Neuroactive substituted cyclopenta[b]phenanthrenes as modulators for GABA type-A receptors

BACKGROUND OF THE DISCLOSURE

The present disclosure is generally directed to novel compounds having utility as an anesthetic and/or in the treatment of disorders relating to GABA function and activity. More specifically, the present disclosure is directed to cyclopenta[b]phenanthrenes having a substituted tetracyclic structure that are neuroactive and suitable for use as an anesthetic, as well as pharmaceutically acceptable salts thereof, and pharmaceutical compositions containing them.

Gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter of the central nervous system. GABA activates two types of receptors, the inotropic GABA_Aand the metabotropic GABA_Breceptor. Activation of the GABA_Breceptor by GABA causes hyperpolarization and a resultant inhibition of neurotransmitter release. The GABA_Areceptor subtype regulates neuronal excitability and rapid mood changes, such as anxiety, panic, and stress response. GABA_Areceptors are chloride ion channels; as a result, activation of the receptor induces increased inward chloride ion flux, resulting in membrane hyperpolarization and neuronal inhibition. Drugs that stimulate GABA_Areceptors, such as benzodiazepines and barbiturates, have anticonvulsive effects (by reducing neuronal excitability and raising the seizure threshold), as well as anxiolytic and anesthetic effects.

The effect of certain steroids on GABA_Areceptors has been well-established. As a result, researchers continue to pursue the discovery and synthesis of neuroactive steroids that may act as anesthetics and/or that may serve to provide treatment for disorders related to GABA function. For example, it is now widely accepted that the intravenous anesthetic alphaxalone (Compound A, below) causes general anesthesia in humans because it allosterically increases chloride currents mediated by GABA acting at GABA_Areceptors in the brain. However, the various structural features that enable this compound to function in the way it does have, to-date, not been fully understood.

embedded image

In particular, the effect of changing the manner in which the four rings of neurosteroids are connected and the locations of the substituents on them is not completely understood. It was shown for two compounds that moving the B-ring of the steroid cyclopenta[a]phenanthrene ring system to obtain the cyclopenta[b]phenanthrene ring system could yield active compounds as shown in FIG. 1 by creating FIG. 1C from FIG. 1A and by creating FIG. 1D from FIG. 1B (Scaglione, et al., “Neurosteroid Analogues. 14. Alternative Ring System Scaffolds: GABA Modulatory and Anesthetic Actions of Cyclopenta[b]phenanthrenes and Cyclopenta[b]anthracenes,” J. Med. Chem., Vol. 51, Pages 1309-1318 (2008)). The other structural details of additional neuroactive cyclopenta[b]phenanthrenes, however, are unknown and are the subject of this disclosure.

In addition to anesthetic properties, neuroactive cyclopenta[b]phenanthrenes may be used to treat disorders related to GABA function. For example, neuroactive cyclopenta[b]phenanthrenes may be used as sedative-hypnotics, exhibiting benzodiazepine-like actions, inducing reduced sleep latency and increased non-REM sleep with only small changes in slow wave and REM sleep. Further, drugs that enhance GABA responses are often used to treat anxiety in humans. Thus, it might be expected that GABA-potentiating cyclopenta[b]phenanthrenes would exhibit anxiolytic effects. Neuroactive cyclopenta[b]phenanthrenes may also be used to treat depression, given that accumulating evidence suggests that patients with major depression have decreased levels of GABAergic neurosteroids and that certain treatments for depression alter levels of these neurosteroids. Although GABA is not typically thought to play a critical role in the biology of depression, there is evidence that low GABAergic activity may predispose one to mood disorders. Finally, inhibition of NMDA receptors and enhancement of GABA_Areceptors appear to play important roles in mediating the acute effects of ethanol in the nervous system, while related studies suggest that GABAergic neurosteroids may be involved in some of the pharmacological effects of ethanol and that neuroactive neurosteroids may be useful in treating ethanol withdrawal. Thus, cyclopenta[b]phenanthrenes as analogues of endogenous neurosteroids may be useful for treating these conditions.

In view of the foregoing, it is clear that there are a number of potentially advantageous uses for cyclopenta[b]phenanthrenes. As a result, there is a continuing need for the further synthesis and understanding of new neuroactive cyclopenta[b]phenanthrenes, particularly those having utility as an anesthetic and/or in the treatment of a disorder relating to GABA function and activity.

SUMMARY OF THE DISCLOSURE

In one aspect, the present disclosure is directed to a compound having a structure of Formula (I):

embedded image

or a pharmaceutically acceptable salt thereof;

wherein:

R₁is H, ═O, ═CHCN, ═CHCO₂R_z, where R_zis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, β-CN, β-OH, β-OR_y, where R_yis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, β-NO₂, spiroepoxy, or C(O)R_x, where R_xis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl;

R₂is H, ═O, ═CHCN, ═CHCO₂R_w, where R_wis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, β-CN, β-OH, β-OR_v, where R_vis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, β-NO₂, spiroepoxy, or C(O)R_u, where R_uis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl;

R₃is H, ═O, ═CHCN, ═CHCO₂R_t, where R_tis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, —CN, β-OH, β-OR_s, where R_sis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, β-NO₂, spiroepoxy, or C(O)R_r, where R_ris optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl;

R₄is H, optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl;

R₅is H, CO₂R_q, where R_qis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl, CH₂OR_p, where R_pis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl, C(O)R_o, where R_ois optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl, C(O)NHR_n, where R_nis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl, CH₂NHR_m, where R_n, is optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl, CH₂N(CH₃)₂, or CH₂N(CH₂CH₃)₂;

R₆is H, ═O, N(CH₃)₂, N(CH₂CH₃)₂, OR_l, where R_lis optionally substituted C_rC₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl, or NR_k, where R_kis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl;

R₇is H, ═O, N(CH₃)₂, N(CH₂CH₃)₂, OR_j, where R_jis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl, or NR_i, where R_iis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl;

R₈is H, N(CH₃)₂, N(CH₂CH₃)₂, optionally substituted morpholinyl, or OR_h, where R_his optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl;

R₉is H, optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl;

R₁₀is H, optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl;

R₁₁is H or C(O)R_g, where R_gis optionally substituted C₁-C₂₀alkyl, optionally substituted C₂-C₂₀alkenyl, or optionally substituted C₂-C₂₀alkynyl;

- - - denotes an optional, additional C—C bond, resulting in either a C═C bond between, C₁-C₂, C₄-C_4a, C_4a-C₅, C₈-C₉, or C₉-C₁₀, with the provisos that when present between: (i) C₄-C_4a, the C_4a—H substituent is not present; (ii) C_4a-C₅, the C_4a—H substituent is not present and R₇is other than ═O; (iii) C₉-C₁₀, R₁is other than ═O, ═CHCN or ═CHCO₂R_z, and R₂is other than ═O, ═CHCN or ═CHCO₂R_w; and, (iv) C₈-C₉, R₂is other than ═O, ═CHCN or ═CHCO₂R_w, and R₃is other than ═O, ═CHCN or ═CHCO₂R_t; and,

with the proviso that:

when C_4a—H is in the α-configuration, R₄=methyl and R₁=R₂=R₅=R₆=R₇=R₈=R₉=R₁₀=R₁₁is H, R₃is other than ═O or spiroepoxy.

In another aspect, the present disclosure is directed to a compound having a structure of Formula (II):

embedded image

or a pharmaceutically acceptable salt thereof;

wherein:

R₁is H, ═O, ═CHCN, ═CHCO₂R_z, where R_zis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, α-CN, α-OH, α-OR_y, where R_yis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, α-NO₂, spiroepoxy, or C(O)R_x, where R_xis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl;

R₂is H, ═O, ═CHCN, ═CHCO₂R_w, where R_wis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, α-CN, α-OH, α-OR_v, where R_vis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, α-NO₂, spiroepoxy, or C(O)R_u, where R_uis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl;

R₃is H, ═O, ═CHCN, ═CHCO₂R_t, where R_tis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, α-CN, α-OH, α-OR_s, where R_sis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, α-NO₂, spiroepoxy, or C(O)R_r, where R_ris optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl;

R₄is H, optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl;

R₅is H, CO₂R_q, where R_qis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl, CH₂OR_p, where R_pis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl, C(O)R_o, where R_ois optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl, C(O)NHR_n, where R_nis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl, CH₂NHR_m, where R_mis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl, CH₂N(CH₃)₂, or CH₂N(CH₂CH₃)₂;

R₆is H;

R₉is H, optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl;

R₁₀is H, optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl;

R₁₁is H or C(O)R_g, where R_gis optionally substituted C₁-C₂₀alkyl, optionally substituted C₂-C₂₀alkenyl, or optionally substituted C₂-C₂₀alkynyl;

R₁₂is H, N(CH₃)₂, N(CH₂CH₃)₂, optionally substituted morpholinyl, or OR_h, where R_his optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl; and,

The present disclosure is still further directed to a pharmaceutical composition comprising a therapeutically effective amount of one or more of the above-noted cyclopenta[b]phenanthrenes or pharmaceutically acceptable salts thereof, and optionally a pharmaceutically acceptable carrier. The present disclosure also provides kits comprising cyclopenta[b]phenanthrenes, salts thereof, and/or pharmaceutical compositions thereof.

The present disclosure further provides methods of inducing anesthesia in a subject in need thereof, the method comprising administering to the subject a therapeutically effective amount of one or more of the above-noted cyclopenta[b]phenanthrenes, or pharmaceutically acceptable salts thereof, or a pharmaceutical composition thereof.

The present disclosure further provides methods of treating disorders related to GABA function in a subject in need thereof, the method comprising administering to the subject a therapeutically effective amount of one or more of the above-noted cyclopenta[b]phenanthrenes, or pharmaceutically acceptable salts thereof, or a pharmaceutical composition thereof. In certain embodiments, the disorder is selected from the group consisting of insomnia, mood disorders, convulsive disorders, Fragile X syndrome, anxiety, or symptoms of ethanol withdrawal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an exemplary embodiment of a cyclopenta[a]phenanthrene.

FIG. 1B is an exemplary embodiment of a cyclopenta[a]phenanthrene.

FIG. 1C is an exemplary embodiment of a cyclopenta[b]phenanthrene.

FIG. 1D is an exemplary embodiment of a cyclopenta[b]phenanthrene.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

In accordance with the present disclosure, it has been discovered that compounds having certain substituted cyclopenta[b]phenanthrene structures are neuroactive and are also suitable for use as anesthetics and in the treatment of disorders associated with GABA function, as well as pharmaceutically acceptable salts thereof. The compounds may be used, for example, as an effective continuous infusion sedative for non-surgical procedures (e.g., colonoscopy). The compounds also offer advantages over anesthetics known in the art, such as a lower likelihood for bacterial contamination, as well as an improved relationship with solubilizing agents.

1A. CYCLOPENTA[B]PHENANTHRENE STRUCTURE

Generally speaking, in one embodiment, the cyclopenta[b]phenanthrene of the present disclosure has a tetracyclic, fused ring structure (an embodiment of which is illustrated and discussed in greater detail below), wherein the C₃-position of the A ring has a hydroxyl or an ester substituent in the alpha configuration, the C₈position has a substituent attached thereto selected from the group consisting of H, ═O, ═CHCN, ═CHCO₂R_t, where R_tis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, —CN, β-OH, β-OR_s, where R_sis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, β-NO₂, spiroepoxy, and C(O)R_r, where R_ris optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl.

More particularly, however, the present disclosure is directed, in certain embodiments, to a cyclopenta[b]phenanthrene having the structure of Formula (I):

embedded image

or a pharmaceutically acceptable salt thereof;

wherein:

R₂is H, ═O, ═CHCN, ═CHCO₂R_w, where R_wis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, β-CN, δ-OH, β-OR_v, where R_vis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, β-NO₂, spiroepoxy, or C(O)R_u, where R_uis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl;

R₄is H, optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl;

R₅is H, CO₂R_q, where R_qis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl, CH₂OR_p, where R_pis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl, C(O)R_o, where R_ois optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl, C(O)NHR_n, where R_nis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl, CH₂NHR_m, where R_mis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl, CH₂N(CH₃)₂, or CH₂N(CH₂CH₃)₂;

R₆is H, ═O, N(CH₃)₂, N(CH₂CH₃)₂, OR_l, where R_lis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl, or NR_k, where R_kis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, optionally or substituted aryl;

R₉is H, optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl;

R₁₀is H, optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl;

R₁₁is H or C(O)R_g, where R_gis optionally substituted C₁-C₂₀alkyl, optionally substituted C₂-C₂₀alkenyl, or optionally substituted C₂-C₂₉alkynyl;

with the proviso that:

when C_4a—H is in the α-configuration, R₄=methyl and R₁=R₂=R₅=R₆=R₇=R₈=R₉=R₁₀=R₁₁is H, R₃is other than ═O or spiroepoxy.

As generally defined above, R₁is H, ═O, ═CHCN, ═CHCO₂R_z, where R_zis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, β-CN, β-OH, β-OR_y, where R_yis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, δ-NO₂, spiroepoxy, or C(O)R_x, where R_xis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl. In a preferred embodiment, R₁is H.

As generally defined above, R₂is H, ═O, ═CHCN, ═CHCO₂R_w, where R_wis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, β-CN, β-OH, δ-OR_v, where R_vis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, β-NO₂, spiroepoxy, or C(O)R_u, where R_uis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl. In a preferred embodiment, R₂is H.

As generally defined above, R₃is H, ═O, ═CHCN, ═CHCO₂R_t, where R_tis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, —CN, β-OH, δ-OR_s, where R_sis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, β-NO₂, spiroepoxy, or C(O)R_r, where R_ris optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl. In certain embodiments, R₃is ═CHCN. In other certain embodiments, R₃is β-NO₂. In yet other certain embodiments, R₃is ═O. In other certain embodiments, R₃is spiroepoxy. In other certain embodiments, R₃is β-CN. In still other certain embodiments, R₃is C(O)CH₃.

As generally defined above, R₄is H, optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl. In a preferred embodiment, R₄is methyl. R₄is in the beta configuration.

As generally defined above, R₅is H, CO₂R_q, where R_qis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl, CH₂OR_p, where R_pis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl, C(O)R_o, where R_ois optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl, C(O)NHR_o, where R_nis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl, CH₂NHR_m, where R_mis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl, CH₂N(CH₃)₂, or CH₂N(CH₂CH₃)₂. In certain embodiments, the optionally substituted aryl is optionally substituted phenyl or naphthyl. In a preferred embodiment, R₅is H. R₅is in the beta configuration.

As generally defined above, R₆is H, ═O, N(CH₃)₂, N(CH₂CH₃)₂, OR_l, where R_lis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl, or NR_k, where R_kis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl. In certain embodiments, the optionally substituted aryl is optionally substituted phenyl or naphthyl. In a preferred embodiment, R₆is H.

As generally defined above, R₇is H, ═O, N(CH₃)₂, N(CH₂CH₃)₂, OR_j, where R_jis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl, or NR_i, where R_iis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl. In certain embodiments, the optionally substituted aryl is optionally substituted phenyl or naphthyl. In a preferred embodiment, R₇is H.

As generally defined above, R₈is H, N(CH₃)₂, N(CH₂CH₃)₂, optionally substituted morpholinyl, or OR_h, where R_his optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl. In certain embodiments, the optionally substituted aryl is optionally substituted phenyl or naphthyl. In a preferred embodiment, R₈is H. R₈is in the beta configuration.

As generally defined above, R₉is H, optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl. In certain embodiments, the optionally substituted aryl is optionally substituted phenyl. In other certain embodiments, the optionally substituted alkyl is alkyl aryl, such as alkyl benzyl. In a preferred embodiment, R₉is H. R₉is in the beta configuration.

As generally defined above, R₁₀is H, optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl. In a preferred embodiment, R₁₀is H. In another preferred embodiment, R₁₀is methyl. R₁₀is in the beta configuration.

As generally defined above, R₁₁is H or C(O)R_g, where R_gis optionally substituted C₁-C₂₀alkyl, optionally substituted C₂-C₂₀alkenyl, or optionally substituted C₂-C₂₀alkynyl. In one embodiment, R_gis optionally substituted C₁-C₁₅alkyl, preferably optionally substituted C₁-C₁₀alkyl, more preferably optionally substituted C₁-C₄alkyl. In another embodiment, R_gis optionally substituted C₁-C₁₅alkenyl, preferably optionally substituted C₁-C₁₀alkenyl, more preferably optionally substituted C₁-C₄alkenyl. In yet another embodiment, R_gis optionally substituted C₁-C₁₅alkynyl, preferably optionally substituted C₁-C₁₀alkynyl, more preferably optionally substituted C₁-C₄alkynyl. In a preferred embodiment, R₁₁is H.

