^b is methyl (—CH₃).

In certain embodiments, R^b is hydrogen and R^a is alkyl, perhaloalkyl, alkenyl, alkynyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, aralkyl, or heteroaralkyl. In certain embodiments, R^b is hydrogen and R^a is C_1-6 alkyl (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, sec-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl) or C_1-6 perhaloalkyl (e.g., —CF₃, —CCl₃, —CBr₃, —CF₂CF₃, etc). In certain embodiments, R^b is hydrogen and R^a is C_1-6 alkyl. In certain embodiments, R^b is hydrogen and R^a is methyl (—CH₃).

In other embodiments, Rⁿ is hydrogen and R^o is alkyl, perhaloalkyl, alkenyl, alkynyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, aralkyl, or heteroaralkyl. In certain embodiments, R^o is hydrogen and Rⁿ is C_1-6 alkyl (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, sec-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl) or C_1-6 perhaloalkyl (e.g., —CF₃, —CCl₃, —CBr₃, —CF₂CF₃, etc). In certain embodiments, Rⁿ is hydrogen and R^o is C_1-6 alkyl. In certain embodiments, Rⁿ is hydrogen and R^o is methyl (—CH₃). In certain embodiments, R^o is hydrogen and Rⁿ is C_1-6alkyl. In certain embodiments, R^o is hydrogen and Rⁿ is methyl (—CH₃).

In certain embodiments, R^a, R^b and Rⁿ are each hydrogen, R^c is alkyl (e.g., isopropyl), and R^o is substituted alkyl, such as, but not limited to, aryloxyalkyl (e.g., naphthyloxymethyl). In other embodiments, R^a, R^b and R^o are each hydrogen, R^c is alkyl (e.g., isopropyl), and Rⁿ is substituted alkyl, such as, but not limited to, aryloxyalkyl (e.g., naphthyloxymethyl).

In some embodiments, the amino alcohol ligand of Formula (i-z) is (+)-(1S,2R)ephedrine, (−)-(1R,2S)ephedrine, (+)-(1S,2S)pseudoephedrine, or (−)-(1R,2R) pseudoephedrine. In some embodiments, the amino alcohol ligand is (+)-(1S,2R)ephedrine. In some embodiments, the amino alcohol ligand is (−)-(1R,2S)ephedrine.

In some embodiments, R^a and Rⁿ are joined together to form a 3-10 membered carbocyclic or heterocyclic ring system and R^b and R^o are each hydrogen. In some embodiments, R^a and R^o are joined together to form a 3-10 membered carbocyclic or heterocyclic ring system and R^b and Rⁿ are each hydrogen. In other embodiments, R^b and R^o are joined together to form a 3-10 membered carbocyclic or heterocyclic ring system and R^a and Rⁿ are each hydrogen. In certain embodiments, R^b and Rⁿ are joined together to form a 3-10 membered carbocyclic or heterocyclic ring system and R^a and R^o are each hydrogen. Exemplary 3-10 monocyclic carbocyclic ring systems include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclopentenyl, cyclohexyl, cyclohexenyl, cyclohexadienyl, cycloheptyl and cyclooctyl rings. Exemplary 3-10 bicyclic carbocyclic ring systems include bicyclo[2.2.1]heptanyl, bicyclo[2.2.2]octanyl, octahydro-1H-indenyl, decahydronaphthalenyl, and spiro[4.5]decanyl.

In one embodiment, R^a and R^o are joined together to form a cyclohexyl ring system, R^b and Rⁿ are each hydrogen, and R^c is C_1-6alkyl (e.g., Me). In another embodiment, R^b and Rⁿ are joined together to form a cyclohexyl ring system, R^a and R^o are each hydrogen, and R^c is C_1-6alkyl (e.g., Me). In another embodiment, R^a and Rⁿ are joined together to form a cyclohexyl ring system, R^b and R^o are each hydrogen, and R^o is C_1-6alkyl (e.g., Me). In another embodiment, R^b and R^o are joined together to form a cyclohexyl ring system, R^a and Rⁿ are each hydrogen, and R^c is C_1-6alkyl (e.g., Me). In another embodiment, R^a and Rⁿ are joined together to form a octahydro-1H-indenyl ring system, R^b and R^o are each hydrogen, and R^c is hydrogen. In another embodiment, R^b and R^o are joined together to form a octahydro-1H-indenyl ring system, R^a and Rⁿ are each hydrogen, and R^c is hydrogen. In some embodiments, R^a and R^e are joined together to form a 3-10 membered carbocyclic ring system (e.g., cyclopentyl) and R^b, Rⁿ and R^o are each hydrogen. In some embodiments, R^b and R^c are joined together to form a 3-10 membered carbocyclic ring system (e.g., cyclopentyl) and R^a, Rⁿ and R^o are each hydrogen.

Optionally Substituted Benzene Ligands

In certain embodiments, the ruthenium transfer-hydrogenation catalyst comprises an optionally substituted benzene ligand.

In certain embodiments, the optionally substituted benzene ligand is of the formula (ii-a):

wherein each R^h, Rⁱ, R^j, R^k, R^l, and R^m are independently selected from hydrogen, alkyl, perhaloalkyl, alkenyl, alkynyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, aralkyl, and heteroaralkyl.

In certain embodiments, each R^h, Rⁱ, R^j, R^k, R^l, and R^m are independently selected from hydrogen, alkyl and perhaloalkyl. In certain embodiments, each R^h, Rⁱ, R^j, R^k, R^l, and R^m are independently selected from hydrogen, C_1-6 alkyl (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, sec-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl) and C_1-6 perhaloalkyl (e.g., —CF₃, —CCl₃, —CBr₃, —CF₂CF₃, etc). In certain embodiments, each R^h, Rⁱ, R^j, R^k, R^l, and R^m are independently selected from hydrogen and C_1-6 alkyl (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, sec-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl). In certain embodiments, each R^h, Rⁱ, R^j, R^k, R^l, and R^m are independently selected from hydrogen and C_1-6 perhaloalkyl (e.g., —CF₃, —CCl₃, —CBr₃, —CF₂CF₃, etc). In certain embodiments, each R^h, Rⁱ, R^j, R^k, R^l, and R^m are independently selected from hydrogen, methyl (—CH₃) and perfluoromethyl (—CF₃). In certain embodiments, each R^h, Rⁱ, R^j, R^k, R^l, and R^m are independently selected from hydrogen and methyl (—CH₃). In certain embodiments, each R^h, Rⁱ, R^j, R^k, R^l, and R^m are independently selected from hydrogen and perfluoromethyl (—CF₃).

For example, in certain embodiments, wherein each R^h, Rⁱ, R^j, R^k, R^l, and R^m are independently selected from hydrogen and C_1-6 alkyl, the optionally substituted benzene ligand is selected from any one of the following ligands:

In some embodiments, the optionally substituted benzene ligand is selected from any one of the following ligands:

In certain embodiments, the hapticity of the optionally substituted benzene ligand is η². In certain embodiments, the hapticity of the optionally substituted benzene ligand is η⁴. In certain embodiments, the hapticity of the optionally substituted benzene ligand hapticity is η⁶.

In certain embodiments, the optionally substituted benzene ligand is η⁶-hexamethylbenzene.