In one embodiment, the C_4a—H is in the alpha configuration. In another embodiment, the C_4a—H is in the beta configuration.

As generally defined above, - - - denotes an optional, additional C—C bond, resulting in either a C═C bond between, C₁-C₂, C₄-C_4a, C_4a-C₅, C₈-C₉, or C₉-C₁₀, with the provisos that when present between: (i) C₄-C_4a, the C_4a—H substituent is not present; (ii) C_4a-C₅, the C_4a—H substituent is not present and R₇is other than ═O; (iii) C₉-C₁₀, R₁is other than ═O, ═CHCN or ═CHCO₂R_z, and R₂is other than ═O, ═CHCN or ═CHCO₂R_w; and, (iv) C₈-C₉, R₂is other than ═O, ═CHCN or ═CHCO₂R_w, and R₃is other than ═O, ═CHCN or ═CHCO₂R_t.

In one embodiment, a double bond is present between C₄-C_4a. In another embodiment, a double bond is present between C_4a-C₅. When a double bond is present between either C₄-C_4aor C_4a-C₅, the C_4a—H is not present. Further, when a double bond is present between C_4a-C₅, R₇is other than ═O.

In certain embodiments, a double bond is present between C₁-C₂. In other certain embodiments, a double bond is present between C₈-C₉. When a double bond is present between C₈-C₆, R₃is other than ═O, ═CHCN or ═CHCO₂R_tand R₂is other than ═O, ═CHCN or ═CHCO₂R_w. In other certain embodiments, a double bond is present between C₉-C₁₀. When a double bond is present between C₉-C₁₀, R₂is other than ═O, ═CHCN or ═CHCO₂R_wand R₁is other than ═O, ═CHCN or ═CHCO₂R_z.

In one embodiment a double bond is present between C₈-C₉and R₃is —CN.

The compound of Formula (I) is subject to the proviso that when C_4a—H is in the α-configuration, R₄=methyl and R₁=R₂=R₅=R₆=R₇=R₈=R₉=R₁₀=R₁₁is H, R₃is other than ═O or spiroepoxy.

It is to be noted that the present disclosure contemplates and is intended to encompass all of the various combinations and permutations (i.e., combinations of substituent options, locations and stereochemical configurations) possible here.

For example, in various embodiments, compounds of the present disclosure have the formula of (I-a):

embedded image

wherein:

R₁₀is H, optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl; and,

- - - denotes an optional C—C bond, resulting in a C═C bond between C₈-C₉, with the proviso that when present, R₃is other than ═O, ═CHCN or ═CHCO₂R_t;

and, with proviso that when C_4a—H is in the α-configuration, R₄=methyl and R₁=R₂=R₅=R₆=R₇=R₈=R₉=R₁₀=R₁₁is H, R₃is other than ═O or spiroepoxy.

As generally defined above in Formula (I-a), R₃is H, ═O, ═CHCN, ═CHCO₂R_t, where R_tis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, —CN, β-OH, β-OR_s, where R_sis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, β-NO₂, spiroepoxy, or C(O)R_r, where R_ris optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl. In certain embodiments, R₃is ═CHCN. In other certain embodiments, R₃is β-NO₂. In yet other certain embodiments, R₃is ═O. In other certain embodiments, R₃is spiroepoxy. In other certain embodiments, R₃is β-CN. In still other certain embodiments, R₃is C(O)CH₃.

As generally defined above in Formula (I-a), R₁₀is H, optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl. In a preferred embodiment, R₁₀is methyl. In another preferred embodiment, R₁₀is H. R₁₀is in the beta configuration.

As generally defined above in Formula (I-a), - - - denotes an optional C—C bond, resulting in a C═C bond between C₈-C₉. In one embodiment a double bond is present between C₈-C₉. When a double bond is present between C₈-C₉in Formula (I-a), R₃is —CN.

In one embodiment, the C_4a—H is in the alpha configuration. In another embodiment, the C_4a—H is in the beta configuration.

Formula (I-a) is subject to the proviso that when C_4a—H is in the α-configuration, R₄=methyl and R₁=R₂=R₅=R₆=R₇=R_s=R₉=R₁₀=R₁₁is H, R₃is other than ═O or spiroepoxy.

Accordingly, as noted, the cyclopenta[b]phenanthrenes of Formulas (I) and (I-a) may encompass a number of various structures in accordance with the present disclosure, including all of the various combinations and permutations (i.e., combinations of substituent options, locations and stereochemical configurations) possible here.

Exemplary compounds of Formula (I) include, but are not limited to:

embedded image

and pharmaceutically acceptable salts thereof.

In this regard it is to be noted that the structures provided above are of various exemplary embodiments. As such, they should not be viewed in a limiting sense.

1B. CYCLOPENTA[B]PHENANTHRENE STRUCTURE

Generally speaking, in another embodiment, the cyclopenta[b]phenanthrene of the present disclosure has a tetracyclic, fused ring structure (an embodiment of which is illustrated and discussed in greater detail below), wherein the C₃-position of the A ring has a hydroxyl or an ester substituent in the beta configuration, the C₈position has a substituent attached thereto selected from the group consisting of H, ═O, ═CHCN, ═CHCO₂R_t, where R_tis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, α-CN, α-OH, α-OR_s, where R_sis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, α-NO₂, spiroepoxy, and C(O)R_r, where R_ris optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl; and the C₉position has a substituent attached thereto selected from the group consisting of H, ═O, ═CHCN, ═CHCO₂R_w, where R_wis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, α-CN, α-OH, α-OR_v, where R_vis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, α-NO₂, spiroepoxy, and C(O)R_u, where R_uis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl.

More particularly, however, the present disclosure is directed, in certain embodiments, to a cyclopenta[b]phenanthrene having the structure of Formula (II):

embedded image

or a pharmaceutically acceptable salt thereof;

wherein:

R₄is H, optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl;

R₅is H, CO₂R_q, where R_qis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl, CH₂OR_p, where R_pis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl, C(O)R_o, where R_ois optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl, C(O)NHR_n, where R_nis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl, CH₂NHR_m, where R_mis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl, CH₂N(CH₃)₂, or CH₂N(CH₂CH₃)₂;

R₆is H;

R₉is H, optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl;

R₁₀is H, optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl;

R¹¹is H or C(O)R_g, where R_gis optionally substituted C₁-C₂₀alkyl, optionally substituted C₂-C₂₀alkenyl, or optionally substituted C₂-C₂₀alkynyl;

As generally defined above, R₁is H, ═O, ═CHCN, ═CHCO₂R_z, where R_zis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, α-CN, α-OH, α-OR_y, where R_yis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, α-NO₂, spiroepoxy, or C(O)R_x, where R_xis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl. In a preferred embodiment, R₁is H.

As generally defined above, R₂is H, ═O, ═CHCN, ═CHCO₂R_w, where R_wis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, α-CN, α-OH, α-OR_v, where R_vis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, α-NO₂, spiroepoxy, or C(O)R_u, where R_uis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl. In a preferred embodiment, R₂is H. In another preferred embodiment, R₂is ═O.

As generally defined above, R₃is H, ═O, ═CHCN, ═CHCO₂R_t, where R_tis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, α-CN, α-OH, α-OR_s, where R_sis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, α-NO₂, spiroepoxy, or C(O)R_r, where R_ris optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl. In certain embodiments, R₃is ═O. In other certain embodiments, R₃is spiroepoxy. In yet other certain embodiments, R₃is α-CN. In still other certain embodiments, R₃is α-C(O)CH₃. In other certain embodiments, R₃is H.

As generally defined above, R₆is H.

As generally defined above, R₉is H, optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl. In certain embodiments, the optionally substituted aryl is optionally substituted phenyl. In other certain embodiments, the optionally substituted alkyl is optionally substituted alkyl aryl, such as alkyl benzyl. In a preferred embodiment, R₉is H. R₉is in the alpha configuration.

As generally defined above, R₁₂is H, N(CH₃)₂, N(CH₂CH₃)₂, optionally substituted morpholinyl, or OR_h, where R_his optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, optionally substituted C₂-C₄alkynyl, or optionally substituted aryl. In certain embodiments, the optionally substituted aryl is optionally substituted phenyl or naphthyl. In a preferred embodiment, R₁₂is H. R₁₂is in the alpha configuration.

In one embodiment, the C_4a—H is in the alpha configuration. In another embodiment, the C_4a—H is in the beta configuration. In another embodiment, the C_10a—H is in the beta configuration.

In certain embodiments, a double bond is present between C₁-C₂. In other certain embodiments, a double bond is present between C₈-C₉. When a double bond is present between C₈-C₉, R₃is other than ═O, ═CHCN or ═CHCO₂R_tand R₂is other than ═, ═CHCN or ═CHCO₂R_w. In other certain embodiments, a double bond is present between C₉-C₁₀. When a double bond is present between C₉-C₁₀, R₂is other than ═O, ═CHCN or ═CHCO₂R_wand R₁is other than ═O, ═CHCN or ═CHCO₂R_z.

For example, in various embodiments, compounds of the present disclosure have the formula of (II-a):

embedded image

wherein:

As generally defined above in Formula (II-a), R₂is H, ═O, ═CHCN, ═CHCO₂R_w, where R_wis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, α-CN, α-OH, α-OR_v, where R_vis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, α-NO₂, spiroepoxy, or C(O)R_u, where R_uis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl. In a preferred embodiment, R₂is H. In another preferred embodiment, R₂is ═O.

As generally defined above in Formula (II-a), R₃is H, ═O, ═CHCN, ═CHCO₂R_t, where R_tis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, α-CN, α-OH, α-OR_s, where R_sis optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl, α-NO₂, spiroepoxy, or C(O)R_r, where R_ris optionally substituted C₁-C₄alkyl, optionally substituted C₂-C₄alkenyl, or optionally substituted C₂-C₄alkynyl. In certain embodiments, R₃is ═O. In other certain embodiments, R₃is spiroepoxy. In yet other certain embodiments, R₃is α-CN. In still other certain embodiments, R₃is C(O)CH₃. In other certain embodiments, R₃is H.

Accordingly, as noted, the cyclopenta[b]phenanthrenes of Formulas (II) and (II-a) may encompass a number of various structures in accordance with the present disclosure, including all of the various combinations and permutations (i.e., combinations of substituent options, locations and stereochemical configurations) possible here.

Exemplary compounds of Formula (II) include, but are not limited to:

embedded image

and pharmaceutically acceptable salts thereof.

In this regard it is to be noted that the structures provided above are of various exemplary embodiments. As such, they should not be viewed in a limiting sense.

2. METHODS OF PREPARATION AND PHARMACEUTICAL COMPOSITIONS

It is to be noted that the compounds or cyclopenta[b]phenanthrenes of the present disclosure, may in various embodiments be prepared or used in accordance with means generally known in the art. For example, in certain embodiments, the cyclopenta[b]phenanthrenes of the present disclosure may be prepared or used in a pharmaceutically acceptable salt form. Suitable salt forms include, for example, citrate or chloride salt forms.

In various embodiments of the present disclosure, a pharmaceutical composition is disclosed that may comprise a cyclopenta[b]phenanthrene or a combination of two or more thereof in accordance with the formulas of the present disclosure. The compounds or cyclopenta[b]phenanthrenes of the present disclosure, as well as the various salt forms and other pharmaceutically acceptable forms, e.g., solvates and/or hydrates of compounds described herein, and pharmaceutical compositions containing them, may in general be prepared using methods and techniques known in the art, and/or as described in the Examples provided herein.

Without wishing to be bound by any particular theory, the compounds or cyclopenta[b]phenanthrenes of the present disclosure are useful for potentiating GABA at GABA_Areceptors thereby inducing anesthesia or treating disorders related to GABA function (e.g., insomnia, mood disorders, Fragile X syndrome, convulsive disorders, anxiety disorders, or symptoms of ethanol withdrawal) in a subject, e.g., a human subject, and are preferably administered in the form of a pharmaceutical composition comprising an effective amount of a compound of the instant disclosure and optionally a pharmaceutically or pharmacologically acceptable carrier.

In one aspect, provided is a method of inducing anesthesia in a subject in need thereof, the method comprising administering to the subject a therapeutically effective amount of one or more of the above-noted cyclopenta[b]phenanthrenes or pharmaceutically acceptable salts thereof, or a pharmaceutical composition thereof.

In another aspect, provided is a method of treating disorders related to GABA function in a subject in need thereof, the method comprising administering to the subject a therapeutically effective amount of one or more of the above-noted cyclopenta[b]phenanthrenes or pharmaceutically acceptable salts thereof, or a pharmaceutical composition thereof. In certain embodiments, the disorder is selected from the group consisting of insomnia, mood disorders, convulsive disorders, Fragile X syndrome, anxiety, or symptoms of ethanol withdrawal.

In one embodiment of the present disclosure, a therapeutically effective amount of compound is from about 5 mg/kg to about 20 mg/kg, about 5 mg/kg to about 18 mg/kg, about 5 mg/kg to about 16 mg/kg, about 5 mg/kg to about 14 mg/kg, about 5 mg/kg to about 12 mg/kg, about 5 mg/kg to about 10 mg/kg, about 6 mg/kg to about 10 mg/kg, about 6 mg/kg to about 9 mg/kg, about 7 mg/kg to about 9 mg/kg, or about 8 mg/kg to about 16 mg/kg. In certain embodiments, a therapeutically effective amount of the compound is about 8 mg/kg. It will be appreciated that dose ranges as described herein provide guidance for the administration of provided pharmaceutical compositions to an adult. The amount to be administered to, for example, a child or an adolescent can be determined by a medical practitioner or person skilled in the art and can be lower or the same as that administered to an adult.

The exact amount of a compound required to achieve an effective amount will vary from subject to subject, depending, for example, on species, age, and general condition of a subject, identity of the particular compound(s), mode of administration, and the like. The desired dosage can be delivered three times a day, two times a day, once a day, every other day, every third day, every week, every two weeks, every three weeks, or every four weeks. In certain embodiments, the desired dosage can be delivered using multiple administrations (e.g., two, three, four, five, six, seven, eight, nine, ten, eleven, twelve, thirteen, fourteen, or more administrations). In other certain embodiments, the compound may be administered via continuous intravenous (IV) infusion, such as used by those commonly skilled in the art of general anesthesia.

It will be also appreciated that a compound or composition, as described herein, can be administered in combination with one or more additional therapeutically active agents. The compounds or compositions can be administered in combination with additional therapeutically active agents that improve their bioavailability, reduce and/or modify their metabolism, inhibit their excretion, and/or modify their distribution within the body.

The compound or composition can be administered concurrently with, prior to, or subsequent to, one or more additional therapeutically active agents. In general, each agent will be administered at a dose and/or on a time schedule determined for that agent. It will further be appreciated that the additional therapeutically active agent utilized in this combination can be administered together in a single composition or administered separately in different compositions. The particular combination to employ in a regimen will take into account compatibility of the inventive compound with the additional therapeutically active agent and/or the desired therapeutic effect to be achieved. In general, it is expected that additional therapeutically active agents utilized in combination be utilized at levels that do not exceed the levels at which they are utilized individually. In some embodiments, the levels utilized in combination will be lower than those utilized individually. Exemplary therapeutically active agents include small organic molecules such as drug compounds (e.g., compounds approved by the US Food and Drug Administration as provided in the Code of Federal Regulations (CFR)), peptides, proteins, carbohydrates, monosaccharides, oligosaccharides, polysaccharides, nucleoproteins, mucoproteins, lipoproteins, synthetic polypeptides or proteins, small molecules linked to proteins, glycoproteins, steroids, nucleic acids, DNAs, RNAs, nucleotides, nucleosides, oligonucleotides, antisense oligonucleotides, lipids, hormones, vitamins and cells.

The pharmaceutical composition may also be in combination with at least one pharmacologically acceptable carrier. The carrier, also known in the art as an excipient, vehicle, auxiliary, adjuvant, or diluent, is any substance that is pharmaceutically inert, confers a suitable consistency or form to the composition, and does not diminish the therapeutic efficacy of the compounds. The carrier is “pharmaceutically or pharmacologically acceptable” if it does not produce an adverse, allergic, or other untoward reaction when administered to a mammal or human, as appropriate.

The pharmaceutical compositions containing the compounds or cyclopenta[b]phenanthrenes of the present disclosure may be formulated in any conventional manner. Proper formulation is dependent upon the route of administration chosen. The compositions of the disclosure can be formulated for any route of administration, so long as the target tissue is available via that route. Suitable routes of administration include, but are not limited to, oral, parenteral (e.g., intravenous, intraarterial, subcutaneous, rectal, subcutaneous, intramuscular, intraorbital, intracapsular, intraspinal, intraperitoneal, or intrasternal), topical (nasal, transdermal, intraocular), intravesical, intrathecal, enteral, pulmonary, intralymphatic, intracavital, vaginal, transurethral, intradermal, aural, intramammary, buccal, orthotopic, intratracheal, intralesional, percutaneous, endoscopical, transmucosal, sublingual, and intestinal administration. In certain embodiments, the route of administration is oral. In certain embodiments, the route of administration is parenteral. In certain embodiments, the route of administration is intravenous.

Pharmaceutically acceptable carriers for use in the compositions of the present disclosure are well known to those of ordinary skill in the art and are selected based upon a number of factors, including for example: the particular compound used, and its concentration, stability and intended bioavailability; the disease, disorder or condition being treated with the composition; the subject, its age, size and general condition; and/or the route of administration. Suitable carriers may be readily determined by one of ordinary skill in the art. (See, for example, J. G. Nairn, in: Remington's Pharmaceutical Science (A. Gennaro, ed.), Mack Publishing Co., Easton, Pa., (1985), pp. 1492-1517.)

The compositions may be formulated as tablets, dispersible powders, pills, capsules, gelcaps, caplets, gels, liposomes, granules, solutions, suspensions, emulsions, syrups, elixirs, troches, dragees, lozenges, or any other dosage form that can be administered orally. Techniques and compositions for making oral dosage forms useful in the present disclosure are described in the following exemplary references: 7 Modern Pharmaceutics, Chapters 9 and 10 (Banker & Rhodes, Editors, 1979); Lieberman et al., Pharmaceutical Dosage Forms: Tablets (1981); and, Ansel, Introduction to Pharmaceutical Dosage Forms 2nd Edition (1976).

The compositions of the present disclosure designed for oral administration comprise an effective amount of a compound of the disclosure in a pharmaceutically acceptable carrier. Suitable carriers for solid dosage forms include sugars, starches, and other conventional substances including lactose, talc, sucrose, gelatin, carboxymethylcellulose, agar, mannitol, sorbitol, calcium phosphate, calcium carbonate, sodium carbonate, kaolin, alginic acid, acacia, corn starch, potato starch, sodium saccharin, magnesium carbonate, tragacanth, microcrystalline cellulose, colloidal silicon dioxide, croscarmellose sodium, talc, magnesium stearate, and stearic acid. Further, such solid dosage forms may be uncoated or may be coated by known techniques (e.g., to delay disintegration and absorption).

The compounds and cyclopenta[b]phenanthrenes of the present disclosure may also be formulated for parenteral administration (e.g., formulated for injection via intravenous, intraarterial, subcutaneous, rectal, subcutaneous, intramuscular, intraorbital, intracapsular, intraspinal, intraperitoneal, or intrasternal routes). The compositions of the present disclosure for parenteral administration comprise an effective amount of the compound in a pharmaceutically acceptable carrier. Dosage forms suitable for parenteral administration include solutions, suspensions, dispersions, emulsions or any other dosage form that can be administered parenterally. Techniques and compositions for making parenteral dosage forms are known in the art. Typically formulations for parenteral administration are sterile or are sterilized before administration.

Suitable carriers used in formulating liquid dosage forms for oral or parenteral administration include nonaqueous, pharmaceutically-acceptable polar solvents such as oils, alcohols, amides, esters, ethers, ketones, hydrocarbons and mixtures thereof, as well as water, saline solutions, dextrose solutions (e.g., DW5), electrolyte solutions, or any other aqueous, pharmaceutically acceptable liquid.

Suitable nonaqueous, pharmaceutically-acceptable polar solvents include, but are not limited to, alcohols (e.g., α-glycerol formal, β-glycerol formal, 1,3-butyleneglycol, aliphatic or aromatic alcohols having 2-30 carbon atoms such as methanol, ethanol, propanol, isopropanol, butanol, t-butanol, hexanol, octanol, amylene hydrate, benzyl alcohol, glycerin (glycerol), glycol, hexylene glycol, tetrahydrofurfuryl alcohol, lauryl alcohol, cetyl alcohol, or stearyl alcohol, fatty acid esters of fatty alcohols such as polyalkylene glycols (e.g., polypropylene glycol, polyethylene glycol), sorbitan, sucrose and cholesterol); amides (e.g., dimethylacetamide (DMA), benzyl benzoate DMA, dimethylformamide, N-(β-hydroxyethyl)-lactamide, N,N-dimethylacetamide, 2-pyrrolidinone, 1-methyl-2-pyrrolidinone, or polyvinylpyrrolidone); esters (e.g., 1-methyl-2-pyrrolidinone, 2-pyrrolidinone, acetate esters such as monoacetin, diacetin, and triacetin, aliphatic or aromatic esters such as ethyl caprylate or octanoate, alkyl oleate, benzyl benzoate, benzyl acetate, dimethylsulfoxide (DMSO), esters of glycerin such as mono, di, or tri-glyceryl citrates or tartrates, ethyl benzoate, ethyl acetate, ethyl carbonate, ethyl lactate, ethyl oleate, fatty acid esters of sorbitan, fatty acid derived PEG esters, glyceryl monostearate, glyceride esters such as mono, di, or tri-glycerides, fatty acid esters such as isopropyl myristrate, fatty acid derived PEG esters such as PEG-hydroxyoleate and PEG-hydroxystearate, N-methylpyrrolidinone, pluronic 60, polyoxyethylene sorbitol oleic polyesters such as poly(ethoxylated)_30-60sorbitol poly(oleate)_2-4, poly(oxyethylene)_15-20monooleate, poly(oxyethylene)_15-20mono 12-hydroxystearate, and poly(oxyethylene)_15-20mono-ricinoleate, polyoxyethylene sorbitan esters (such as polyoxyethylene-sorbitan monooleate, polyoxyethylene-sorbitan monopalmitate, polyoxyethylene-sorbitan monolaurate, polyoxyethylene-sorbitan monostearate, and Polysorbate® 20, 40, 60 or 80 from ICI Americas, Wilmington, Del.), polyvinylpyrrolidone, alkyleneoxy modified fatty acid esters (such as polyoxyl 40 hydrogenated castor oil, cyclodextrins or modified cyclodextrins (e.g., beta-hydroxypropyl-cyclodextrin)), saccharide fatty acid esters (i.e., the condensation product of a monosaccharide (e.g., pentoses, such as ribose, ribulose, arabinose, xylose, lyxose and xylulose, hexoses such as glucose, fructose, galactose, mannose and sorbose, trioses, tetroses, heptoses, and octoses), disaccharide (e.g., sucrose, maltose, lactose and trehalose) or oligosaccharide or mixture thereof with a C₄-C₂₂fatty acid(s)(e.g., saturated fatty acids such as caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid and stearic acid, and unsaturated fatty acids such as palmitoleic acid, oleic acid, elaidic acid, erucic acid and linoleic acid)), or steroidal esters); alkyl, aryl, or cyclic ethers having 2-30 carbon atoms (e.g., diethyl ether, tetrahydrofuran, dimethyl isosorbide, diethylene glycol monoethyl ether); glycofurol (tetrahydrofurfuryl alcohol polyethylene glycol ether); ketones having 3-30 carbon atoms (e.g., acetone, methyl ethyl ketone, methyl isobutyl ketone); aliphatic, cycloaliphatic or aromatic hydrocarbons having 4-30 carbon atoms (e.g., benzene, cyclohexane, dichloromethane, dioxolanes, hexane, n-decane, n-dodecane, n-hexane, sulfolane, tetramethylenesulfone, tetramethylenesulfoxide, toluene, dimethylsulfoxide (DMSO), or tetramethylenesulfoxide); oils of mineral, vegetable, animal, essential or synthetic origin (e.g., mineral oils such as aliphatic or wax-based hydrocarbons, aromatic hydrocarbons, mixed aliphatic and aromatic based hydrocarbons, and refined paraffin oil, vegetable oils such as linseed, tung, safflower, soybean, castor, cottonseed, groundnut, rapeseed, coconut, palm, olive, corn, corn germ, sesame, persic and peanut oil and glycerides such as mono-, di- or triglycerides, animal oils such as fish, marine, sperm, cod-liver, haliver, squalene, squalane, and shark liver oil, oleic oils, and polyoxyethylated castor oil); alkyl or aryl halides having 1-30 carbon atoms and optionally more than one halogen substituent; methylene chloride; monoethanolamine; petroleum benzine; trolamine; omega-3 polyunsaturated fatty acids (e.g., alpha-linolenic acid, eicosapentaenoic acid, docosapentaenoic acid, or docosahexaenoic acid); polyglycol ester of 12-hydroxystearic acid and polyethylene glycol (Solutol® HS-15, from BASF, Ludwigshafen, Germany); polyoxyethylene glycerol; sodium laurate; sodium oleate; or sorbitan monooleate.

Other pharmaceutically acceptable solvents for use in the disclosure are well known to those of ordinary skill in the art, and are identified in The Handbook of Pharmaceutical Excipients, (American Pharmaceutical Association, Washington, D.C., and The Pharmaceutical Society of Great Britain, London, England, 1968), Modern Pharmaceutics, (G. Banker et al., eds., 3d ed.)(Marcel Dekker, Inc., New York, N.Y., 1995), The Pharmacological Basis of Therapeutics, (Goodman & Gilman, McGraw Hill Publishing), Pharmaceutical Dosage Forms, (H. Lieberman et al., eds.) (Marcel Dekker, Inc., New York, N.Y., 1980), Remington's Pharmaceutical Sciences (A. Gennaro, ed., 19th ed.)(Mack Publishing, Easton, Pa., 1995), The United States Pharmacopeia 24, The National Formulary 19, (National Publishing, Philadelphia, Pa., 2000), A. J. Spiegel et al., and Use of Nonaqueous Solvents in Parenteral Products, J. of Pharm. Sciences, Vol. 52, No. 10, pp. 917-927 (1963).

Preferred solvents include cyclodextrins or modified cyclodextrins (e.g., beta-hydroxypropyl-cyclodextrin) as well as oils rich in triglycerides, for example, safflower oil, soybean oil or mixtures thereof, and alkyleneoxy modified fatty acid esters such as polyoxyl 40 hydrogenated castor oil. Commercially available triglycerides include Intralipid® emulsified soybean oil (Kabi-Pharmacia Inc., Stockholm, Sweden), Nutralipid® emulsion (McGaw, Irvine, Calif.), Liposyn® II 20% emulsion (a 20% fat emulsion solution containing 100 mg safflower oil, 100 mg soybean oil, 12 mg egg phosphatides, and 25 mg glycerin per ml of solution; Abbott Laboratories, Chicago, Ill.), Liposyn® III 2% emulsion (a 2% fat emulsion solution containing 100 mg safflower oil, 100 mg soybean oil, 12 mg egg phosphatides, and 25 mg glycerin per ml of solution; Abbott Laboratories, Chicago, Ill.), natural or synthetic glycerol derivatives containing the docosahexaenoyl group at levels between 25% and 100% by weight based on the total fatty acid content (Dhasco® (from Martek Biosciences Corp., Columbia, Md.), DHA Maguro® (from Daito Enterprises, Los Angeles, Calif.), Soyacal®, and Travemulsion®.

Additional minor components can be included in the compositions of the disclosure for a variety of purposes well known in the pharmaceutical industry. These components will for the most part impart properties which enhance retention of the compound at the site of administration, protect the stability of the composition, control the pH, facilitate processing of the compound into pharmaceutical formulations, and the like. Preferably, each of these components is individually present in less than about 15 wt % of the total composition, more preferably less than about 5 wt %, and most preferably less than about 0.5 wt % of the total composition. Some components, such as fillers or diluents, can constitute up to 90 wt % of the total composition, as is well known in the formulation art. Such additives include cryoprotective agents for preventing reprecipitation, surface active, wetting or emulsifying agents (e.g., lecithin, polysorbate-80, Tween® 80, Pluronic 60, polyoxyethylene stearate), preservatives (e.g., ethyl-p-hydroxybenzoate), microbial preservatives (e.g., benzyl alcohol, phenol, m-cresol, chlorobutanol, sorbic acid, thimerosal and paraben), agents for adjusting pH or buffering agents (e.g., acids, bases, sodium acetate, sorbitan monolaurate), agents for adjusting osmolarity (e.g., glycerin), thickeners (e.g., aluminum monostearate, stearic acid, cetyl alcohol, stearyl alcohol, guar gum, methyl cellulose, hydroxypropylcellulose, tristearin, cetyl wax esters, polyethylene glycol), colorants, dyes, flow aids, non-volatile silicones (e.g., cyclomethicone), clays (e.g., bentonites), adhesives, bulking agents, flavorings, sweeteners, adsorbents, fillers (e.g., sugars such as lactose, sucrose, mannitol, or sorbitol, cellulose, or calcium phosphate), diluents (e.g., water, saline, electrolyte solutions), binders (e.g., starches such as maize starch, wheat starch, rice starch, or potato starch, gelatin, gum tragacanth, methyl cellulose, hydroxypropyl methylcellulose, sodium carboxymethyl cellulose, polyvinylpyrrolidone, sugars, polymers, acacia), disintegrating agents (e.g., starches such as maize starch, wheat starch, rice starch, potato starch, or carboxymethyl starch, cross-linked polyvinyl pyrrolidone, agar, alginic acid or a salt thereof such as sodium alginate, croscarmellose sodium or crospovidone), lubricants (e.g., silica, talc, stearic acid or salts thereof such as magnesium stearate, or polyethylene glycol), coating agents (e.g., concentrated sugar solutions including gum arabic, talc, polyvinyl pyrrolidone, carbopol gel, polyethylene glycol, or titanium dioxide), and antioxidants (e.g., sodium metabisulfite, sodium bisulfite, sodium sulfite, dextrose, phenols, and thiophenols).

Dosage from administration by these routes may be continuous or intermittent, depending, for example, upon the patient's physiological condition, whether the purpose of the administration is therapeutic or prophylactic, and other factors known to and assessable by a skilled practitioner.

Those with ordinary skill in administering anesthetics can readily determine dosage and regimens for the administration of the pharmaceutical compositions of the disclosure or titrating to an effective dosage for use in treating insomnia, mood disorders, convulsive disorders, anxiety or symptoms of ethanol withdrawal. It is understood that the dosage of the compounds will be dependent upon the age, sex, health, and weight of the recipient, kind of concurrent treatment, if any, frequency of treatment, and the nature of the effect desired. For any mode of administration, the actual amount of compound delivered, as well as the dosing schedule necessary to achieve the advantageous effects described herein, will also depend, in part, on such factors as the bioavailability of the compound, the disorder being treated, the desired therapeutic dose, and other factors that will be apparent to those of skill in the art. The dose administered to an animal, particularly a human, in the context of the present disclosure should be sufficient to affect the desired therapeutic response in the animal over a reasonable period of time. Preferably, an effective amount of the compound, whether administered orally or by another route, is any amount that would result in a desired therapeutic response when administered by that route. The dosage may vary depending on the dosing schedule, which can be adjusted as necessary to achieve the desired therapeutic effect. The most preferred dosage will be tailored to the individual subject, as is understood and determinable by one of ordinary skill in the art without undue experimentation.

In one embodiment, solutions for oral administration are prepared by dissolving the compound in any pharmaceutically acceptable solvent capable of dissolving a compound (e.g., ethanol or methylene chloride) to form a solution. An appropriate volume of a carrier which is a solution, such as beta-hydroxypropyl-cyclodextrin, is added to the solution while stirring to form a pharmaceutically acceptable solution for oral administration to a patient. If desired, such solutions can be formulated to contain a minimal amount of, or to be free of, ethanol, which is known in the art to cause adverse physiological effects when administered at certain concentrations in oral formulations.

In another embodiment, powders or tablets for oral administration are prepared by dissolving a compound in any pharmaceutically acceptable solvent capable of dissolving the compound (e.g., ethanol or methylene chloride) to form a solution. The solvent can optionally be capable of evaporating when the solution is dried under vacuum. An additional carrier can be added to the solution prior to drying, such as beta-hydroxypropyl-cyclodextrin. The resulting solution is dried under vacuum to form a glass. The glass is then mixed with a binder to form a powder. The powder can be mixed with fillers or other conventional tabletting agents and processed to form a tablet for oral administration to a patient. The powder can also be added to any liquid carrier as described above to form a solution, emulsion, suspension or the like for oral administration.