Monoanionic Monodentate Ligands

In certain embodiments, the ruthenium transfer-hydrogenation catalyst includes a monoanionic monodentate ligand. Exemplary monoanionic monodentate ligands include, but are not limited to, halo (e.g., iodo (I⁻), bromo (Br⁻), chloro (Cl⁻) and fluoro (F⁻)), hydroxyl (HO⁻), cyano (CN⁻), nitro (NO₂⁻), isothiocyanato (SCN⁻) and S-thiocyanato (NCS⁻) ligands.

For example, in certain embodiments, the ruthenium transfer-hydrogenation catalyst comprises a halo ligand. In certain embodiments, the halo ligand is iodo (I⁻), bromo (Br⁻), or chloro (Cl⁻). In certain embodiments, the halo ligand is chloro (Cl⁻).

Ruthenium Transfer-Hydrogenation Catalyst

In certain embodiments, the ruthenium transfer-hydrogenation catalyst is a chiral ruthenium transfer-hydrogenation catalyst. In some embodiments, the ruthenium transfer-hydrogenation catalyst is selected from (S,S)TsDPEN-RuCl(p-cymene), ((S,R)JOSIPHOS)RuCl2(DMF)n, ((R,S)JOSIPHOS)RuCl2(DMF)n, (11bS,11′bS)-4,4′-(9,9-Dimethyl-9H-xanthene-4,5-diyl)bis-dinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepine and its enantiomer, RuHCl(mesitylene)[(1S,2R)-ephedrine], RuHCl(hexamethylbenzene)[(1S,2R)-ephedrine], RuHCl(hexamethylbenzene)[(1R,2S)-ephedrine], RuHCl(p-cymene)[(1R,2S)₂-methylaminocyclohexanol], RuHCl(hexamethylbenzene) [R-propranolol], RuHCl(hexamethylbenzene) [1R,2S-cis-1-amino-2-indanol], RuHCl(hexamethylbenzene) [(1R,2S)2-methylaminocyclohexanol], RuHCl(hexamethylbenzene) [(1S,2S)2-methylaminocyclohexanol], RuHCl(hexamethylbenzene)[R-propranolol], RuHCl(hexamethylbenzene)[S-propranolol], and (S,S)TsDPEN-RuCl(hexamethylbenzene).

In certain embodiments, the ruthenium transfer-hydrogenation catalyst is an achiral ruthenium transfer-hydrogenation catalyst.

In certain embodiments, the ruthenium transfer-hydrogenation catalyst is of the formula (iii-a):

wherein R^a, R^b, R^c, R^h, Rⁱ, R^j, R^k, R^l, and R^m are as defined above and herein.

In certain embodiments, the ruthenium transfer-hydrogenation catalyst is of the formula (iii-a):

wherein R^a and R^b are the same group selected from C_1-6 alkyl and C_1-6 perhaloalkyl, or R^a and R^b are joined to form a 3-8 membered carbocyclic or heterocyclic ring system;

R^c is selected from C_1-6 alkyl, C_1-6 perhaloalkyl, aralkyl, heteroaralkyl, aryl and heteroaryl; and

each R^h, Rⁱ, R^j, R^k, R^l, and R^m are independently selected from hydrogen, alkyl, perhaloalkyl, alkenyl, alkynyl, carbocycle, heterocycle, aryl, heteroaryl, aralkyl, or heteroaralkyl.

In certain embodiments, wherein R^a is methyl, the ruthenium transfer-hydrogenation catalyst is of the formula (iii-b):

wherein R^b, R^c, R^h, Rⁱ, R^j, R^k, R^l, and R^m are as defined above and herein

In certain embodiments, wherein R^b is methyl, the ruthenium transfer-hydrogenation catalyst is of the formula (iii-c):

wherein R^a, R^c, R^h, Rⁱ, R^j, R^k, R^l, and R^m are as defined above and herein.

In certain embodiments, wherein R^c is ethyl, the ruthenium transfer-hydrogenation catalyst is of the formula (iii-d):

wherein R^a, R^b, R^h, Rⁱ, R^j, R^k, R^l, and R^m are as defined above and herein.

In certain embodiments, wherein both R^a and R^b are methyl, the ruthenium transfer-hydrogenation catalyst is of the formula (iii-e):

wherein R^c, R^h, Rⁱ, R^j, R^k, R^l, and R^m are as defined above and herein.

In certain embodiments, wherein both R^a and R^b are methyl and R^c is ethyl, the ruthenium transfer-hydrogenation catalyst is of the formula (iii-f):

wherein R^h, Rⁱ, R^j, R^k, R^l, and R^m are as defined above and herein.

For example, in certain embodiments, the ruthenium transfer-hydrogenation catalyst is an achiral catalyst of the formula (iii-g):

In certain embodiments, the ruthenium transfer-hydrogenation catalyst is of the formula (iii-h):

wherein each R^a, R^b, Rⁿ and R^o are independently selected from hydrogen, alkyl, aryloxyalkyl, aryl, and perhaloalkyl, or

R^a and Rⁿ are joined together to form a 3-10 membered carbocyclic or heterocyclic ring system and R^b and R^o are each hydrogen; or

R^a and R^o are joined together to form a 3-10 membered carbocyclic or heterocyclic ring system and R^b and Rⁿ are each hydrogen; or

R^b and R^o are joined together to form a 3-10 membered carbocyclic or heterocyclic ring system and R^a and Rⁿ are each hydrogen; or

R^b and Rⁿ are joined together to form a 3-10 membered carbocyclic or heterocyclic ring system and R^a and R^o are each hydrogen; and

R^c is selected from C_1-6 alkyl, C_1-6 perhaloalkyl, aralkyl, heteroaralkyl, aryl and heteroaryl; and

each R^h, Rⁱ, R^j, R^k, R^l, and R^m are independently selected from hydrogen, alkyl, perhaloalkyl, alkenyl, alkynyl, carbocycle, heterocycle, aryl, heteroaryl, aralkyl, or heteroaralkyl.

In some embodiments, to form the ruthenium transfer hydrogenation catalyst, the Ru starting material is an (arene)Ru(X_a) dimer, such as (v-a):

wherein R^h, Rⁱ, R^j, R^k, R^l, and R^m are as defined above and herein, and

X^a is selected from halo (e.g., iodo (I⁻), bromo (Br⁻), chloro (Cl⁻) and fluoro (F⁻)).

In certain embodiments, X^a is selected from iodo (I⁻), bromo (Br⁻), and chloro (Cl⁻). In certain embodiments, X^a is chloro (Cl⁻). In some embodiments, each R^h, Rⁱ, R^j, R^k, R^l, and R^m are independently selected from hydrogen, alkyl, perhaloalkyl, alkenyl, alkynyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, aralkyl, and heteroaralkyl. In certain embodiments, each R^h, Rⁱ, R^j, R^k, R^l, and R^m are independently selected from hydrogen, C_1-6 alkyl (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, sec-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl) and C_1-6 perhaloalkyl (e.g., —CF₃, —CCl₃, —CBr₃, —CF₂CF₃, etc). In certain embodiments, each R^h, Rⁱ, R^j, R^k, R^l, and R^m are independently selected from hydrogen and methyl (—CH₃). In some embodiments, the optionally substituted arene ring is selected from benzene, toluene, o-xylene, m-xylene, p-xylene, mesitylene, hexamethylbenzene, o-cymene, m-cymene, and p-cymene. In some embodiments, the optionally substituted arene ring is selected from benzene, mesitylene, hexamethylbenzene, and p-cymene. In certain embodiments, the optionally substituted benzene ligand is η⁶-hexamethylbenzene.

The ruthenium transfer-hydrogenation catalyst can be prepared by a variety of known methods for complexation (see, e.g., T. Ikariya et al., Org. Biomol. Chem. (2006) 4:393-406). In some embodiments, the ruthenium transition metal catalyst is synthesized from an (arene)Ru(X_a)₂ dimer and an amino alcohol ligand in the presence of a base (e.g., an alkoxide base or an amine base) and alcoholic solvent (e.g., isopropanol). First, a catalyst precursor, such as (iii-i) or (iii-j), is formed having the monodentate anionic ligand X_a bound to Ru:

wherein R^a, R^b, R^c, R^h, Rⁱ, R^j, R^k, R^l, R^m, Rⁿ, R^o and X_a are as defined above and herein.

Upon addition of base, such as, but not limited to, an amine base (e.g., triethylamine) or an alkoxide base (e.g., KOiPr, NaOiPr, KOtBu, NaOtBu), the catalyst precursor can convert to the active hydrido catalyst (iii-a) or (iii-h) with concommitant formation of acetone:

wherein R^a, R^b, R^c, R^h, Rⁱ, R^j, R^k, R^l, R^m, Rⁿ, R^o and X_a are as defined above and herein.

During the transfer-hydrogenation reaction of a compound of formula (I) to form a compound of formula (II), in some embodiments, the active catalyst can cycle between the hydrido catalyst (iii-a) or (iii-h) and the free aminoalkoxy species (iii-k) or (iii-l), respectively:

wherein R^a, R^b, R^c, R^h, Rⁱ, R^j, R^k, R^l, R^m, Rⁿ, and R^o are as defined above and herein.

Thus, the term “ruthenium transfer-hydrogenation catalyst” as used herein refers to any and all ruthenium complexes of the formulas (iii-a), (iii-h), (iii-i), (iii-j), (iii-k), and (iii-l) and their mixtures, and all subgenuses thereof. In some embodiments, the ruthenium transfer-hydrogenation catalyst is a mixture of any or all of (iii-i), (iii-a), and (iii-k). In certain embodiments, the ruthenium transfer-hydrogenation catalyst is a mixture of any or all of (iii-j), (iii-h), and (iii-l).

In certain embodiments of formula (iii-i), R^a and R^b are the same group selected from C_1-6 alkyl and C_1-6 perhaloalkyl, or R^a and R^b are joined to form a 3-8 membered carbocyclic or heterocyclic ring system; R^c is selected from C_1-6 alkyl, C_1-6 perhaloalkyl, aralkyl, heteroaralkyl, aryl and heteroaryl; each R^h, Rⁱ, R^j, R^k, R^l, and R^m are independently selected from hydrogen, alkyl, perhaloalkyl, alkenyl, alkynyl, carbocycle, heterocycle, aryl, heteroaryl, aralkyl, or heteroaralkyl; and X^a is selected from halo (e.g., iodo (I⁻), bromo (Br⁻), chloro (Cl⁻) and fluoro (F⁻)). In certain embodiments of formula (iii-i), R^a and R^b are the same group selected from C_1-6 alkyl; R^c is selected from C_1-6 alkyl; each R^h, Rⁱ, R^j, R^k, R^l, and R^m are independently selected from hydrogen and C_1-6 alkyl; and X_a is Cl. In some embodiments of formula (iii-i), R^a and R^b are each Me, R^c is Et, each R^h, Rⁱ, R^j, R^k, R^l, and R^m is Me, and X_a is Cl.

In certain embodiments of formula (iii-k), R^a and R^b are the same group selected from C_1-6 alkyl and C_1-6 perhaloalkyl, or R^a and R^b are joined to form a 3-8 membered carbocyclic or heterocyclic ring system; R^c is selected from C_1-6 alkyl, C_1-6 perhaloalkyl, aralkyl, heteroaralkyl, aryl and heteroaryl; and each R^h, Rⁱ, R^j, R^k, R^l, and R^m are independently selected from hydrogen, alkyl, perhaloalkyl, alkenyl, alkynyl, carbocycle, heterocycle, aryl, heteroaryl, aralkyl, or heteroaralkyl. In certain embodiments of formula (iii-k), R^a and R^b are the same group selected from C_1-6 alkyl; R^c is selected from C_1-6 alkyl; and each R^h, Rⁱ, R^j, R^k, R^l, and R^m are independently selected from hydrogen and C_1-6 alkyl. In some embodiments of formula (iii-k), R^a and R^b are each Me, R^c is Et, and each R^h, Rⁱ, R^j, R^k, R^l, and R^m is Me.

Provided herein is an achiral catalyst comprising one or more complexes of formulas (iii-a) and (iii-k):

wherein, independently for each of formulas (iii-a) and (iii-k):

each R^a and R^b are the same group selected from hydrogen, alkyl, perhaloalkyl, alkenyl, alkynyl, carbocycle, heterocycle, aryl, heteroaryl, aralkyl, or heteroaralkyl, or R^a and R^b are joined to form a 3-8 membered carbocyclic or heterocyclic ring system;

R^c is selected from alkyl, perhaloalkyl, alkenyl, alkynyl, carbocycle, heterocycle, aryl, heteroaryl, aralkyl, or heteroaralkyl; and

each R^h, Rⁱ, R^j, R^k, R^l, and R^m are independently selected from hydrogen, alkyl, perhaloalkyl, alkenyl, alkynyl, carbocycle, heterocycle, aryl, heteroaryl, aralkyl, or heteroaralkyl.

In some embodiments, for both formulas (iii-a) and (iii-k), R^a and R^b are each Me, R^c is Et, and each R^h, Rⁱ, R^j, R^k, R^l, and R^m is Me.

Provided herein is an achiral catalyst of formula (iii-i):

wherein:

each R^a and R^b are the same group selected from hydrogen, alkyl, perhaloalkyl, alkenyl, alkynyl, carbocycle, heterocycle, aryl, heteroaryl, aralkyl, or heteroaralkyl, or R^a and R^b are joined to form a 3-8 membered carbocyclic or heterocyclic ring system;

R^c is selected from alkyl, perhaloalkyl, alkenyl, alkynyl, carbocycle, heterocycle, aryl, heteroaryl, aralkyl, or heteroaralkyl; and

each R^h, Rⁱ, R^j, R^k, R^l, and R^m are independently selected from hydrogen, alkyl, perhaloalkyl, alkenyl, alkynyl, carbocycle, heterocycle, aryl, heteroaryl, aralkyl, or heteroaralkyl; and

X_a is selected from iodo (I⁻), bromo (Br⁻), chloro (Cl⁻) and fluoro (F—).

In some embodiments, R^a and R^b are each Me, R^c is Et, each R^h, Rⁱ, R^j, R^k, R^l, and R^m is Me, and X_a is Cl⁻.

In certain embodiments, the ruthenium transfer-hydrogenation catalyst is generated by heating (hexamethylbenzene)RuCl₂ dimer and an amino alcohol in isopropanol and triethylamine. In other embodiments, the ruthenium transfer-hydrogenation catalyst is generated by heating (hexamethylbenzene)RuCl₂ dimer and an amino alcohol in isopropanol and an alkoxide base (e.g., KOiPr, NaOiPr, KOtBu, NaOtBu). In some embodiments, KOiPr is employed in the complexation reaction.