Emulsions for parenteral administration can be prepared by dissolving a compound in any pharmaceutically acceptable solvent capable of dissolving the compound (e.g., ethanol or methylene chloride) to form a solution. An appropriate volume of a carrier which is an emulsion, such as Liposyn® II or Liposyn® III emulsions, is added to the solution while stirring to form a pharmaceutically acceptable emulsion for parenteral administration to a patient.

Solutions for parenteral administration can be prepared by dissolving a compound in any pharmaceutically acceptable solvent capable of dissolving the compound (e.g., ethanol or methylene chloride) to form a solution. An appropriate volume of a carrier which is a solution, such as beta-hydroxypropyl-cyclodextrin, is added to the solution while stirring to form a pharmaceutically acceptable solution for parenteral administration to a patient.

If desired, the emulsions or solutions described above for oral or parenteral administration can be packaged in IV bags, vials or other conventional containers in concentrated form and diluted with any pharmaceutically acceptable liquid, such as saline, to form an acceptable concentration prior to use as is known in the art.

Still further encompassed by the disclosure are kits (e.g., pharmaceutical packs). The kits provided may comprise a compound as described herein and a container (e.g., a vial, ampule, bottle, syringe, and/or dispenser package, or other suitable container). In some embodiments, provided kits may optionally further include a second container comprising a pharmaceutical carrier for dilution or suspension of the pharmaceutical composition or compound. In some embodiments, the pharmaceutical composition or compound provided in the container and the second container are combined to form one unit dosage form.

Optionally, instructions for use are additionally provided in such kits of the disclosure. Such instructions may provide, generally, for example, instructions for dosage and administration. In other embodiments, instructions may further provide additional detail relating to specialized instructions for particular containers and/or systems for administration. Still further, instructions may provide specialized instructions for use in conjunction and/or in combination with an additional therapeutic agent.

3. DEFINITIONS

The term “steroid” as used herein describes an organic compound containing in its chemical nucleus the cyclopenta[b]phenanthrene ring system.

As used herein, the terms “alpha” and “beta” are used to describe the absolute configuration and orientation of the structure so as to define the plane and which way up the molecule is represented. The term “alpha” refers to substituents below the plane and is shown by a broken line. The term “beta” refers to substituents above the plane and is shown by a solid, bolded line.

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 humans and lower animals 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., describe pharmaceutically acceptable salts in detail in J. Pharmaceutical Sciences, 1977, 66, 1-19. Pharmaceutically acceptable salts of the compounds of this disclosure 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, 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. Salts derived from appropriate bases include alkali metal, alkaline earth metal, ammonium and N⁺(C_1-4alkyl)₄salts. Representative alkali or alkaline earth metal salts include sodium, lithium, potassium, calcium, magnesium, 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.

As used herein, a “subject” to which administration is contemplated includes, but is not limited to, mammals, e.g., humans (i.e., a male or female of any age group, e.g., a pediatric subject (e.g., child, adolescent) or adult subject (e.g., young adult, middle-aged adult or senior adult)), other primates (e.g., cynomolgus monkeys, rhesus monkeys) and commercially relevant mammals such as cattle, pigs, horses, sheep, goats, cats, and/or dogs. In any aspect and/or embodiment of the disclosure, the subject is a human.

As used herein, a “therapeutically effective amount” “an amount sufficient” or “sufficient amount” of a compound means the level, amount or concentration of the compound required for a desired biological response, e.g., analgesia.

The term “saturated” as used herein describes the state in which all available valence bonds of an atom (especially carbon) are attached to other atoms.

The term “unsaturated” as used herein describes the state in which not all available valence bonds along the alkyl chain are satisfied; in such compounds the extra bonds usually form double or triple bonds (chiefly with carbon).

When a range of values is listed, it is intended to encompass each value and subrange within the range. For example “C_1-4alkyl” is intended to encompass, C₁, C₂, C₃, C₄, C_1-3, C_1-2, C_2-4, C_2-3and C_3-4alkyl, while “C_1-22alkyl” is intended to encompass, for example, C₁, C₂, C₃, C₄, etc., as well as C_1-21, C_1-20, C_1-15, C_1-10, C_2-20, C_2-15, C_2-10, C_3-15, C_3-10, etc. alkyl.

As used herein, “alkyl” refers to a radical of a straight-chain or branched saturated hydrocarbon group having from, in some embodiments, 1 to 4 carbon atoms (“C_1-4alkyl”), and in other embodiments 1 to 22 carbon atoms (“C_1-22alkyl”). In some embodiments, an alkyl group has 1 to 3 carbon atoms (“C_1-3alkyl”). In some embodiments, an alkyl group has 1 to 2 carbon atoms (“C_1-2alkyl”). In some embodiments, an alkyl group has 1 carbon atom (“C₁alkyl”). In some embodiments, an alkyl group has 2 to 4 carbon atom (“C_2-4alkyl”). In yet other embodiments, an alkyl group has 1 to 21 carbon atoms (“C_1-21alkyl”), 1 to 20 carbon atoms (“C_1-20alkyl”), 1 to 15 carbon atoms (“C_1-15alkyl”), 1 to 10 carbon atoms (“C_1-10alkyl”), etc. Examples of such alkyl groups include methyl (C₁), ethyl (C₂), n-propyl (C₃), isopropyl (C₃), n-butyl (C₄), tertbutyl (C₄), secbutyl (C₄), isobutyl (C₄), pentyl (C₅), and the like.

As used herein, “alkenyl” or “alkene” refers to a radical of a straight-chain or branched hydrocarbon group having from, in some embodiments, 2 to 4 carbon atoms (“C_2-4alkenyl”), and in other embodiments 2 to 22 carbon atoms (“C_2-22alkenyl”), and one or more carbon-carbon double bonds. In some embodiments, an alkenyl group has 2 to 3 carbon atoms (“C_2-3alkenyl”). In some embodiments, an alkenyl group has 2 carbon atoms (“C₂alkenyl”). In yet other embodiments, an alkenyl group has 2 to 21 carbon atoms (“C_2-21alkenyl”), 2 to 20 carbon atoms (“C_2-20alkenyl”), 2 to 15 carbon atoms (“C_2-15alkenyl”), 2 to 10 carbon atoms (“C_2-10alkyl”), etc. 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 such alkenyl groups include ethenyl (C₂), 1-propenyl (C₃), 2-propenyl (C₃), 1-butenyl (C₄), 2-butenyl (C₄), butadienyl (C₄), 1-pentenyl (C₅), 2-pentenyl (C₅), and the like.

As used herein, “alkynyl” or “alkyne” refers to a radical of a straight-chain or branched hydrocarbon group having from 2 to 4 carbon atoms and one or more carbon-carbon triple bonds (“C_2-10alkynyl”). In some embodiments, an alkynyl group has 2 to 3 carbon atoms (“C_2-3alkynyl”). In some embodiments, an alkynyl group has 2 carbon atoms (“C₂alkynyl”). The one or more carbon-carbon triple bonds can be internal (such as in 2-butynyl) or terminal (such as in 1-butynyl). Examples of C_2-4alkynyl groups include, without limitation, ethynyl (C₂), 1-propynyl (C₃), 2-propynyl (C₃), 1-butynyl (C₄), 2-butynyl (C₄), and the like.

As used herein, “aryl” refers to a radical of a monocyclic or polycyclic (e.g., bicyclic or tricyclic) 4n+2 aromatic ring system (e.g., having 6, 10, or 14 electrons shared in a cyclic array) having 6-14 ring carbon atoms and zero heteroatoms provided in the aromatic ring system (“C_6-14aryl”). In some embodiments, an aryl group has 6 ring carbon atoms (“C₆aryl”; e.g., phenyl). In some embodiments, an aryl group has 10 ring carbon atoms (“C₁₀aryl”; e.g., naphthyl such as 1-naphthyl and 2-naphthyl). In some embodiments, an aryl group has 14 ring carbon atoms (“C_1-4aryl”; e.g., anthracyl).

As used herein, “alkoxy” refers to an alkyl, alkenyl, or alkynyl group, as defined herein, attached to an oxygen radical.

Alkyl, alkenyl, alkynyl, and aryl groups, as defined herein, are substituted or unsubstituted, also referred to herein as “optionally substituted”. In general, the term “substituted”, whether preceded by the term “optionally” or not, means that at least one hydrogen present on a group (e.g., a carbon or nitrogen atom) is replaced with a permissible substituent, e.g., a substituent which upon substitution 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 has 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. The term “substituted” is contemplated to include substitution with all permissible substituents of organic compounds, any of the substituents described herein that result in the formation of a stable compound. The present disclosure contemplates any and all such combinations in order to arrive at a stable compound. For purposes of this disclosure, heteroatoms such as nitrogen may have hydrogen substituents and/or any suitable substituent as described herein which satisfy the valencies of the heteroatoms and results in the formation of a stable moiety.

Exemplary substituents include groups that contain a heteroatom (such as nitrogen, oxygen, silicon, phosphorous, boron, sulfur, or a halogen atom), halogen (e.g., chlorine, bromine, fluorine, or iodine), a heterocycle, alkoxy, alkenoxy, alkynoxy, aryloxy, hydroxy, protected hydroxy, keto, acyl, acyloxy, nitro, amino, amido, nitro, cyano, thiol, ketals, acetals, esters and ethers.

EXAMPLES

The following Examples describe or illustrate various embodiments of the present disclosure. Other embodiments within the scope of the appended claims will be apparent to a skilled artisan considering the specification or practice of the disclosure as described herein. It is intended that the specification, together with the Examples, be considered exemplary only, with the scope and spirit of the disclosure being indicated by the claims, which follow the Example.

General Methods.

Solvents were either used as purchased or dried and purified by standard methodology. Extraction solvents were dried with anhydrous Na₂SO₄and after filtration, removed under reduced pressure on a rotary evaporator. Flash column chromatography was performed using silica gel (32-63 μm) purchased from Scientific Adsorbents (Atlanta, Ga.). Melting points were determined on a Kofler micro hot stage and are uncorrected. FT-IR spectra were recorded as films on a NaCl plate. NMR spectra were recorded in CDCl₃at ambient temperature at 300 or 400 MHz (¹H), 74 or 100 MHz (¹³C).

Compound Chemistry

In accordance with the following methods and Examples, the following compounds were prepared using methods known in the industry.

embedded image

In accordance with Scheme 1, the following compounds were prepared using methods generally known in the art and as outlined below.

embedded image

(3S,4aR,6aR,7aS,10aS,11aR,11bR)-Hexadecahydro-3-hydroxy-7a-methyl-8H-cyclopenta[b]phenanthren-8-one (1)

Compound 1 was prepared as described previously (see Scaglione, et al., “Neurosteroid Analogues. 14. Alternative Ring System Scaffolds: GABA Modulatory and Anesthetic Actions of Cyclopenta[b]phenanthrenes and Cyclopenta[b]anthracenes,” J. of Med. Chem., Vol. 51(5), pages 1309-1318 (2008)).

embedded image

(3S,4aR,6aR,7aS,10aS,11aR,11bR)-[Hexadecahydro-3-hydroxy-7a-methyl-cyclopenta[b]phenanthren-8(Z)-ylidene]-acetonitrile (2) and (3S,4aR,6aR,7aS,10aS,11aR,11bR)-[Hexadecahydro-3-hydroxy-7a-methyl-cyclopenta[b]phenanthren-8(E)-ylidene]-acetonitrile (3)

To a suspension of NaH (40 mg, 60%, 1.0 mmol) in THF (10 ml) was added diethyl cyanomethyl phosphonate (195 mg, 1.1 mmol) at room temperature. After 30 min, the ketone (100 mg, 0.36 mmol) in THF (10 mL) was added and the reaction was stirred for 14 h at room temperature. Aqueous NH₄Cl was added and the product extracted into EtOAc (50 mL×3). The combined extracts were dried, filtered, and concentrated. The crude ¹H NMR showed the E and Z olefins ratio is 1 to 1. The residue was purified by flash column chromatography (silica gel eluted with 20% EtOAc in hexanes) to afford compounds 2 and 3.

Compound 2 (35 mg) had: mp 208-209° C.; [α]_D²⁰ 6.4 (c 0.11, CHCl₃); ¹H NMR (CDCl₃) δ 5.09 (s, 1H), 4.00-4.10 (m, 1H), 0.94 (s, 3H); ¹³C NMR (CDCl₃) δ 179.4, 116.9, 88.1, 66.6, 49.4, 48.3, 47.4, 46.9, 42.6, 40.7, 38.7, 36.3, 34.2, 34.1, 33.0, 32.6, 28.2, 26.2, 23.5, 17.0; IR ν_max3503, 2216, 1636 cm⁻¹. Anal. Calcd for (C₂₀H₂₉NO): C, 80.22; H, 9.76; N, 4.68. Found: C, 80.33; H, 9.67; N, 4.53.

Compound 3 (20 mg) had: mp 135-137° C.; [α]_D²⁰ 31.1 (c 0.18, CHCl₃); ¹H NMR (CDCl₃) δ 5.00-5.05 (m, 1H), 4.05-4.10 (m, 1H), 2.68-2.57 (m, 2H), 0.83 (s, 3H); ¹³C NMR (CDCl₃) δ 181.2, 117.8, 87.9, 66.6, 48.4, 48.2, 47.3, 46.4, 42.8, 40.6, 38.4, 36.3, 34.3, 34.1, 33.0, 30.4, 28.2, 26.1, 23.5, 18.1; IR ν_max3451, 2216, 1637 cm⁻¹. Anal. Calcd for (C₂₀H₂₉NO): C, 80.22; H, 9.76; N, 4.68. Found: C, 80.20; H, 9.71; N, 4.61.

embedded image

In accordance with Scheme 2, the following compounds were prepared, using methods generally known in the art and as outlined below.

embedded image

(3S,4aR,6aR,7aS,10aS,11aR,11bR)-3-[[(1,1-Dimethylethyl)dimethylsilyl]oxy]-hexadecahydro-7a-methyl-8H-cyclopenta[b]phenanthren-8-one (4)

To a solution of compound 1 (100 mg, 0.36 mmol) in DMF (5 ml) was added tert-butyldimethylsilyl chloride (75 mg, 0.5 mmol) and imidazole (68 mg, 1.0 mmol) at room temperature. After 16 h, water was added and the product extracted into EtOAc (50 mL×2). The combined extracts were dried, filtered and removed. The residue was purified by flash column chromatography (silica gel eluted with 10% EtOAc in hexanes) to afford compound 4 (130 mg, 93%): ¹H NMR (CDCl₃) δ 3.95-4.00 (m, 1H), 0.86 (s, 9H), 0.00 (s, 6H); ¹³C NMR (CDCl₃) δ 221.1, 66.6, 48.4, 47.8, 47.3, 45.7, 41.3, 39.4, 38.1, 36.1, 35.7, 34.1, 33.6, 28.4, 25.8, 24.1, 23.4, 18.0, 13.5, −4.8, −4.9.

embedded image

(3S,4aR,6aR,7aS,10aS,11aR,11bR)-3-[[(1,1-Dimethylethyl)dimethylsilyl]oxy]-hexadecahydro-7a-methyl-8H-cyclopenta[b]phenanthren-8-one oxime (5)

To a solution of compound 4 (130 mg, 0.33 mmol) in pyridine (10 mL) was added hydroxylamine hydrochloride (140 mg, 2.0 mmol) at room temperature. After 14 h, water was added and the product extracted into EtOAc (50 mL×2). The combined extracts were dried, filtered and removed. The residue was purified by flash column chromatography (silica gel eluted with 10% EtOAc in hexanes) to afford compound 5 (105 mg, 82%): ¹H NMR (CDCl₃) δ 9.00 (s, br, 1H), 3.95-4.00 (m, 1H), 2.45-2.51 (m, 2H), 0.87 (s, 9H), 0.01 (s, 6H); ¹³C NMR (CDCl₃) δ 171.0, 66.7, 48.5, 48.1, 47.4, 44.0, 41.9, 41.4, 38.2, 36.2, 34.1, 33.7, 27.9, 25.8, 25.4, 25.0, 23.4, 18.1, 17.0, −4.96, −4.91.

embedded image

(3S,4aR,6aR,7aS,8S,10aS,11aR,11bR)-Hexadecahydro-7a-methyl-8-nitro-cyclopenta[b]phenanthren-3-ol (6)