In certain embodiments, the ruthenium transfer-hydrogenation catalyst is generated from hexamethylbenzene ruthenium chloride dimer and an amino alcohol. In certain embodiments, the ruthenium transfer-hydrogenation catalyst is generated from hexamethylbenzene ruthenium chloride dimer and a chiral amino alcohol. In certain embodiments, the ruthenium transfer-hydrogenation catalyst is generated from hexamethylbenzene ruthenium chloride dimer and an achiral amino alcohol.

In certain embodiments, the ruthenium transition metal catalyst is prepared using about 0.1% to about 1 mol %, or about 0.25% to about 0.5% of a ruthenium halide dimer. In some embodiments, the ruthenium halide dimer is an (arene)ruthenium halide dimer, such as (hexamethylbenzene)RuCl₂ dimer. In some embodiments of the complexation reaction, the amino alcohol ligand is present in about 0.5 mol % to about 5 mol %, about 1 mol % to about 3 mol %, or about 1 mol % to about 2 mol %. In certain embodiments, the amino alcohol ligand is present in about 3 mol %. In some embodiments, the amino alcohol ligand is of Formula (i-a), such as (i-j). In certain embodiments, the amount of base used in the complexation reaction is about 0.25 mol % to about 10 mol %, about 0.5 mol % to about 5 mol %, or about 0.5 mol % to about 1 mol %. In some embodiments, the amount of base used in the complexation reaction is about 5 mol %. In some embodiments, the reaction is performed at about 25° C. to about 100° C., about 40° C. to about 80° C., or about 50° C. to 75° C. In certain embodiments, the reaction is performed at about 50° C. In other embodiments, the reaction is performed at about 80° C. In some embodiments, the reaction is performed for 1 hour or 2 hours.

Several exemplary non-limiting sets of reaction parameters for the synthesis of the ruthenium transition metal catalyst are given below in Table 5.

TABLE 5
		Amino		iPrOH
		Alcohol		(vol.
Parameter	(Hexamethylbenzene)	Ligand (i-j)	KOiPr	relative to	Temp	Time
Set	RuCl2 Dimer (mol %)	(mol %)	(mol %)	Ru dimer)	(° C.)	(h)
1	0.5	1.5	1.5	160	~80	2
2	0.5	2	1	100	~50	1
3	0.25	1	0.5	100	~50	1

Other Reaction Conditions

In one aspect, provided herein is a process for preparing a compound of formula (II) or its pharmaceutically acceptable forms thereof from a compound of formula (I) or its pharmaceutically acceptable forms thereof, the process comprising reacting a compound of formula (I) or its pharmaceutically acceptable forms thereof with a transfer-hydrogenation catalyst in order to provide a compound of formula (II) or its pharmaceutically acceptable forms thereof.

In certain embodiments, the process further comprises a base. Exemplary bases include, but are not limited to, alkoxides (e.g., KOiPr, NaOiPr, KOtBu, NaOtBu), hydroxides (e.g., KOH, NaOH) and tertiary amines (e.g., NEt₃). In certain embodiments, the base is an alkoxide. In certain embodiments, the base is KOiPr. In certain embodiments, the base is KOtBu. In other embodiments, the base is NaOiPr. In certain embodiments, the base is NaOtBu. In some embodiments, the base is NEt₃.

In certain embodiments, the process provides about 5 mol % to about 30 mol %, about 5 mol % to about 20 mol %, about 5 mol % to about 15 mol %, or about 5 mol % to about 10 mol % of base (calculated from the molar amount of compound (I)). In certain embodiments, the process provides about 10 mol % of base. In certain embodiments, the process provides about 20 mol % of base. In other embodiments, the process provides about 5% weight/volume of base. In some embodiments, the process provides about 0.1 to about 0.2 (e.g., 0.2) equivalents of base based upon the amount of compound (I).

In certain embodiments, the process further comprises a hydrogen donor. Exemplary hydrogen donors include, but are not limited to, organic alcohols (e.g., methanol (MeOH), ethanol (EtOH), isopropanol (iPrOH), t-butanol (tBuOH), benzyl alcohol) and formic acid or salts thereof (e.g., amonium formate, and alkyl ammonium formates such as triethylammoniumformate (TEAF)). In certain embodiments, the organic alcohol is isopropanol. In other embodiments, the organic alcohol is methanol. In some embodiments, the organic alcohol is t-butanol.

In some embodiments, the process comprises a mixture of a base (e.g., an alkoxide base as described herein) and a hydrogen donor (e.g., an organic alcohol as described herein). In certain embodiments, the ratio of base to hydrogen donor is 0.4 equivalents base/2 vol. hydrogen donor. In other embodiments, the ratio of base to hydrogen donor is 0.1 equivalents base/10 vol. hydrogen donor. In some embodiment, the base is KOiPr and the hydrogen donor is iPrOH.

In certain embodiments, the process further comprises a solvent. Exemplary solvents include, but are not limited to, ethers (e.g., dimethyl ether, diethyl ether, diisopropyl ether, methyltert-butyl ether, tetrahydrofuran (THF), 2-methyl tetrahydrofuran (2-Me-THF), 1,3-dioxolane, 1,4-dioxane), hydrocarbons (e.g., benzene, toluene, xylene, mesitylene, hexanes, heptanes, cyclohexane, methylcyclohexane, acetonitrile, acetone), polar aprotic solvents (e.g., dimethylformamide, dimethylsulfoxide), halogenated solvents (e.g., dichloromethane, chloroform) or combinations thereof. In certain embodiments, the solvent is an ether. In certain embodiments, the solvent is 2-methyl tetrahydrofuran (2-Me-THF). In some embodiments, the solvent is selected from acetonitrile, 2-methyl tetrahydrofuran (2-Me-THF), acetone, and mesitylene. In some embodiments, the solvent is mesitylene.

In certain embodiments, the process further comprises a hydrogen donor and a solvent, as described above and herein. For example, in certain embodiments, the process further comprises an organic alcohol and a solvent. In certain embodiments, the process further comprises a hydrogen donor and an ether solvent. In certain embodiments, the process further comprises isopropanol and 2-methyltetrahydrofuran. In certain embodiments, the process further comprises isopropanol and mesitylene. In some embodiments, the process further comprises a hydrogen donor, a base, and a solvent. For example, the process can further comprise formic acid, triethylamine and DMF.

In certain embodiments, the process further comprises a hydrogen donor and a solvent, as described above and herein, wherein the mixture comprises about 10% to about 80%, about 20% to about 75% or about 30% to about 70% hydrogen donor in solvent. In certain embodiments, the mixture comprises about 40% hydrogen donor in solvent (i.e., a ratio of about 2:5 hydrogen donor:solvent). In certain embodiments, the mixture comprises about 66% hydrogen donor in solvent (i.e., a ratio of about 2:1 hydrogen donor:solvent).

In certain embodiments, the process is conducted at a temperature of 0° C. to about 90° C., of about 25° C. to about 80° C., of about 0° C. to about 50° C., of about 20° C. to about 45° C., of about 10° C. to about 40° C., of about 15° C. to about 30° C., or of about 5° C. to about 20° C. In certain embodiments, the process is conducted at about room temperature (e.g., at a temperature of about 23° C. or about 25° C.). In some embodiments, the process is conducted at about 80° C. In other embodiments, the process is conducted at about 45° C. In other embodiments, the process is conducted at about 40° C. In other embodiments, the process is conducted at about 0° C. In some embodiments, the process is conducted at about 5° C. to about 20° C.

In certain embodiments, the process further comprises about 0.1 mol % to about 2.0 mol %, about 0.5 mol % to about 2.0 mol %, about 0.1 mol % to about 1.5 mol %, about 0.1 mol % to about 1.0 mol %, about 0.1 mol % to about 0.5 mol %, or about 0.2 mol % to about 0.5 mol % of the ruthenium transition metal catalyst (calculated from the molar amount of compound (I)). In certain embodiments, the process provides about 0.2 mol % of the ruthenium transition metal catalyst. In certain embodiments, the process provides about 0.25 mol % of the ruthenium transition metal catalyst. in other embodiments, the process provides about 0.5 mol % of the ruthenium transition metal catalyst. In certain embodiments, the process provides about 1 mol % of the ruthenium transition metal catalyst. In certain embodiments, the process provides about 1.5 mol % of the ruthenium transition metal catalyst.

In certain embodiments, the process further comprises removing residual ruthenium from the reaction mixture once the compound of Formula (II) has formed using a scavenger. Exemplary scavengers include, but are not limited to, silica based products from Phosphonics (SEA, STA3, POH1, SEM22, SEM26, SPM36F, SPM32 and MTCf), SiliCycle (SiliaBond-DMT, Si-Imidazole, Si-TAAcOH, Si-Diamine, Si-Triamine, Si-DMT, Si-TAAcONa, Si-Thiol and Si-Thiourea), fiber based materials from Johnson-Matthey (S-301, Smopex 111pp, Smopex 112v and Smopex 234), activated carbon (Norit E-supra) and silica gel (EMD). In certain embodiments, the scavenger is SiliaBond-DMT. In other embodiments, the scavenger is SPM32. In some embodiments, the scavenger is Si-Thiol. In some embodiments, the scavenger is selected from SEM22, SPM32, Si-Thiol, Si-DMT, and STA3.

In some embodiments, the scavenger amount is about 20 wt % to about 100 wt % based on a theoretical 100% yield of the compound of Formula (II), such as about 30 to about 50 wt %. In other embodiments, the scavenger amount is about 100 wt %. In some embodiments, the scavenger amount is 40 wt % and the reaction mixture is stirred with the scavenger present for about 10 to about 25 hours (e.g., about 20 hours). In certain embodiments, the scavenger is SPM32 at 50 wt %, and the reaction mixture is stirred with the scavenger present at 50° C. for about 10 hours.

In a non-limiting example, the synthesis of a compound of Formula (II) as described herein can be performed using about 0.25 mol % to about 2 mol % (e.g., about 1 mol %) ruthenium transition metal catalyst, about 2 vol. to about 20 vol. (e.g., about 10 vol.) hydrogen donor, about 0.02 mol % to about 0.1 mol % (e.g., about 0.05 mol %) base, at about 0° C. to about 20° C. (e.g., about 13° C.). In some embodiments, the synthesis of a compound of Formula (II) as described herein can be performed using about 0.5 mol % to about 2 mol % (e.g., about 0.5 mol % or about 1 mol %) ruthenium transition metal catalyst, such as (iii-g); about 2 vol. to about 20 vol. (e.g., about 2, 5, 6 or 10 vol.) hydrogen donor, such as iPrOH; about 0.05 equiv. to about 0.2 equiv. (e.g., about 0.1 or about 0.2 equiv.) base, such as KOiPr; about 3 vol. to about 10 vol. of organic solvent (e.g. about 5 vol.), such as 2-Me-THF; at about 5° C. to about 25° C. (e.g., about 20° C.). In some embodiments, the reaction proceeds for about 2 to about 10 hours (e.g., about 4 or about 7 hours).

Exemplification

The chemical entities described herein can be synthesized according to one or more illustrative schemes herein and/or techniques well known in the art.

Unless specified to the contrary, the reactions described herein take place at atmospheric pressure, generally within a temperature range from −10° C. to 200° C. Further, except as otherwise specified, reaction times and conditions are intended to be approximate, e.g., taking place at about atmospheric pressure within a temperature range of about −10° C. to about 110° C. over a period that is, for example, about 1 to about 24 hours; reactions left to run overnight in some embodiments can average a period of about 16 hours.

The terms “solvent,” “organic solvent,” or “inert solvent” each mean a solvent inert under the conditions of the reaction being described in conjunction therewith including, for example, benzene, toluene, acetonitrile, tetrahydrofuran (“THF”), dimethylformamide (“DMF”), chloroform, methylene chloride (or dichloromethane), diethyl ether, methanol, N-methylpyrrolidone (“NMP”), pyridine and the like. Unless specified to the contrary, the solvents used in the reactions described herein are inert organic solvents. Unless specified to the contrary, for each gram of the limiting reagent, one cc (or mL) of solvent constitutes a volume equivalent.

Isolation and purification of the chemical entities and intermediates described herein can be effected, if desired, by any suitable separation or purification procedure such as, for example, filtration, extraction, crystallization, column chromatography, thin-layer chromatography or thick-layer chromatography, or a combination of these procedures. Specific illustrations of suitable separation and isolation procedures are given by reference to the examples hereinbelow. However, other equivalent separation or isolation procedures can also be used.

When desired, the (R)- and (S)-isomers of the non-limiting exemplary compounds, if present, can be resolved by methods known to those skilled in the art, for example by formation of diastereoisomeric salts or complexes which can be separated, for example, by crystallization; via formation of diastereoisomeric derivatives which can be separated, for example, by crystallization, gas-liquid or liquid chromatography; selective reaction of one enantiomer with an enantiomer-specific reagent, for example enzymatic oxidation or reduction, followed by separation of the modified and unmodified enantiomers; or gas-liquid or liquid chromatography in a chiral environment, for example on a chiral support, such as silica with a bound chiral ligand or in the presence of a chiral solvent. Alternatively, a specific enantiomer can be synthesized by asymmetric synthesis using optically active reagents, substrates, catalysts or solvents, or by converting one enantiomer to the other by asymmetric transformation.

The compounds described herein can be optionally contacted with a pharmaceutically acceptable acid to form the corresponding acid addition salts. Also, the compounds described herein can be optionally contacted with a pharmaceutically acceptable base to form the corresponding basic addition salts.

In some embodiments, disclosed compounds can generally be synthesized by an appropriate combination of generally well known synthetic methods. Techniques useful in synthesizing these chemical entities are both readily apparent and accessible to those of skill in the relevant art, based on the instant disclosure. Many of the optionally substituted starting compounds and other reactants are commercially available, e.g., from Aldrich Chemical Company (Milwaukee, Wis.) or can be readily prepared by those skilled in the art using commonly employed synthetic methodology.

The discussion below is offered to illustrate certain of the diverse methods available for use in making the disclosed compounds and is not intended to limit the scope of reactions or reaction sequences that can be used in preparing the compounds provided herein.

The present disclosure now being generally described, it will be more readily understood by reference to the following examples, which are included merely for purposes of illustration and are not intended to limit the disclosure herein.

Example 1. Preparation of Ruthenium Transfer-Hydrogenation Catalyst (iii-g)

A. Preparation of Amino Alcohol (i-j)

To a mixture of 2-amino-2-methyl-propan-1-ol (200 g, 2.2 mol, 1 equiv) and water (1 volume) was added bromoethane (489 g, 4.4 mol, 2 equiv). The mixture was stirred for 24-48 hours at 40° C., then cooled to RT. 50% aqueous NaOH (1 vol) was added and then the mixture was extracted with dichloromethane. Concentration of the organic layer in vacuo, followed by crystallization from MTBE (5 vol), afforded the amino alcohol (i-j).