To a solution of NBS (210 mg, 1.3 mmol) in dioxane (4 mL) was added aqueous KHCO₃(260 mg, 2.6 mmol, 4 mL) at room temperature. The mixture was stirred for 30 min at room temperature. Compound 5 (105 mg, 0.26 mmol) in dioxane (10 mL) was added. The reaction was stirred for 14 h at room temperature and then NaBH₄was added (200 mg in 5 portions). The reaction was stirred for 3 h at room temperature. 6 N HCl (10 mL) was added and stirring at room temperature continued for 1 h. The product was extracted into EtOAc (50 mL×2). The combined extracts were dried, filtered, and removed. The residue was purified by flash column chromatography (silica gel eluted with 20% EtOAc in hexanes) to afford compound 6 (62 mg, 56%): mp 157-159° C.; [α]_D²⁰+32.4 (c 0.21, CHCl₃); ¹H NMR (CDCl₃) δ 4.40 (t, J=8.2 Hz, 1H), 4.05-4.10 (m, 1H), 2.56-2.51 (m, 1H), 0.73 (s, 3H); ¹³C NMR (CDCl₃) δ 94.4, 66.3, 47.9, 47.2, 47.0, 45.8, 45.1, 40.4, 38.3, 36.1, 33.9, 33.8, 32.7, 28.4, 25.7, 24.6, 2.32, 12.1; IR ν_max3385, 2212, 1542 cm⁻¹. Anal. Calcd for (C₁₈H₂₉NO₃): C, 70.32; H, 9.51; N, 4.56. Found: C, 70.12; H, 9.32; N, 4.33.

embedded image

In accordance with Scheme 3, the following compounds were prepared, using methods generally known in the art and as outlined below.

embedded image

(3S,4aR,6aR,7aS,10aS,11aR,11bR)-Hexadecahydro-3-(methoxymethoxy)-7a-methyl-8H-cyclopenta[b]phenanthren-8-one (7)

To a solution of compound 1 (215 mg, 0.77 mmol) in dried dichloromethane (15 mL) was added DIPEA (260 mg, 2.0 mmol), chloromethyl methyl ether (242 mg, 3.0 mmol), and DMAP (10 mg) at room temperature. After 16 h, water was added water and the product extracted into dichloromethane (100 mL×2). The combined extracts were dried, filtered, and removed. The residue was purified by flash column chromatography (silica gel eluted with 10% EtOAc in hexanes) to afford compound 7 (235 mg, 94%): ¹H NMR (CDCl3) δ 4.63 (s, 2H), 3.86-3.84 (m, 1H), 3.34 (s, 3H), 0.84 (s, 3H); ¹³C NMR (CDCl3) δ 221.0, 94.5, 71.3, 55.1, 48.3, 47.8, 46.9, 45.7, 39.3, 38.2, 38.0, 36.7, 35.6, 33.9, 30.2, 28.4, 24.0, 23.9, 13.5.

embedded image

(3S,4aR,6aR,7aS,10aR,11aR,11bR)-3-(Methoxymethoxy)-7a-methyl-2,3,4,4a,5,6,6a,7,7a,10,10a,11,11a,11b-tetradecahydro-1H-cyclopenta[b]phenanthrene-8-carbonitrile (8)

To a solution of compound 7 (235 mg, 0.73 mmol) in THF (15 mL) was added potassium bis(trimethylsilyl) amide (0.5 M in toluene, 2.0 mL, 1.0 mmol) at −78° C. After 30 min, N-phenyltrifluoromethanesulfonimide (357 mg, 1.0 mmol) in 5 mL of THF was added at 78° C. After 2 h, water was added and the product was extracted into EtOAc (50 mL×3). The combined extracts were dried, filtered, and concentrated. The residue was partially purified by flash column chromatography (silica gel eluted with 10% EtOAc in hexanes) to afford an intermediate enol triflate (310 mg containing an aromatic impurity from the sulfonamide reagent) which was immediately used.

To the enol triflate in a 50 mL round flask was added sodium cyanide (150 mg, 3.0 mmol), copper (I) iodide (60 mg, 0.3 mmol) and Pd(PPh₃)₄(30 mg) at room temperature. Acetonitrile (15 mL) was added and the mixture was refluxed for 1 h. Aqueous NH₄Cl was added and the product extracted into EtOAc (50 mL×3). The combined extracts were dried, filtered, and concentrated. The residue was purified by flash column chromatography (silica gel eluted with 10% EtOAc in hexanes) to afford compound 8 (180 mg, 85%): ¹H NMR (CDCl₃) δ 6.63-6.61 (m, 1H), 4.65 (s, 2H), 3.87-3.85 (m, 1H), 3.36 (s, 3H), 0.92 (s, 3H); ¹³C NMR (CDCl₃) δ 147.5, 127.4, 115.9, 94.5, 71.3, 55.0, 50.4, 48.9, 48.1, 46.9, 41.7, 38.5, 38.1, 36.7, 34.8, 34.0, 33.9, 30.2, 26.6, 23.8, 16.5.

embedded image

(3S,4aR,6aR,7aS,8S,10aS,11aR,11bR)-Hexadecahydro-3-(methoxymethoxy)-7a-methyl-cyclopenta[b]phenanthrene-8-carbonitrile (9)

To a solution of compound 8 (180 mg, 0.6 mmol) in EtOAc (40 mL) was added Pd/C (100 mg) and hydrogenation was carried out under 7 atm H₂at room temperature for 3 h. The reaction was filtered through Celite® 545 which was washed with EtOAc (100 mL). Solvents were removed and the residue was purified by flash column chromatography (silica gel eluted with 10% EtOAc in hexanes) to afford compound 9 (172 mg, 94%): ¹H NMR (CDCl₃) δ 4.58 (s, 2H), 3.82-3.79 (m, 1H), 3.29 (s, 3H), 0.84 (s, 3H); ¹³C NMR (CDCl₃) δ 121.4, 94.5, 71.8, 54.9, 48.4, 47.9, 46.7, 44.9, 44.4, 39.7, 38.1, 37.9, 36.6, 33.8, 33.7, 30.0, 28.3, 26.3, 26.2, 23.7, 14.2.

embedded image

(3S,4aR,6aR,7aS,8S,10aS,11aR,11bR)-Hexadecahydro-3-hydroxy-7a-methyl-cyclopenta[b]phenanthrene-8-carbonitrile (10)

To compound 9 (165 mg, 0.5 mmol) in methanol (9 mL) and dichloromethane (3 mL) was added 6 N HCl (10 ml) at room temperature. After 14 h, the product was extracted into EtOAc (50 mL×2). The combined extracts were dried, filtered, and concentrated. The residue was purified by flash column chromatography (silica gel eluted with 25% EtOAc in hexanes) to afford compound 10 (135 mg, 94%): mp 162-164° C.; [α]_D²⁰+33.9 (c 0.31, CHCl₃); ¹H NMR (CDCl₃) δ 4.06 (s, br, 1H), 0.86 (s, 3H); ¹³C NMR (CDCl₃) δ 121.3, 66.1, 48.3, 47.9, 46.9, 44.9, 44.2, 40.2, 39.8, 38.1, 36.0, 33.8, 33.7, 32.6, 28.4, 26.3 (2C), 23.1, 14.2; IR ν_max3456, 2235, 1447 cm⁻¹. Anal. Calcd for (C₁₉H₂₉NO): C, 79.39; H, 10.17; N, 4.87. Found: C, 79.60; H, 10.26; N, 4.92.

embedded image

1-[(3S,4aR,6aR,7aS,8S,10aS,11aR,11bR)-Hexadecahydro-3-hydroxy-7a-methyl-cyclopenta[b]phenanthren-8-yl]-ethanone (11)

To a solution of compound 11 (110 mg, 0.4 mmol) in THF (10 mL) was added methyl magnesiumbromide (3.0 M, 2 mL, 6.0 mmol) at room temperature. The reaction was refluxed for 16 h and then cooled to room temperature. 6 N HCl was added and the product was extracted into EtOAc (50 mL×3). The combined extracts were dried, filtered, and concentrated. ¹H NMR of the crude product (120 mg, 99%) showed the 8S and 8R diastereomers in the ratio of 8 to 1. The residue was purified by flash column chromatography (silica gel eluted with 20% EtOAc in hexanes) to afford compound 11 (35 mg): mp 131-133° C.; [α]_D²⁰+75.0 (c 0.12, CHCl₃); ¹H NMR (CDCl₃) δ 4.09-4.07 (m, 1H), 2.54 (t, J=8.8 Hz, 1H), 2.11 (s, 3H), 0.58 (s, 3H); ¹³C NMR (CDCl₃) δ 209.7, 66.4, 63.6, 50.7, 48.1, 47.2 (2×C), 44.1, 40.4, 38.4, 36.2, 34.3, 34.0, 32.8, 31.5, 28.4, 26.5, 23.2, 22.6, 13.3; IR ν_max3291, 1706 cm⁻¹. MS (FAB) for [C₂₀H₃₂O₂+Na]⁺: 327.2300. Found: 327.2300.

embedded image

In accordance with Scheme 4, the following compounds were prepared, using methods generally known in the art and as outlined below.

embedded image

(6aR,7aS,10aS,11aR,11bS)-6,6a,7,7a,9,10,10a,11,11a,11b-Decahydro-7a-methyl-1H-cyclopenta[b]phenanthrene-3,8(2H,5H)-dione (12)

Compound 12 was prepared as reported previously (see Qian & Covey, “The efficient and enantiospecific total synthesis of cyclopenta[b]phenanthrenes structurally related to neurosteroids,” Adv. Syn. & Cata., Vol. 352 (11-12), pages 2057-2061 (2010)).

embedded image

(4aS,6aR,7aS,10aS,11aR,11bR)-Dodecahydro-7a-methyl-1H-cyclopenta[b]phenanthrene-3,8(2H,4H)-dione (13)

To a solution compound 12 (150 mg, 0.54 mmol) in pyridine (30 mL) was added Pd/C (50 mg) at room temperature. A hydrogenation was carried out under 7 atm H2 for 2 h at room temperature. The reaction was filtered through Celite® 545 which was washed with EtOAc (100 mL). Solvents were removed under reduced pressure and ¹³C NMR of the crude product (145 mg) showed the 4aS to 4aR diastereomer ratio to be 2:1: 1H NMR (CDCl3) δ 0.84 (s, 3H); 13C NMR (CDCl3) 4aS diastereomer δ 220.4, 212.2, 47.8, 45.6, 42.7, 39.9, 38.9, 38.6, 38.2, 38.1, 36.3, 35.4, 30.7, 28.5, 28.4, 27.1, 23.9, 13.5.

embedded image

(3S,4aS,6aR,7aS,10aS,11aR,11bR)-Hexadecahydro-3-hydroxy-7a-methyl-8H-cyclopenta[b]phenanthren-8-one (14)

To a solution of compound 13 (145 mg containing the unseparated 4aR diastereomer, 0.54 mmol) in THF (10 mL) was slowly added lithium tri-t-butyloxyaluminohydride at −40° C. After 2 h, 6 N HCl was added at −40° C. and the reaction was warmed to room temperature for 30 min. The product was extracted into EtOAc (50 mL×2). The combined extracts were dried, filtered, and removed. The residue was purified by flash column chromatography (silica gel eluted with 25% EtOAc in hexanes) and the product from the 4aR diastereomer separated to afford pure compound 14 (82 mg, 56%): mp 175-177° C.; [α]_D²⁰+34.5 (c 0.22, CHCl₃); ¹H NMR (CDCl₃) δ 3.58-3.49 (m, 1H), 0.76 (s, 3H); ¹³C NMR (CDCl₃) δ 221.1, 71.4, 47.9, 45.7, 40.1, 39.2, 38.8, 38.5, 36.2, 35.6, 35.5, 31.7, 29.6, 29.3, 28.4, 25.5, 24.1, 13.5; IR ν_max3398, 1736 cm⁻¹. Anal. Calcd for (C₁₈H₂₈O₂): C, 78.21; H, 10.21. Found: C, 78.12; H, 10.40.

embedded image

(2′S,3S,4aS,6aR,7aS,10aS,11aR,11bR)-Hexadecahydro-7a-methyl-spiro[8H-cyclopenta[b]phenanthrene-8,2′-oxiran]-3-ol (15)

To a solution of compound 14 (60 mg, 0.23 mmol) in DMSO (3 mL) was added trimethylsulfonium iodide (204 mg, 1.0 mmol) and potassium tert-butoxide (112 mg, 1.0 mmol) at room temperature. After 3 h, water (20 mL) was added and the product extracted into EtOAc (50 mL×3). The combined extracts were dried, filtered and concentrated. The residue was purified by flash column chromatography (silica gel eluted with 30% EtOAc in hexanes) to give compound 15 (48 mg, 72%) as a white solid: 160-162° C.; [α]_D²⁰ 16.5 (c 0.20, CHCl₃); ¹H NMR (CDCl₃) δ 3.64-3.50 (m, 1H), 2.91 (d, J=4.9 Hz, 1H), 2.62 (d, J=4.9 Hz, 1H), 0.87 (s, 3H); ¹³C NMR (CDCl₃) δ 71.7, 70.6, 53.6, 47.1, 42.0, 40.3, 40.2, 38.9, 38.4, 36.3, 35.7, 31.8, 29.8, 29.6, 28.9 (2×C), 25.8, 25.5, 14.4; IR ν_max3387, 1733 cm⁻¹. Anal. Calcd for (C₁₉H₃₀O₂): C, 78.57; H, 10.41. Found: C, 78.36; H, 10.50.

embedded image

In accordance with Scheme 5, the following compounds were prepared, using methods generally known in the art and as outlined below.

embedded image

(1S,3aS,8aR,9aS)-5-(3-Buten-1-yl)-1-(1,1-dimethylethoxy)-1,2,3,3a,4,7,8,8a,9,9a-decahydro-9a-methyl-6H-benz[t]inden-6-one (16)

Compound 16 was prepared as described previously (see Qian & Covey, “The efficient and enantiospecific total synthesis of cyclopenta[b]phenanthrenes structurally related to neurosteroids,” Adv. Syn. & Cata., Vol. 352 (11-12), pages 2057-2061 (2010)).

embedded image

(1S,3aS,4aR,5S,8aR,9aS)-5-(3-Buten-1-yl)-5,9a-dimethyl-1-(1,1-dimethylethoxy)-dodecahydro-6H-benz[t]inden-6-one (17)

A three-neck flask equipped with a dry ice condenser was cooled to −78° C., and anhydrous ammonia (100 mL) was condensed into the flask. Lithium (0.57 g, 82 mmol, 10 equiv) was added, and the resulting blue solution was stirred for 0.5 h. To this was added a solution of compound 16 (2.0 g, 6.1 mmol) in dry THF (50 mL). After 3 h, iodomethane (4.26 g, 30 mmol) was added, and the reaction mixture was allowed to warm to room temperature overnight and aqueous NH₄Cl was added. The product was extracted into EtOAc (100 mL×3), and the combined extracts were washed with brine, dried and the solvent evaporated. Column chromatography (silica gel eluted with 10% EtOAc in hexanes) gave compound 17 (1.40 g, 67%) as a colorless oil: ¹H NMR (CDCl₃) δ 5.81-5.77 (m, 1H), 4.96-4.88 (m, 2H), 3.39 (t, J=7.4 Hz, 1H), 1.11 (s, 9H), 1.06 (s, 3H), 0.75 (s, 3H); ¹³C NMR (CDCl₃) δ 214.9, 139.2, 113.9, 80.4, 72.1, 51.1, 47.5, 44.8, 44.5, 42.6, 38.4, 33.7, 33.5, 31.2, 28.7, 28.6, 25.8, 24.7, 21.1, 11.7.

embedded image

(1S,3aS,4aR,5S,8aR,9aS)-5,9a-Dimethyl-1-(1,1-dimethylethoxy)dodecahydro-5-(3-oxobutyl)-6H-benz[t]inden-6-one (18)

A suspension of PdCl₂and CuCl were stirred in DMF/H₂O (15 mL, v/v=9/1) at room temperature under O₂for 1 h. Compound 17 (1.40 g, 4.04 mmol) in DMF/H₂O (10 mL, v/v=9/1) was added by syringe. The reaction mixture was stirred and monitored by TLC. After 20 h, the starting material was completely consumed. Water (40 mL) was added and the product extracted into EtOAc (50 mL×3). The combined extracts were dried, filtered and concentrated. The residue was purified by flash column chromatography (silica gel eluted with 10% EtOAc in hexanes) to give compound 18 (933 mg, 64%): ¹H NMR (CDCl₃) δ 3.39 (t, J=7.8 Hz, 1H), 2.56-2.22 (m, 4H), 2.15 (s, 3H), 1.12 (s, 9H), 1.10 (s, 3H), 0.76 (s, 3H); ¹³C NMR (CDCl₃) δ 215.3, 209.3, 80.4, 72.2, 50.6, 48.5, 44.7, 44.6, 42.6, 38.9, 38.4, 33.8, 31.4, 31.2, 29.9, 28.7, 28.2, 25.8, 24.7, 20.6, 11.7; IR ν_max2971, 1706, 1360 cm⁻¹.