B. Preparation of Ru Amino Alcohol Catalyst (iii-g)

Into a three neck 3 L round bottom flask, equipped with Claisen adapter, temperature probe, gas inlet and outlet, condenser and heating mantle, were added (hexamethylbenzene)ruthenium chloride dimer (8.87 g, 13.27 mmol, 1 mole equiv) and 2-(N-ethylamino)-2-methyl-propan-1-ol (i-j) (6.22 g, 53.1 mmol, 4 mole equiv). The flask was evacuated and refilled with nitrogen for three times. 2-Propanol (1 L, 112 vol based on the Ru dimer), degassed by sparging with argon for 30 min, was added to the flask. To the stirred suspension, potassium isopropoxide (5.0% w/v in 2-PrOH, 52 ml, 27 mmol) was added at room temperature. The reaction mixture was heated to 50° C. and stirred at 50° C.±5° C. for 80 min. The heating was turned off and the reaction was allowed to cool to room temperature with stirring. In this way, the catalyst [(2-N-ethylamino)-2-methyl-propan-1-ol](hexamethylbenzene)ruthenium hydride (iii-g) was prepared for use in transfer-hydrogenation of a compound of formula (I).

Example 2. Transfer Hydrogenation of a Compound of Formula (I-a)

A. Preparation of a Compound of Formula (II-a)

A solution of the ketone (I-a) (1.825 kg, 3.54 mol) in 9.1 L 2-MeTHF was added to a 50 L jacketed reactor equipped with mechanical stirrer, 1000 mL addition funnel with ¼″ PTFE connecting tube (with a shutoff valve in-between) to a 3 L catalyst vessel. The solution was diluted with 2-PrOH (11 L). Potassium isopropoxide (5% w/v in 2-PrOH, 354 mmol, 700 mL) was added. The mixture was sparged with argon for 60 min. The catalyst (iii-g) (0.5 mole %, 11.04 g, 26.5 mmol) was added via the addition funnel. The mixture was stirred for 90 min under argon atmosphere at room temperature. An HPLC sample was prepared by removing 10 μl of the reaction mixture and diluting it into ACN (1 mL). The HPLC showed less than 1% of the starting material remained. PhosphonicS SPM32 resin (913.5 g, 50 wt % based on starting material) was added to the reaction mixture. The reactor was equipped with a reflux condenser, and the slurry was stirred for 18 h at 50° C. The mixture was cooled to room temperature (19° C.) and the scavenger was removed by filtration on a Buchner filter. The cake comprising (II-a) was washed with 2-MeTHF (2 volumes based on product 100% yield).

In order to remove the 2-PrOH from the isolated cake, five solvent chases with 2-Me-THF were carried out prior to the crystallization. A 50 L jacketed reactor was equipped with mechanical stirrer, distillation apparatus and connected to Huber. The reactor was marked for 5 vol and 20 vol solution. The solution of (II-a) was charged to the reactor. Vacuum was applied and the solution was heated to begin the distillation (40±5° C.). The solution was concentrated to 5 vol (9 L based on II-a). 2-Me-THF (15 vol, 27.5 L) was added, and vacuum was applied before restarting the heating. The solution was concentrated to 5 vol (9 L) by vacuum distillation (40±5 OC). The charging of 2-Me-THF (15 vol, 27.5 L) and concentration to 5 volumes was performed as described above four more times. The solution (9 L in 2-Me-THF) was added to the reactor. Acetonitrile (11 L, 6 volumes) was charged at 20±5° C. with stirring. The mixture was stirred at 20±5 OC for 60 min to initiate the crystallization. Water was added over 60 min (22 L, 12 vol) at 20±5° C., and then the mixture was stirred for 2 hours. The product (II-a) was isolated by filtration on Buchner filter. The cake was washed with 2/1 water/ACN (2 vol, 60 mL). The cake was kept on the filter for 60 min. The product was dried in a vacuum oven at 70° C. to afford (S)-(II-a) as a 99:1 β:α ratio of diastereomers.

B. Ru Scavenger Evaluation 1

To the mixture attained after stirring the components for 90 minutes at room temperature, 1 wt equivalent of the following scavengers was added and the resulting mixture was stirred for 18 h at 50° C. The mixture was then cooled to room temperature and filtered. The filtrate was concentrated in vacuo and the residue evaluated for Ru content by ICP-OES as shown in Table 6.

	TABLE 6
	Scavenger	Residual Ru
	None	3211	ppm
	SEM26	16	ppm
	SPM32	19	ppm
	MTCf	53	ppm
	JM S-301	4195	ppm
	JM Smopex 111pp	2704	ppm
	JM Smopex 112v	1048	ppm
	JM Smopex 234	229	ppm
	Norit	570	ppm
	None	1654	ppm
	Si-Imidazole	357	ppm
	Si-Diamine	653	ppm
	SiliaBond DMT	8	ppm
	Si-TAAcONa	316	ppm
	Si-Thiol	7	ppm
	Si-Thiourea	75	ppm
	Si-Triamine	639	ppm
	SPM36f	22	ppm

C. Ru Scavenger Evaluation 2

To a mixture of 500 mg of (II-a) where R¹=Bn, 1 wt equivalent of the following scavengers was added at 20° C. and the resulting mixture was stirred for 17 h at 50° C. The mixture was then cooled to room temperature and filtered. The filtrate was concentrated in vacuo and the residue was evaluated for Ru content by ICP-MS as shown in Table 7.

	TABLE 7
	Scavenger	Residual Ru
	None	1500	ppm
	SEM22	5.2	ppm
	SPM32	4.1	ppm
	STA3	46.1	ppm
	Si-Thiol	2.4	ppm
	Si-DMT	4.1	ppm

D. Ru Scavenger Evaluation 3

Using the procedure of Example 2C, the following scavengers were evaluated for residual Ru at three time points as shown in Table 8.

TABLE 8
Parameters	Test D.1	Test D.2	Test D.3	Test D.4	Test D.5	Test D.6
Scale (g of	20	20	5	5	5	5
(II-a))
Scavenger	SPM32	SPM32	SPM32	Si-Thiol	Si-Thiol	Si-Thiol
Amt.	0.3	0.3	0.5	0.2	0.3	0.5
Scavenger
(wt. equiv.)
Temp. (° C.)	20	50	50	50	50	50
Residual Ru	43.0/5	37.5/2	8/4	33/4	15/4	9/4
(ppm)/time
point 1 (h)
Residual Ru	36.4/10	25.0/6	5/10	21/10	8/10	5/10
(ppm)/time
point 2 (h)
Residual Ru	30.6/19	17.8/16	4/18	15/18	6/18	4/18
(ppm)/time
point 3 (h)

E. Reaction Scale Evaluation

The Example 2A procedure was performed using the following amounts of starting material (I-a) where R¹ is Bn and allowed to react with the Ru catalyst (iii-g) for the given reaction times. The diastereoselectivity of the resulting compound (II-a) is shown in Table 9.

	TABLE 9
			Reaction time
	Reaction scale		with 1 mole %	(II-a)
	(I-a)		Ru catalyst	β/α excess
	37 g	60	min	99.3/0.7
	60 g	90	min	99.3/0.7
	50 g	420	min	99/1
	39 g	90	min	99/1
	183 g	150	min	98.7/1.3
	1958 g	90	min	99/1

Example 3. Hydrogenation of a Compound of Formula (I-a) Using HCO₂H:Et₃N

A. General Reaction Conditions

A Schlenk flask was charged with (I-a, R¹=Bn) (0.5 g, 0.969 mmol) and (S,S)TsDPENRuCl₂(p-cymene) (15.7 mg, 0.025 mmol). The flask was put under argon, and 16 mL triethylamine was added, followed by 4 mL of formic acid. This mixture was heated to 75° C. for 24 h. The reaction was then analyzed by HPLC after 24 h indicating a (S)-(II-a) β/α ratio of 80:20.

B. Reaction Solvent Evaluation

A mixture of 140 mg of (I-a, R¹=Cbz) and 3.2 mg (S,S)TsDPENRuCl₂(p-cymene) was prepared in 1 mL 2-MeTHF and stirred until it became homogenous. To each of five vials was added 200 μL of this solution, to give five vials total with 28 mg of (I-a, R¹=Cbz) and 0.63 mg (S,S)TsDPENRuCl₂(p-cymene) in 200 μL 2-MeTHF. Then, to each vial was added 800 μL of a solvent as shown in Table 10. 100 μL of a 5:2 molar ratio solution of formic acid:triethylamine was added to each vial, and the mixture was stirred for 20 h at RT. The resulting β/α diastereomeric ratio of the product (II-a, R¹=Cbz) was determined by HPLC.

TABLE 10
		(II-a, R1 = Cbz)
Vial	Solvent	β/α ratio
1	2-MeTHF	91:9
2	DMF	95:5
3	MeOH	90:10
4	iPrOH	73:27
5	toluene	83:17

Example 4. Transfer-Hydrogenation of a Compound of Formula (I-g)

Using an analogous procedure to Example 2A, except ketone (I-g) was substituted for ketone (I-a), the Ru catalyzed transfer-hydrogenation afforded alcohol (R)-(II-g) as a 1:99 β:α ratio of diastereomers. LCMS: (M+H) 518.36.

Example 5. Transfer-Hydrogenation of a Compound of Formula (I-a) Using a Chiral Ru Catalyst

Using an analogous procedure to Example 2A, except that 20 mol % NaOiPr in iPrOH was used in place of 5% KOiPr in iPrOH, the following Ru chiral transfer-hydrogenation catalysts 1-7 were evaluated for reduction of (I-a) to (II-a) as shown in Table 11. The β-hydroxy isomer is (S)-(II-a) while the α-hydroxy isomer is the diastereomeric (R)-(II-a).

TABLE 11
Catalyst                         (II-a) β:α ratio
1. (S,S)TsDPEN-RuCl(p-cymene) (R1 = Cbz) 92:8
2. ((1R,2S)aminoindanol)RuCl(p-cymene) (R1 = Cbz) 63:27
3. ((1S,2R)aminoindanol)RuCl(p-cymene) (R1 = Cbz) 51:49
4. (Ph3P)RuCl2((+)-(R)-Fe-oxazoline) (R1 = Bn) 44:56
5. (Ph3P)RuCl2((−)-(S)-Fe-oxazoline) (R1 = Bn) 52:48
6. ((S,R)JOSIPHOS)RuCl2(DMF)n (R1 = Cbz) 4:96
7. ((R,S)JOSIPHOS)RuCl2(DMF)n (R1 = Cbz) 4:96

Example 6. Transfer-Hydrogenation of a Compound of Formula (I-a) Using a Chiral Ru Bis-Phosphonite Catalyst

Into a three-neck 500 ml round bottom flask, equipped with Claisen adapter, temperature probe, gas inlet and outlet, condenser and heating mantle, were added (p-cymene)ruthenium chloride dimer 43.3 mg, 0.071 mmol, 0.020 mole equiv) and (11bS,11′bS)-4,4′-(9,9-Dimethyl-9H-xanthene-4,5-diyl)bis-dinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin (302 mg, 0.36 mmol, 0.10 mole equiv). The flask was evacuated and refilled with nitrogen for three times. 2-Propanol (238 ml, 160 vol based on the Ru dimer), degassed by sparging with argon for 30 min, was added to the flask. The reaction mixture was heated to 80° C. To the stirred suspension, potassium t-butoxide (1 M in 2-PrOH, 3.6 ml, 3.6 mmol, 1 equiv) was added and the reaction was stirred at 40° C. for hours. A solution of the ketone (I-a) 1.83 g, 3.6 mmol, 1 equivalent) in 18 ml iPrOH was added and the mixture was stirred for 64 hours at 40° C. HPLC analysis of the reaction mixture indicated that the product (S)-(II-a) was a 97:3 β:α ratio of diastereomers.

This procedure was repeated with 70 volumes of iPrOH based on the Ru dimer, affording (S)-(II-a) as a 95:5 β:α ratio of diastereomers, and 35 volumes of iPrOH based on the Ru dimer, affording (S)-(II-a) as an 82:18 β:α ratio of diastereomers.

Example 7. Transfer-Hydrogenation of a Compound of Formula (I-a) Using a Ru-Ephedrine Catalyst

A. Exemplary Formation of Ru-Ephedrine Catalysts

To a mixture of (mesitylene)ruthenium chloride dimer (60.6 mg, 0.104 mmol, 0.5 mole equiv) and (1S,2R)-ephedrine HCl (62.7 mg, 0.311 mmol, 1.5 mole equiv) was added degassed iPrOH (14.8 ml). To the stirred suspension, Et₃N (300 μl, 2.15 mmol) was added to give a 4.01 mg Ru/ml solution. The reaction mixture was heated to 85° C. and stirred at 85° C. for two hours. The heating was turned off and the reaction allowed to cool to room temperature with stirring. In this way, the (mesitylene)RuCl-ephedrine catalyst (10) was prepared for use in the transfer-hydrogenation of a compound of formula (I). In addition, Ru chloride dimers having different arene ligands were used to prepare the following (arene)RuCl-ephedrine catalysts (11) to (17) in an analogous manner:

B. Transfer-Hydrogenation of a Compound of Formula (I-a) Using Ru Catalysts 11-17

To (I-a) (10.00 g, 19.4 mmol) was added iPrOH (100.0 mL, 10.0 vol) and the mixture was stirred. RuCl-ephedrine catalyst (10) (7.1 mL, 28.5 mg Ru, 0.0488 mmol, 0.25 mol % Ru dimer) was added, followed by 1.94 mL of 1M KOtBu in tBuOH (1.94 mmol, 10 mol %). The mixture was stirred for 45 min at room temperature. Then, EtOAc (135 mL) was added, followed by 20 mL of 5-6 N HCl in isopropanol, and the mixture was stirred for 16 h. After concentrating in vacuo to a net weight of 5 weights, filtering through a fritted funnel, and further concentration, (S)-(II-a) was isolated as its HCl salt with a β:α diastereoselectivity ratio of 98:2 by HPLC analysis.

Using analogous procedures to Examples 7A and 7B, compounds of Formula (II-a) were prepared with Ru-ephedrine catalysts 10, 12-15, and 17 with the diastereoselctivity indicated in Table 12.