embedded image

(6aR,7aS,8S,10aS,11aR,11bS)-1,2,5,6,6a,7,7a,8,9,10,10a,11,11a,11b-Tetradecahydro-11b,7a-Dimethyl-8-hydroxy-3H-cyclopenta[b]phenanthren-3-one (19)

To a solution of compound 18 (930 g, 2.58 mmol) in MeOH (20 mL) was added 3 N HCl (20 mL) at room temperature. The reaction was stirred and refluxed for 16 h. After cooling to room temperature, the product was extracted into EtOAc (50 mL×3). The combined extracts were dried, filtered, and concentrated. The residue was purified by flash column chromatography (silica gel eluted with 20% EtOAc in hexanes) to give compound 19 (557 mg, 75%) as a white semisolid: [α]_D²⁵=75.2 (c 0.29, CHCl₃); ¹H NMR (CDCl₃) δ 5.70 (s, 1H), 3.65 (t, J=8.6 Hz, 1H), 1.16 (s, 3H), 0.75 (s, 3H); ¹³C NMR (CDCl₃) δ 199.7, 171.5, 123.8, 81.3, 54.0, 44.8, 44.5, 42.8, 38.8, 35.4, 34.6, 33.7, 33.2, 31.9, 30.3, 25.4, 24.3, 17.4, 11.1; IR ν_max3435, 1667 cm⁻¹.

embedded image

(4aR,6aR,7aS,8S,10aS,11aR,11bR)-Hexadecahydro-11b,7a-dimethyl-8-hydroxy-3H-cyclopenta[b]phenanthren-3-one (20)

A three-neck flask equipped with a dry ice condenser was cooled to −78° C. and anhydrous ammonia (100 mL) was condensed into the flask. Lithium (134 mg, 19 mmol, 10 equiv) was added, and the resulting blue solution was stirred for 0.5 h. To this was added a solution of compound 19 (550 g, 1.91 mmol) in dry THF (50 mL). After 3 h of stirring, solid NH₄Cl was added until the blue color disappeared, and the reaction mixture was allowed to warm to room temperature overnight and aqueous NH₄Cl was added. The product was extracted into EtOAc (100 mL×3), and the combined organic extracts were washed with brine, dried and the solvent evaporated. Column chromatography (silica gel eluted with 10% EtOAc in hexanes) gave compound (480 mg, 87%) as a colorless oil: ¹H NMR (CDCl₃) δ 3.63 (t, J=7.8 Hz, 1H), 0.98 (s, 3H), 0.72 (s, 3H); ¹³C NMR (CDCl₃) δ 212.0, 81.5, 54.0, 46.6, 45.0, 44.5, 43.0, 38.2, 37.9, 35.8, 34.6, 31.8, 30.3, 29.1, 25.5, 24.7, 11.4, 11.1; IR ν_max3416, 1709 cm⁻¹.

embedded image

(4aR,6aR,7aS,10aS,11aR,11bR)-Dodecahydro-7a,11b-dimethyl-1H-cyclopenta[b]phenanthrene-3,8(2H,4H)-dione (21)

Jones reagent was added to a solution of compound 20 (480 mg, 1.66 mmol) in acetone (40 mL) at 0° C. until a brown-yellowish color persisted. After 10 min, 2-propanol (1.0 mL) was added and then brine (50 mL) was added. The product was extracted into EtOAc (50 mL×3). The combined extracts were dried, filtered, and concentrated. The residue was purified by flash column chromatography (silica gel eluted with 20% EtOAc in hexanes) to give compound 21 (461 mg, 96%): ¹H NMR (CDCl₃) δ 1.02 (s, 3H), 0.87 (s, 3H); ¹³C NMR (CDCl₃) δ 220.1, 211.0, 48.2, 47.8, 47.6, 45.6, 45.4, 43.5, 40.9, 38.9, 37.6, 35.4, 34.0, 33.4, 29.9, 28.7, 23.8, 13.4; IR ν_max1734, 1714 cm⁻¹.

embedded image

(3S,4aR,6aR,7aS,10aS,11aR,11bR)-Hexadecahydro-7a,11b-dimethyl-3-hydroxy-8H-cyclopenta[b]phenanthren-8-one (22)

To a solution of compound 21 (460 mg, 1.6 mmoL) in THF (20 mL) was added K-selectride (2.0 mmol, 2.0 mL, 1.0 M) at −78° C. After 3 h, 10% aqueous NaOH (30 mL) and 30% H₂O₂(20 mL) were added at −78° C. The reaction was then warmed to room temperature for 1 h. The product was extracted into EtOAc (50 mL×3). The combined extracts were dried, filtered, and concentrated. The residue was purified by flash column chromatography (silica gel eluted with 30% EtOAc in hexanes) to give compound 22 (294 mg, 64%) as a white solid: mp 179-181° C., [α]_D²⁵+46.9 (c 0.16, CHCl₃); ¹H NMR (CDCl₃) δ 4.05 (s, br, 1H), 0.85 (s, 3H), 0.79 (s, 3H); ¹³C NMR (CDCl₃) δ 221.1, 66.4, 54.6, 47.8, 45.8, 39.8, 39.1, 36.4, 35.7, 34.8, 32.0, 31.8, 28.8, 28.7, 24.1, 24.0, 13.6, 11.2; IR ν_max3434, 1736 cm⁻¹. Anal. Calcd for (C₁₉H₃₀O₂): C, 78.57; H, 10.41. Found: C, 78.45; H, 10.28.

embedded image

In accordance with Scheme 6, the following compounds were prepared, using methods generally known in the art and as outlined below.

embedded image

(2′S,3S,4aR,6aR,7aS,10aS,11aR,11bR)-Hexadecahydro-7a,11b-dimethyl-spiro[8H-cyclopenta[b]phenanthrene-8,2′-oxiran]-3-ol (23)

To a solution of compound 22 (35 mg, 0.12 mmol) in DMSO (3 mL) was added trimethylsulfonium iodide (204 mg, 1.0 mmol) and potassium tert-butoxide (112 mg, 1.0 mmol) at room temperature. After 3 h, water (20 mL) was added and the product extracted into EtOAc (50 mL×3). The combined extracts were dried, filtered and concentrated. The residue was purified by flash column chromatography (silica gel eluted with 20% EtOAc in hexanes) to afford compound 23 (23 mg, 63%): mp 138-140° C.; [α]_D²⁰−16.7 (c 0.15, CHCl₃); ¹H NMR (CDCl₃) δ 4.06 (s, br, 1H), 2.90 (d, J=5.1 Hz, 1H), 2.61 (d, J=5.1 Hz, 1H), 0.86 (s, 3H), 0.79 (s, 3H); ¹³C NMR (CDCl₃) δ 70.5, 66.6, 54.6, 53.6, 47.1, 42.6, 40.2, 39.2, 36.4, 35.8, 35.1, 32.0, 31.8, 29.1, 28.9, 28.8, 25.9, 24.4, 14.4, 11.2; IR ν_max3435, 1007, 758 cm⁻¹. Anal. Calcd for (C₂₀H₃₂O₂): C, 78.90; H, 10.59. Found: C, 78.83; H, 10.77.

embedded image

(3S,4aR,6aR,7aS,10aS,11aR,11bR)-Hexadecahydro-7a,11b-dimethyl-3-(methoxymethoxy)-8H-cyclopenta[b]phenanthren-8-one (24)

To a solution of compound 22 (120 mg, 0.41 mmol) in dried dichloromethane (15 mL) was added DIPEA (130 mg, 1.0 mmol), chloromethyl methyl ether (121 mg, 1.5 mmol), and DMAP (10 mg) at room temperature. After 16 h, water was added and the product extracted into dichloromethane (100 mL×2). The combined extracts were dried, filtered, and removed. The residue was purified by flash column chromatography (silica gel eluted with 10% EtOAc in hexanes) to afford compound 24 (138 mg, 100%): ¹H NMR (CDCl₃) δ 4.60 (s, 2H), 3.79-3.78 (m, 1H), 3.31 (s, 3H), 0.80 (s, 3H), 0.76 (s, 3H); ¹³C NMR (CDCl₃) δ 220.9, 94.4, 71.5, 55.0, 54.5, 47.7, 45.8, 39.8, 39.6, 36.1, 35.6, 34.7, 33.4, 32.6, 31.7, 28.7, 26.2, 24.1, 23.9, 13.5, 11.3.

embedded image

1,1,1-Trifluoromethanesulfonic acid (3S,4aR,6aR,7aS,10aR,11aR,11bR)-7a,11b-Dimethyl-3-(Methoxymethoxy)-2,3,4,4a,5,6,6a,7,7a,10,10a,11,11a,11b-tetradecahydro-1H-cyclopenta[b]phenanthren-8-yl ester (25)

To a solution of compound 24 (136 mg, 0.4 mmol) in THF (15 mL) was added potassium bis(trimethylsilyl)amide (0.5 M in toluene, 2.0 mL, 1.0 mmol) at −78° C. After 30 min, N-phenyltrifluoromethanesulfonimide (357 mg, 1.0 mmol) in THF (5 mL) was added at −78° C. After 2 h at 78° C., water was added and the product extracted into EtOAc (50 mL×3). The combined extracts were dried, filtered, and concentrated. The residue was partially purified by flash column chromatography (silica gel eluted with 10% EtOAc in hexanes) to afford compound 25 (185 mg containing an aromatic impurity from the sulfonamide reagent) which was immediately converted to compound 26.

embedded image

(3S,4aR,6aR,7aS,10aR,11aR,11bR)-7a,11b-Dimethyl-3-(Methoxymethoxy)-2,3,4,4a,5,6,6a,7,7a,10,10a,11,11a,11b-tetradeca hydro-1H-cyclopenta[b]phenanthren-8-Carbonitrile (26)

To compound 26 (185 mg containing an aromatic impurity from the sulfonamide reagent) in a 50 mL round flask was added sodium cyanide (150 mg, 3.0 mmol), copper (I) iodide (60 mg, 0.3 mmol) and Pd(PPh₃)₄(30 mg) at room temperature. Acetonitrile (15 mL) was added and the reaction was refluxed for 1 h. Aqueous NH₄Cl was added and the product extracted into EtOAc (50 mL×3). The combined extracts were dried, filtered, and concentrated. The residue was partially purified by flash column chromatography (silica gel eluted with 10% EtOAc in hexanes) to afford compound 26 (130 mg containing an aromatic impurity from the sulfonamide reagent): ¹H NMR (CDCl₃) δ 6.56-6.55 (m, 1H), 4.59 (s, 2H), 3.77-3.76 (m, 1H), 3.30 (s, 3H), 0.84 (s, 3H), 0.74 (s, 3H); ¹³C NMR (CDCl₃) δ 147.8, 127.3, 116.0, 94.4, 71.6, 55.1, 55.0, 50.0, 48.2, 42.2, 39.7, 36.2, 35.0, 34.7, 33.4, 32.6, 32.3, 28.8, 26.2, 22.4, 16.6, 11.3.

embedded image

(3S,4aR,6aR,7aS,10aR,11aR,11bR)-7a,11b-Dimethyl-3-hydroxy-2,3,4,4a,5,6,6a,7,7a,10,10a,11,11a,11b-tetradeca hydro-1H-cyclopenta[b]phenanthren-8-carbonitrile (27)

To compound 26 (125 mg, 0.36 mmol) in methanol (9 mL) and dichloromethane (3 mL) was added 6 N HCl (10 ml) at room temperature. After 14 h, the mixture was extracted with dichloromethane (50 mL×2). The combined extracts were dried, filtered, and concentrated. The residue was purified by flash column chromatography (silica gel eluted with 25% EtOAc in hexanes) to afford compound 27 (101 mg, 93%): mp 170-172° C., [α]_D²⁵+5.4 (c 0.24, CHCl₃); ¹H NMR (CDCl₃) δ 6.61 (t, J=2.8 Hz, 1H), 4.04-4.02 (m, 1H), 0.89 (s, 3H), 0.78 (s, 3H); ¹³C NMR (CDCl₃) δ 147.7, 127.3, 116.0, 66.3, 55.1, 50.5, 48.1, 42.2, 39.1, 36.4, 35.7, 35.0, 34.8, 32.3, 32.0, 28.8, 28.7, 22.4, 16.6, 11.1; IR ν_max3391, 2216, 1448 cm⁻¹. Anal. Calcd for (C₂₀H₂₉NO): C, 80.22; H, 9.76; N, 4.68. Found: C, 80.32; H, 9.70; N, 4.72.

embedded image

(3S,4aR,6aR,7aS,8S,10aS,11aR,11bR)-Hexadecahydro-7a,11b-dimethyl-3-hydroxy-1H-cyclopenta[b]phenanthrene-8-carbonitrile (28)

To a solution of the compound 27 (60 mg, 0.2 mmol) in EtOAc (40 mL) was added Pd/C (30 mg). Hydrogenation was carried out under 5 atm H₂at room temperature for 3 h. The reaction was filtered through Celite which was washed with EtOAc (100 mL). Solvents were removed and the residue was purified by flash column chromatography (silica gel eluted with 10% EtOAc in hexanes) to afford compound 28 (54 mg, 90%): mp 145-147° C., [α]_D²⁵+45.3 (c 0.23, CHCl₃); ¹H NMR (CDCl₃) δ 4.05 (s, br, 1H), 2.27 (t, J=9.3 Hz, 1H), 0.89 (s, 3H), 0.78 (s, 3H); ¹³C NMR (CDCl₃) δ 121.5, 66.5, 54.4, 48.6, 45.6, 44.3, 39.9, 39.2, 36.4, 35.7, 34.8, 32.1, 32.0, 28.8, 28.7, 26.6, 26.5, 24.1, 14.4, 11.2; IR ν_max3434, 2235, 1449 cm⁻¹. Anal. Calcd for (C₂₀H₃₁NO): C, 79.68; H, 10.36; N, 4.65. Found: C, 79.47; H, 10.67; N, 4.77.

embedded image

In accordance with Scheme 7, the following compounds were prepared, using methods generally known in the art and as outlined below.

embedded image

(1R,7aR)-1-(1,1-Dimethylethoxyl)-2,3,5,6,7,7a-hexahydro-7a-methyl-5-oxo-1H-Indene-4-carboxylic acid (29)

Compound 29 was prepared as described previously (see Rychnovsky & Mickus, “Synthesis of ent-cholesterol, the unnatural enantiomer,” J. of Org. Chem., Vol. 57(9), pages 2732-2736 (1992)).

embedded image

(1R,3aR,7a)-1-(1,1-Dimethylethoxy)octahydro-7a-methyl-5H-inden-5-one (30)

Compound 29 (24.6 g, 0.92 mol) was dissolved in MeOH (200 mL) and 5% palladium on BaSO₄(3.0 g) was added. The mixture was cooled to 0° C. and hydrogenated (500 psi, H₂) for 2 h. The catalyst was removed by filtration through Celite. MeOH was then removed in reduced pressure to give a brown viscous oil. This viscous oil was heated up to 90° C. under high vacuum for 2 h and decarboxylation occurred at this time. The crude ¹H NMR shows a trans/cis ring fusion ratio of 6:1. The mixture was purified by flash column chromatography (silica gel eluted with 10% EtOAc in hexanes) to afford trans ring fused compound 30 (11.5 g, 56%): [α]_D²⁵−92.4 (c 0.62, CHCl₃); ¹H NMR (CDCl₃) δ 3.46 (t, J=7.4 Hz, 1H), 1.11 (s, 9H), 0.94 (d, J=0.5 Hz, 3H); ¹³C NMR (CDCl₃) δ 211.7, 79.3, 72.4, 44.5, 42.8, 41.9, 37.3, 35.1, 31.7, 28.6, 25.7, 10.1; IR ν_max1716, 1362 cm⁻¹. Anal. Calcd for (C₁₄H₂₄O₄): C, 74.95: H, 10.78. Found: C, 74.70; H, 10.43.

embedded image

(3R,3aR,7aR)-3-(1,1-Dimethylethoxy)-2,3,3a,4,7,7a-Hexahydro-6-hydroxy-3a-methyl-1H-indene-5-carboxylic acid, methyl ester (31)

Dimethyl carbonate (8.1 g, 90 mmol) was added to a suspension of sodium hydride (4.32 g, 60% in mineral oil, 100 mmol) in THF (200 mL) at room temperature. The reaction was refluxed for 30 min. Compound 30 (6.7 g, 30 mmol) in THF (50 mL) was added by syringe. The reaction was refluxed for 14 h and cooled down to room temperature. Acetic acid was slowly added to the mixture until pH 4-5 and water (100 mL) was added. The product was extracted into EtOAc (150 mL×3) and the combined extracts were dried. The solution was filtered and solvents were removed under reduced pressure. The residue was purified by flash column chromatography (silica gel eluted with 5% EtOAc in hexanes) to afford compound 31 (7.2 g, 85%): [α]_D²⁰=−98.6 (c 0.365, CHCl₃); ¹H NMR (CDCl₃) δ 12.18 (s, 1H), 3.61 (s, 3H), 3.52 (t, J=7.6 Hz, 1H), 1.03 (s, 9H), 0.58 (s, 3H); ¹³C NMR (CDCl₃) δ 173.4, 172.0, 96.6, 79.8, 72.2, 51.1, 41.3, 39.6, 34.8, 31.9, 31.3, 28.6, 25.5, 10.4; ν_max1652, 1608 cm⁻¹. Anal. Calcd for (C₁₆H₂₆O₄): C, 68.06; H, 9.28. Found: C, 67.81; H, 9.41.

embedded image

(3R,3aR,7aR)-3-(1,1-Dimethylethoxy)octahydro-3a-methyl-6-oxo-5-(3-oxo-7-octen-1-yl)-1H-indene-5-carboxylic acid, methyl ester (32)

Neutral alumina (15 g) was heated in a flask at 180° C. under high vacuum for 4 h. After cooling down to room temperature, the flask was filled with N₂. Compound 31 (7.2 g, 25.5 mmol), 1,7-octadien-3-one (4.3 g, 30 mmol), and CH₂Cl₂(30 mL) were added to the anhydrous alumina at room temperature. The mixture was stirred at room temperature for 16 h. The suspension was filtered through Celite® 545 which was washed with CH₂Cl₂(100 mL×3). The solvent was removed under reduced pressure and the residue was purified by flash column chromatography (silica gel eluted with 10% EtOAc in hexanes) to afford compound 32 (9.4 g, 91%). The compound is a mixture of diastereomers at position C-5 in a 3 to 1 ratio. The major diastereomer had: ¹H NMR (CDCl₃) δ 5.72-5.60 (m, 1H), 4.95-4.86 (m, 2H), 3.64 (s, 3H), 3.35 (t, J=7.1 Hz, 1H), 1.05 (s, 9H), 0.75 (s, 3H); ¹³C NMR (CDCl₃) δ 209.5, 208.0, 173.7, 137.8, 115.0, 79.9, 72.4, 56.2, 52.2, 46.9, 45.5, 42.4, 42.1, 41.7, 38.1, 32.9, 31.3, 30.5, 28.6, 28.4, 25.5, 22.6; IR ν_max1714, 1641, 1435 cm⁻¹. Anal. Calcd for (C₂₄H₃₈O₅): C, 70.90; H, 9.42. Found: C, 71.16; H, 9.70.

embedded image

(1R,3aR,8aS,9aR)-5-(3-Buten-1-yl)-1(1,1-dimethylethoxy)-1,2,3,3a,4,7,8,8a,9,9a-decahydro-9a-methyl-6H-benz[t]inden-6-one (33)

Lithium chloride (3.0 g, 70 mmol) was added to compound 32 (9.4 g, 23 mmoL) in anhydrous DMF (110 mL) at room temperature. The mixture was refluxed for 16 h to cause decarboxylation and the solvent was removed under reduced pressure. The crude decarboxylation product was dissolved in EtOH (30 mL) and 0.5 N NaOH (30 mL) was added at room temperature and then the reaction was refluxed and monitored by TLC. After 30 min, ring closure was complete and the reaction was cooled to room temperature. Aqueous NH₄Cl was added and the product was extracted into EtOAc (100 mL×3) and dried. The combined extracts were filtered and evaporated under reduced pressure. The residue was purified by flash column chromatography (silica gel eluted with 10% EtOAc in hexanes) to afford compound 33 (4.80 g, 55%) as a colorless oil: [α]_D²⁵−76.8 (c 1.10, CHCl₃); ¹H NMR (CDCl₃) δ 5.79-5.68 (m, 1H), 4.96-4.85 (m, 2H), 3.39 (t, J=8.8 Hz, 1H), 1.09 (s, 9H), 0.82 (s, 3H); ¹³C NMR (CDCl₃) δ 198.7, 159.3, 138.1, 133.6, 114.3, 79.7, 72.0, 45.3, 44.3, 42.0, 37.4, 34.7, 33.3, 31.1, 30.8, 29.8, 28.5, 25.6, 24.3, 10.7; IR ν_max2972, 1667, 1361 cm⁻¹. Anal. Cacld for (C₂₂H₃₄O₂): C, 79.95; H, 10.37. Found: C, 79.82; H, 10.51.

embedded image

(1R,3aR,4aS,5aR,8aS,9aR)-5-(3-Buten-1-yl)-1-(1,1-dimethylethoxy)dodecahydro-9a-methyl-6H-benz[t]inden-6-one (34)

A three-neck flask equipped with a dry ice condenser was cooled to −78° C. and anhydrous ammonia (100 mL) was condensed into the flask. Lithium (0.73 g, 91 mmol, 7 equiv) was added and the resulting blue solution was stirred for 0.5 h. To this was added a solution of compound 33 (4.2 g, 13 mmol) in dry THF (100 mL). After 3 h of stirring, solid NH₄Cl was added until the blue color disappeared, and the reaction mixture was allowed to warm to room temperature overnight. Aqueous NH₄Cl was added and the product was extracted into EtOAc (100 mL×3). The combined extracts were dried, filtered, and concentrated. Flash column chromatography (silica gel eluted with 10% EtOAc in hexanes) gave compound 34 (2.97 g, 71%) as a white semisolid: [α]_D²⁵−45.4 (c 0.26, CHCl₃); ¹H NMR (CDCl3) δ 5.77-5.68 (m, 1H), 4.95-4.84 (m, 2H), 3.35 (t, J=7.4 Hz, 1H), 1.07 (s, 9H), 0.73 (s, 3H); ¹³C NMR (CDCl3) δ 212.1, 139.1, 114.5, 80.6, 72.2, 54.6, 48.7, 44.6, 44.4, 42.8, 42.2, 37.8, 34.5, 31.4 (2×C), 30.5, 28.9, 25.8, 24.4, 11.9; IR ν_max1712, 1361 cm⁻¹. Anal. Calcd for (C₂₂H₃₆O₂): C, 79.46; H, 10.91. Found: C, 79.26; H, 11.19.

embedded image

(1R,3aR,4aS,5R,8aS,9aR)-1-(1,1-Dimethylethoxy)dodecahydro-9a-methyl-5-(3-oxobutyl)-6H-benz[t]inden-6-one (35)

A suspension of PdCl₂(36 mg, 0.2 mmol) and CuCl (842 mg, 8.5 mmol) was stirred in DMF/H₂O (15 mL, v/v=9/1) at room temperature under O₂for 1 h. Compound 34 (2.80 g, 8.4 mmol) in DMF/H₂O (30 mL, v/v=9/1) was added by syringe. The reaction was stirred and monitored by TLC. After 20 h, water (40 mL) was added and the product extracted into EtOAc (50 mL×3). The combined extracts were dried, filtered, and concentrated. The residue was purified by flash column chromatography (silica gel eluted with 10% EtOAc in hexanes) to give compound 35 (1.90 g, 64%) as a white semisolid: [α]_D²⁵−32.5 (c 0.16, CHCl₃); ¹H NMR (CDCl₃) δ 3.33 (t, J=7.2 Hz, 1H), 2.49-2.09 (m, 5H), 2.04 (s, 3H), 1.05 (s, 9H), 0.71 (s, 3H); ¹³C NMR (CDCl₃) δ 212.1, 208.7, 80.2, 72.0, 54.0, 48.4, 44.3, 44.0, 42.5, 42.0, 40.9, 37.4, 34.2, 31.1, 30.1, 29.6, 28.6, 25.5, 19.2, 11.6; IR ν_max1711, 1360 cm⁻¹. Anal. Calcd for (C₂₂H₃₆O₃): C, 75.82; H, 10.41. Found: C, 75.69; H, 10.54.

embedded image

(6aS,7aR,8R,10aR,11aS,11bR)-1,2,5,6,6a,7,7a,8,9,10,10a,11,11a,11b-Tetradecahydro-8-hydroxy-7a-methyl-3H-cyclopenta[b]phenanthren-3-one (36)

To a solution of compound 35 (1.85 g, 5.3 mmol) in MeOH (50 mL) was added 3 N HCl (25 mL) at room temperature. The reaction was stirred and refluxed for 16 h. After cooling to room temperature, the product was extracted into dichloromethane (50 mL×3). The combined extracts were dried, filtered, and concentrated. The residue was purified by flash column chromatography (silica gel eluted with 20% EtOAc in hexanes) to give compound 36 (1.21 g, 81%) as a white semisolid: [α]_D²⁵+33.4 (c 0.30, CHCl₃); ¹H NMR (CDCl₃) δ 5.69 (s, 1H), 3.55 (t, J=8.0 Hz, 1H), 0.67 (s, 3H); ¹³C NMR (CDCl₃) δ 199.7, 167.0, 124.0, 80.9, 49.2, 44.4, 43.8, 42.6, 42.4, 36.9, 35.9, 35.5, 33.7, 29.9, 29.2, 25.7, 25.0, 10.9.

embedded image

In accordance with Scheme 8, the following compounds were prepared, using methods generally known in the art and as outlined below.

embedded image

(4aS,6aS,7aR,8R,10aR,11aS,11bS)-Hexadecahydro-8-hydroxy-7a-methyl-3H-cyclopenta[b]phenanthren-3-one (37)

A three-neck flask fitted with a dry ice condenser was cooled to −78° C., and anhydrous ammonia (100 mL) was condensed into the flask. Lithium (0.21 g, 30 mmol) was added, and the resulting blue solution was stirred for 0.5 h. To this was added a solution of compound 36 (820 mg, 3.0 mmol) in dry THF (30 mL). After 3 h, solid NH₄Cl was added until the blue color disappeared. The cooling bath was removed and stirring was continued at room temperature overnight. Aqueous NH₄Cl was added and the product was extracted into EtOAc (100 mL×3). The combined extracts were washed with brine, dried and the solvent evaporated. Flash column chromatography (silica gel eluted with 10% EtOAc in hexanes) gave compound 37 (615 mg, 75%) as a white solid: [α]_D²⁵+52.3 (c 0.13, CHCl₃); ¹H NMR (CDCl₃) δ 3.58 (t, J=7.7 Hz, 1H), 0.68 (s, 3H); ¹³C NMR (CDCl₃) δ 211.7, 81.3, 48.3, 47.8, 45.7, 44.9, 44.5, 43.6, 42.9, 41.0, 37.8, 34.2, 33.7, 30.1, 29.9, 29.0, 25.3, 11.0; IR ν_max3419, 1713 cm⁻¹. Anal. Calcd for (C₁₈H₂₈O₂): C, 78.21; H, 10.21. Found: C, 78.29; H, 10.12.

embedded image

(4aS,6aS,7aR,10aR,11aS,11bS)-Dodecahydro-7a-methyl-1H-cyclopenta[b]phenanthrene-3,8(2H,4H)-dione (38)

Jones reagent was added to a solution of compound 37 (605 mg, 2.2 mmol) in acetone (40 mL) at 0° C. until a brown-yellowish color persisted. After 10 min, 2-propanol (1.0 mL) was added to consume excess oxidant. Brine (50 mL) was added and the product extracted into EtOAc (50 mL×3). The combined extracts were dried, filtered, and concentrated. The residue was purified by flash column chromatography (silica gel eluted with 20% EtOAc in hexanes) to give compound 38 (580 mg, 96%) as a white solid: [α]_D²⁵−13.1 (c 0.145, CHCl₃); ¹H NMR (CDCl₃) δ 0.81 (s, 3H); ¹³C NMR (CDCl₃) δ 220.1, 211.0, 48.2, 47.8, 47.6, 45.6, 45.4, 43.5, 40.9, 38.9, 37.6, 3.54, 34.0, 33.4, 29.9, 28.7, 23.8, 13.4; IR ν_max1716, 1715 cm⁻¹.

embedded image

(3R,4aS,6aS,7aR,10aR,11aS,11bS)-Hexadecahydro-3-hydroxy-7a-methyl-8H-cyclopenta[b]phenanthren-8-one (39)

To a solution of compound 38 (570 mg, 2.1 mmoL) in THF (20 mL) was added K-selectride (2.6 mmol, 2.6 mL, 1.0 M in THF) at −78° C. After 3 h, aqueous 10% NaOH (30 mL) and 30% H₂O₂(20 mL) were added at −78° C. After addition, the reaction was warmed up to room temperature for 1 h. The product was extracted into EtOAc (50 mL×3), and the combined extracts were dried, filtered and concentrated. The residue was purified by flash column chromatography (silica gel eluted with 30% EtOAc in hexanes) to give compound 39 (456 mg, 80%) as a white solid: mp 143-145° C., [α]_D²⁵−41.0 (c 0.19, CHCl₃); ¹H NMR (CDCl₃) δ 3.95-3.90 (m, 1H), 0.75 (s, 3H); ¹³C NMR (CDCl₃) δ 220.8, 65.8, 48.1, 47.5, 46.9, 45.4, 40.2, 39.1, 37.8, 35.8, 35.4, 33.8, 33.7, 32.5, 28.1, 23.8, 23.1, 13.3; IR ν_max3422, 1737 cm⁻¹; Anal. Calcd for (C₁₈H₂₅O₂): C, 78.21; H, 10.21. Found: C, 78.29; H, 10.43.

embedded image

(3R,4aS,6aS,7aR,10aS,11aS,11bS)-9(E)-Benzylidene-3-hydroxy-7a-methyl-hexadecahydro-8H-cyclopenta[b]phenanthren-8-one (40)

To a solution of compound 39 (100 mg, 0.36 mmol) in ethanol (10 mL) was added benzaldehyde (97 mg, 0.9 mmol) and KOH (50 mg) at room temperature. After 16 h, aqueous NH₄Cl (50 mL) was added and the product extracted into EtOAc (50 mL×3). The combined extracts were dried, filtered, and concentrated. The residue was purified by flash column chromatography (silica gel eluted with 20% EtOAc in hexanes) to give compound 40 (130 mg, 100%) as a white solid: [α]_D²⁵−15.7 (c 0.14, CHCl₃); ¹H NMR (CDCl₃) δ 7.46-7.22 (m, 5H), 4.01 (s, 1H), 2.79 (dd, J=15.7 Hz, 6.1 Hz, 1H), 0.87 (s, 3H); ¹³C NMR (CDCl₃) δ 209.5, 136.0, 135.6, 132.7, 130.2, 129.0, 128.5, 66.2, 48.5, 47.5, 47.1, 43.8, 40.4, 39.4, 38.1, 36.1, 34.0, 33.9, 32.8, 31.4, 27.8, 23.3, 14.3; IR ν_max3425, 1714, 1632 cm⁻¹. Anal. Calcd for (C₂₅H₃₂O₂): C, 82.37; H, 8.85. Found: C, 82.28; H, 9.06.

embedded image

(3R,4aS,6aS,7aR,8R,10aS,11aS,11bS)-9(E)-Benzylidene-7a-methyl-hexadecahydro-cyclopenta[b]phenanthren-3,8-diol (41)

To a solution of compound 40 (128 mg, 0.36 mmol) in ethanol (20 mL) was added CeCl₃.7H₂O (559 mg, 1.5 mmol) and NaBH₄(57 mg, 1.5 mmol) at 0° C. After 1 h, aqueous NH₄Cl (50 mL) was added and the product was extracted into EtOAc (50 mL×3). The combined extracts were dried, filtered, and concentrated. The residue was purified by flash column chromatography (silica gel eluted with 30% EtOAc in hexanes) to give compound 41 (129 mg, 100%) as a white solid: [α]_D²⁵+85.8 (c 0.365, CHCl₃); ¹H NMR (CDCl₃) δ 7.40-7.25 (m, 5H), 6.44 (s, 1H), 4.04 (s, 1H), 3.99 (s, 1H), 2.59 (dd, J=16.5 Hz, 6.3 Hz, 1H), 0.62 (s, 3H); ¹³C NMR (CDCl₃) δ 146.1, 138.1, 128.5, 128.4, 126.4, 123.1, 85.2, 66.7, 48.7, 47.4, 44.6, 43.1, 42.8, 40.6, 38.6, 36.4, 34.4, 34.2, 33.2, 32.9, 28.2, 23.5, 11.4; IR ν_max3384 cm⁻¹. Anal. Calcd for (C₂₅H₃₄O₂): C, 81.92; H, 9.35. Found: C, 81.74; H, 9.55.