TABLE 12
	Catalyst: (II-a) β:α	Catalyst: (II-a) β:α
	ratio with 1R,2S	ratio with 1S,2R	mol %
Arene	ephedrine ligand	ephedrine ligand	Ru used
mesitylene	(11): —	(10): 96.5:3.5	0.5%
hexamethylbenzene	(12): 96:4	(13): 98.8:1.2	1.5%
p-cymene	(14): 75:25	(15): 85:15	0.5%
benzene	(16): —	(17): 52:48	0.5%

B.1 Effect of Temperature and Catalyst Loading on the Diastereoselectivity of a Compound of Formula (II-a)

Using an analogous procedure to Example 7B, Ru-(1S,2R)-ephedrine transfer-hydrogenation catalysts having either mesitylene (10) or hexamethylbenzene (13) arene ligands were employed to determine the effect of temperature and catalyst loading (mol % based on amount of (I-a)) on diastereoselectivity in the transfer-hydrogenation of a compound of Formula (I-a) where R¹ is Bn. The resulting diastereoselectivity of compounds of Formula (II-a) are summarized in Table 13.

TABLE 13
	Ru
	Catalyst
	Loading	Temperature	(II-a)
Arene	(mol %)	(° C.)	β:α ratio
mesitylene (10)	0.5%	23	96.5:3.5
mesitylene (10)	0.5%	0	97:3
hexamethylbenzene (13)	0.2%	45	89:11
hexamethylbenzene (13)	0.5%	23	98.8:1.2
hexamethylbenzene (13)	0.5%	0	—

Example 8. Transfer-Hydrogenation of a Compound of Formula (I-a) Using a Chiral Ru Catalyst

Using a procedure analogous to Example 7A, the following chiral Ru transfer-hydrogenation catalysts were prepared (Formulas 18 to 92) using the (arene)ruthenium chloride dimer and ligand given in Table 14. Using a procedure analogous to Example 7B, these Ru transfer-hydrogenation catalysts were used to reduce a ketone of Formula (I-a) where R¹ is Bn. The diasteroselectivity of the resulting alcohol of Formula (II-a) is given in Table 14.

TABLE 14
For-			(II-a)
mu-			β/α
la	Arene	Ligand	ratio
(18)	benzene		45/55
(19)	benzene		44/56
(20)	benzene		39/61
(21)	benzene		38/62
(22)	benzene		38/62
(23)	benzene		35/65
(24)	benzene		28/72
(25)	benzene		30/70
(26)	benzene		43/57
(27)	benzene		48/52
(28)	benzene		54/46
(29)	benzene		51/49
(30)	benzene		45/55
(31)	benzene		50/50
(32)	benzene		44/56
(33)	benzene		39/61
(34)	benzene		43/57
(35)	benzene		36/64
(36)	p-cymene		65/35
(37)	p-cymene		71/29
(38)	p-cymene		46/54
(39)	p-cymene		27/73
(40)	p-cymene		64/36
(41)	p-cymene		37/63
(42)	p-cymene		58/42
(43)	p-cymene		48/52
(44)	p-cymene		70/30
(45)	p-cymene		71/29
(46)	p-cymene		48/52
(47)	p-cymene		47/53
(48)	p-cymene		50/50
(49)	p-cymene		49/51
(50)	p-cymene		64/36
(51)	p-cymene		55/45
(52)	p-cymene		80/20
(53)	p-cymene		85/15
(54)	p-cymene		71/29
(55)	mesitylene		66/34
(56)	mesitylene		68/32
(57)	mesitylene		67/33
(58)	mesitylene		67/33
(59)	mesitylene		62/38
(60)	mesitylene		79/21
(61)	mesitylene		75/25
(62)	mesitylene		84/16
(63)	mesitylene		67/33
(64)	mesitylene		93/7
(65)	mesitylene		81/19
(66)	mesitylene		80/20
(67)	mesitylene		70/30
(68)	mesitylene		69/31
(69)	mesitylene		25/75
(70)	mesitylene		57/43
(71)	mesitylene		51/49
(72)	mesitylene		63/37
(73)	mesitylene		58/42
(74)	hexamethylbenzene		89/11
(75)	hexamethylbenzene		91/9
(76)	hexamethylbenzene		83/17
(77)	hexamethylbenzene		75/25
(78)	hexamethylbenzene		86/14
(79)	hexamethylbenzene		45/55
(80)	hexamethylbenzene		91/9
(81)	hexamethylbenzene		86/14
(82)	hexamethylbenzene		95/5
(83)	hexamethylbenzene		97/3
(84)	hexamethylbenzene		68/32
(85)	hexamethylbenzene		67/33
(86)	hexamethylbenzene		92/8
(87)	hexamethylbenzene		89/11
(88)	hexamethylbenzene		88/12
(89)	hexamethylbenzene		97/3
(90)	hexamethylbenzene		81/19
(91)	hexamethylbenzene		93/7
(92)	hexamethylbenzene		89/11

Example 9. Transfer-Hydrogenation of a Compound of Formula (I-a) Using an Achiral Ru Catalyst

Using an analogous procedure to Example 1B, the following achiral Ru transfer-hydrogenation catalysts (93, iii-g, iii-m-iii-y) were prepared using an achiral ligand and an (arene)dichlororuthenium dimer. The transfer-hydrogenation reactions of a compound of Formula (I-a) where R¹ is Bn with these catalysts to afford a compound of Formula (II-a) were performed using an analogous procedure to Example 2A, except that the Ru catalyst loading was 1 mol % or 2 mol %. The diasteroselectivity of the resulting compounds of Formula (II-a) is given in Table 14.

TABLE 14
Formula	Arene	Ligand	(II-a) β:α ratio
(93)	mesitylene		75:25
iii-g	hexamethylbenzene		99.1:0.9
iii-m	mesitylene		59:41
iii-n	mesitylene		90:10
iii-o	mesitylene		55:45
iii-p	mesitylene		56:44
iii-q	mesitylene		40:60
iii-r	mesitylene		60:40
iii-s	hexamethylbenzene		96:4
iii-t	hexamethylbenzene		94:6
iii-u	hexamethylbenzene		52:48
iii-v	hexamethylbenzene		98.7:1.3
iii-w	hexamethylbenzene		91:9
iii-x	p-cymene		82:18
iii-y	benzene		37:63

EQUIVALENTS

Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments described herein. Such equivalents are intended to be encompassed by the following claims.

Claims

1. A process for preparing a compound of formula (II):

2. The process of claim 1, wherein the compound of formula (I) is a compound of formula (I-AA):

3. The process of claim 2 wherein the ring carbon atom that is directly attached to the hydroxyl group on the compound of formula (II-AA) has an (S) stereochemical configuration and R11 is hydrogen in the β-position.

4. The process of claim 1, wherein Ra and Rb are both —CH3 and Rc is —CH2CH3.

5. The process according to claim 1, wherein the benzene ligand with Rh-Rm is selected from benzene, mesitylene, p-cymene, and hexamethylbenzene.

6. The process according to claim 5, wherein the ruthenium transfer-hydrogenation catalyst is generated from (hexamethylbenzene)ruthenium chloride dimer and an achiral amino alcohol.

7. The process according to claim 1, wherein the ruthenium transfer-hydrogenation catalyst is of formula (iii-a):

8. The process according to claim 7, wherein the ruthenium transfer-hydrogenation catalyst is of the formula (iii-g):

9. The process of claim 1, wherein Ra and Rb are each methyl, Rc is ethyl, each of Rh, Ri, Rj, Rk, Rl, and Rm is methyl, and Xa is Cl−.

10. The process of claim 1, wherein the hydrogen donor is an organic alcohol.

11. The process of claim 10, wherein the reducing is carried out in an ether solvent.

12. The process of claim 11, wherein the reducing is carried out at a temperature of about 10° C. to about 40° C.

13. The process of claim 11, wherein the reducing is carried out in the presence of base.