embedded image

(3R,4aS,6aS,7aR,8R,10aS,11aS,11bS)-9(E)-Benzylidene-7a-methyl-hexadecahydro-cyclopenta[b]phenanthren-3,8-diol, diacetate (42)

To a solution of compound 41 (127 mg, 0.36 mmol) in dichloromethane (20 mL) was added Ac₂O (204.2 mg, 2.0 mmol), Et₃N (303.6 mg, 3.0 mmol) and DMAP (5 mg) at room temperature. After 30 min, water was added and the product extracted into dichloromethane (50 mL×3). The combined extracts were dried, filtered, and concentrated. The residue was purified by flash column chromatography (silica gel eluted with 25% EtOAc in hexanes) to give compound 42 (156 mg, 100%) as a white solid [α]_D²⁵+48.3 (c 0.12, CHCl₃); ¹H NMR (CDCl₃) δ 7.28-7.08 (m, 5H), 6.14 (d, J=1.9 Hz, 1H), 5.30 (s, 1H), 4.97 (s, 1H), 2.59 (dd, J=16.5 Hz, 6.9 Hz, 1H), 2.25-2.15 (m, 1H), 2.12 (s, 3H), 1.97 (s, 3H), 0.70 (s, 3H); ¹³C NMR (CDCl₃) δ 171.0, 170.5, 140.8, 137.5, 128.2, 126.4, 123.6, 84.5, 69.8, 48.2, 46.7, 44.4, 43.0, 42.8, 38.2, 37.4, 36.9, 34.0, 33.8, 32.9, 29.9, 27.9, 23.9, 21.3, 21.0, 12.2; IR ν_max1735, 1368, 1238 cm⁻¹. Anal. Calcd for (C₂₉H₃₈O₄): C, 77.30; H, 8.50. Found: C, 77.50; H, 8.60.

embedded image

(3R,4aS,6aS,7aR,8S,10aS,11aS,11bS)-3,8-Dihydroxy-7a-methyl-hexadecahydro-9H-cyclopenta[b]phenanthren-9-one, diacetate (43)

Compound 42 (154 mg, 0.34 mmol) was dissolved in methanol (40 mL) and EtOAc (20 mL) and cooled to −78° C. Ozone was bubbled through the solution for 30 min. Then Me₂S (5 mL) was added at −78° C., the cooling bath removed and stirring continued at room temperature for 16 h. Solvents were dried, filtered, and concentrated. The residue was purified by flash column chromatography (silica gel eluted with 20% EtOAc in hexanes) to give compound 43 (128 mg, 97%) as a white solid [α]_D²⁵+161.7 (c 0.12, CHCl₃); ¹H NMR (CDCl₃) δ 4.99-4.96 (m, 2H), 2.26-2.23 (m, 1H), 2.10 (s, 3H), 1.98 (s, 3H), 0.77 (s, 3H); ¹³C NMR (CDCl₃) δ 211.0, 170.7, 170.4, 85.7, 69.8, 48.3, 46.8, 44.2, 41.9, 39.5, 38.2, 38.1, 37.5, 37.0, 33.9, 33.8, 30.0, 27.4, 24.0, 21.5, 20.8, 12.6; IR ν_max1763, 1736 cm⁻¹. MS (FAB) for [C₂₂H₃₂O₅+H]⁺: 377.2328. Found: 377.2328.

embedded image

(3R,4aS,6aS,7aS,10aS,11aS,11bS)-3-Hydroxy-7a-methyl-hexadeca hydro-9H-cyclopenta[b]phenanthren-9-one, acetate (44)

Freshly prepared samarium filings (300 mg, 2.0 mmol) were added to THF (5 mL) followed by iodide (435 mg, 1.5 mmol) addition in THF (5 mL). The mixture was stirred under N₂for 1 h until it became a deep blue solution. Compound 43 (126 mg, 0.335 mmol) in THF (8 mL) and methanol (2 mL) was added. After 1 h, aqueous Na₂CO₃(30 mL) was added and the product extracted into EtOAc (50 mL×3). The combined extracts were dried, filtered, and concentrated. The residue was purified by flash column chromatography (silica gel eluted with 20% EtOAc in hexanes) to give compound 44 (105 mg, 99%) as a white solid [α]_D²⁵+166.2 (c 0.13, CHCl₃); ¹H NMR (CDCl₃) δ 5.01-4.99 (m, 1H), 2.17-1.97 (m, 3H), 2.00 (s, 3H), 0.84 (s, 3H); ¹³C NMR (CDCl₃) δ 218.3, 170.4, 69.7, 55.3, 48.4, 46.7, 46.0, 45.6, 41.1, 38.9, 38.4, 37.4, 36.9, 33.9, 33.7, 29.9, 27.5, 23.9, 21.3, 18.0; IR ν_max1736, 1244 cm⁻¹. MS (FAB) for [C₂₀H₃₀O₃+H]⁺: 319.2273. Found: 319.2273.

embedded image

(3R,4aS,6aS,7aS,10aS,11aS,11bS)-3-Hydroxy-7a-methyl-hexadeca hydro-9H-cyclopenta[b]phenanthren-9-one (45)

To a solution of compound 44 (100 mg, 0.31 mmol) in methanol (20 mL) and water (2 mL) was added K₂CO₃(500 mg, 3.6 mmol) at room temperature and the reaction was refluxed for 2 h. After cooling to room temperature, brine (30 mL) was added and the product was extracted into EtOAc (50 mL×3). The combined extracts were dried, filtered and concentrated. The residue was purified by flash column chromatography (silica gel eluted with 30% EtOAc in hexanes) to give compound 45 (70 mg, 81%) as a white solid: mp 165-166° C.; [α]_D²⁵+205.3 (c, CHCl₃); ¹H NMR (CDCl₃) δ 4.10 (s, 1H), 0.88 (s, 3H); ¹³C NMR (CDCl₃) δ 218.7, 66.2, 55.4, 48.5, 47.1, 46.0, 45.6, 41.2, 40.4, 39.0, 38.5, 36.1, 34.0, 33.9, 32.8, 27.6, 23.2, 18.0; IR ν_max3427, 1742 cm⁻¹. MS (FAB) for [C₁₈H₂₈O₂]⁺: 276.2089. Found: 276.2086.

embedded image

In accordance with Scheme 9, the following compounds were prepared, using methods generally known in the art and as outlined below.

embedded image

(2′R,3R,4aS,6aS,7aR,10aR,11aS,11bS)-Hexadecahydro-7a-methyl-spiro[8H-cyclopenta[b]phenanthrene-8,2′-oxiran]-3-ol (46)

To a solution of compound 45 (45 mg, 0.16 mmol) in DMSO (3 mL) was added trimethylsulfonium iodide (202 mg, 1.0 mmol) and potassium tert-butoxide (112 mg, 1.0 mmol) at room temperature. After 3 h, water was added (20 mL) and the product extracted into EtOAc (50 mL×3). The combined extracts were dried, filtered, and concentrated. The residue was purified by flash column chromatography (silica gel eluted with 30% EtOAc in hexanes) to give compound 46 (35 mg, 75%) as a white solid: mp 165-167° C.; [α]_D²⁵+20.0 (c 0.12, CHCl₃); ¹H NMR (CDCl₃) δ 4.08 (s, 1H), 2.90 (d, J=15.2 Hz, 1H), 2.60 (d, J=15.2 Hz, 1H), 0.87 (s, 3H); ¹³C NMR (CDCl₃) δ 70.5, 66.5, 53.6, 48.3, 47.2, 47.0, 42.1, 40.4, 40.2, 37.9, 36.2, 34.2, 34.0, 32.8, 29.0, 28.8, 25.8, 23.3, 14.3; IR ν_max3418, 1443, 1378, 851 cm⁻¹. MS (FAB) for [C₁₉H₃₀O₂]⁺: 290.2246. Found: 290.2243.

embedded image

(3R,4aS,6aS,7aR,10aR,11aS,11bS)-3-(Methoxymethoxy)-7a-methyl-hexadecahydro-8H-cyclopenta[b]phenanthren-8-one (47)

To a solution of compound 46 (200 mg, 0.72 mmol) in dry dichloromethane (10 mL) was added N,N-diisopropylethylamine (260 mg, 2.0 mmol) and chloromethyl methyl ether (241 mg, 3.0 mmol) at room temperature. After 16 h, water (30 mL) was added and the product extracted into dichloromethane (50 mL×3). The combined extracts were dried, filtered and concentrated. The residue was purified by flash column chromatography (silica gel eluted with 10% EtOAc in hexanes) to give compound 47 (230 mg, 100%) as a white solid: [α]_D²⁵−40.0 (c 0.20, CHCl₃); ¹H NMR (CDCl₃) δ 4.60 (s, 2H), 3.83-3.82 (m, 1H), 3.31 (s, 3H), 0.81 (s, 3H); ¹³C NMR (CDCl₃) δ 220.9, 94.5, 71.2, 55.0, 48.3, 47.7, 46.9, 45.6, 39.3, 38.1, 37.9, 36.6, 35.6, 33.9, 30.2, 28.3, 24.0, 2.39, 13.5; IR ν_max1740 cm⁻¹.

embedded image

1,1,1-Trifluoromethanesulfonic acid (3R,4aS,6aS,7aR,10aS,11aS,11bS)-3-(Methoxymethoxy)-7a-methyl-2,3,4,4a,5,6,6a,7,7a,10,10a,11,11a,11b-tetradecahydro-1H-cyclopenta[b]phenanthren-8-yl ester (48)

To a solution of compound 47 (230 mg, 0.72 mmol) in THF (10 mL) was added KHMDS (1.5 mmol, 0.5 M in toluene) at −78° C. After 30 min, N-phenyltrifluoromethanesulfonimide (536 mg, 1.5 mmol) in THF (5 mL) was added at −78° C. After 2 h, aqueous NH₄Cl (50 mL) was added and the product extracted into EtOAc (50 mL×3). The combined extracts were dried, filtered and concentrated. The residue was purified by flash column chromatography (silica gel eluted with 10% EtOAc in hexanes) to give compound 48 (350 mg containing an aromatic impurity from the sulfonamide reagent): ¹H NMR (CDCl₃) δ 5.54 (d, J=1.7 Hz, 1H), 4.63 (s, 2H), 3.86-3.85 (m, 1H), 3.34 (s, 3H), 0.96 (s, 3H); ¹³C NMR (CDCl₃) δ 159.6, 114.4, 94.5, 71.3, 55.0, 49.0, 48.9, 47.0, 44.9, 40.4, 38.2, 36.8, 34.0, 33.9, 30.6, 30.2, 26.7, 23.9, 15.5.

embedded image

(3R,4aS,6aS,7aR,10aS,11aS,11bS)-3-(Methoxymethoxy)-7a-methyl-2,3,4,4a,5,6,6a,7,7a,10,10a,11,11a,11b-tetradecahydro-1H-cyclopenta[b]phenanthrene-8-carbonitrile (49)

To compound 49 (350 mg containing the impurity carried over from compound 48) in acetonitrile (20 mL) was added sodium cyanide (103 mg, 2.1 mmol), copper (I) iodide (28 mg, 0.14 mmol) and Pd(PPh₃)₄(37 mg, 0.035 mmol). The reaction was refluxed for 16 h. After cooling to room temperature, aqueous NH₄Cl (50 mL) was added and the product was extracted into dichloromethane (50 mL×3). The combined extracts were dried, filtered and concentrated. The residue was purified by flash column chromatography (silica gel eluted with 10% EtOAc in hexanes) to give compound 49 (250 mg, containing the aromatic impurity carried over from compound 48): ¹H NMR (CDCl₃) δ 6.60-6.58 (m, 1H), 4.64 (s, 2H), 3.85-3.80 (m, 1H), 3.34 (s, 3H), 0.85 (s, 3H); ¹³C NMR (CDCl₃) δ 147.5, 127.6, 116.1, 94.3, 71.8, 54.9, 50.4, 48.9, 48.3, 46.8, 41.6, 38.4, 37.9, 36.7, 34.9, 33.9 (2C), 30.0, 26.5, 23.8, 16.4. MS (FAB) for [C₂₁H₃₁NO₂+Na]⁺: 352.2252. Found: 352.2252.

embedded image

(3R,4aS,6aS,7aR,8R,10aS,11aS,11bS)-3-(Methoxymethoxy)-7a-methyl-hexadecahydro-cyclopenta[b]phenanthrene-8-carbonitrile (50)

To a solution of compound 49 (250 mg containing the aromatic impurity carried over from compound 48) in EtOAc (40 mL) was added Pd/C (100 mg) at room temperature. Hydrogenation was carried out under 60 psi H₂. After 3 h, the pressure was released and the mixture was filtered through Celite which was washed with EtOAc (100 mL). Solvent was removed and the residue was purified by flash column chromatography (silica gel eluted with 10% EtOAc in hexanes) to give compound 50 (250 mg containing the aromatic impurity carried over from compound 48): ¹H NMR (CDCl₃) δ 4.64 (s, 2H), 3.85-3.80 (m, 1H), 3.34 (s, 3H), 0.83 (s, 3H); ¹³C NMR (CDCl₃) δ 121.2, 94.3, 71.8, 54.9, 48.3, 47.9, 46.7, 44.9, 44.4, 39.7, 38.1, 37.9, 36.6, 33.8, 33.7, 30.0, 28.3, 26.3, 26.2, 23.7, 14.2.

embedded image

(3R,4aS,6aS,7aR,8R,10aR,11aS,11bS)-3-Hydroxy-7a-methyl-hexadecahydro-cyclopenta[b]phenanthrene-8-carbonitrile (51)

To a solution of compound 50 (250 mg containing the aromatic impurity carried over from compound 48) in methanol (30 mL) was added 6 N HCl (15 mL) at room temperature. After 4 h, the product was extracted into dichloromethane (50 mL×3), and the combined extracts were dried, filtered, and concentrated. The residue was purified by flash column chromatography (silica gel eluted with 25% EtOAc in hexanes) to give compound 51 (84 mg): mp. 163-165° C.; [α]_D²⁵−33.9 (c 0.18, CHCl₃); ¹H NMR (CDCl₃) δ 4.06-4.00 (m, 1H), 0.88 (s, 3H); ¹³C NMR (CDCl₃) δ 121.4, 66.2, 48.4, 48.0, 47.0, 45.0, 44.2, 40.3, 39.8, 38.1, 36.0, 33.9, 33.8, 32.7, 28.4, 26.4 (2×C), 23.2, 14.2; IR ν_max3456, 2235 cm⁻¹. Anal. Calcd for (C₁₉H₂₉NO): C, 79.39; H, 10.17. Found: C, 79.16; H, 10.14.

embedded image

1-[(3R,4aS,6aS,7aR,8R,10aR,11aS,11bS)(3-Hydroxy-7a-methyl-hexadecahydro-cyclopenta[b]phenanthren-8-yl]-ethanone (52)

To a solution of compound 51 (60 mg, 0.2 mmol) in THF (10 mL) was added methyl magnesiumbromide (2 mmol, 3 M in ether, 0.67 mL) at room temperature. The reaction was refluxed for 16 h and then cooled to room temperature. Aqueous NH₄Cl (30 mL) was added and after stirring was continued for 30 min, the product was extracted into EtOAc (50 mL×3). The combined extracts were dried, filtered, and concentrated. The residue was purified by flash column chromatography (silica gel eluted with 25% EtOAc in hexanes) to give compound 52 (36 mg, 57%): mp 128-130° C.; [α]_D²⁵−72.3 (c 0.11, CHCl₃); ¹H NMR (CDCl₃) δ 4.09-4.05 (m, 1H), 2.55 (t, J=8.8 Hz, 1H), 2.12 (s, 3H), 0.60 (s, 3H); ¹³C NMR (CDCl₃) δ 209.8, 66.5, 63.6, 50.7, 48.2, 47.2 (2×C), 44.1, 40.4, 38.4, 36.2, 34.3, 34.0, 32.9, 31.5, 28.4, 26.5, 23.3, 22.6, 13.4; IR ν_max3387, 1703 cm⁻¹. MS (FAB) for [C₂₀H₃₂O₂+H]⁺: 305.2481. Found: 305.2487.

embedded image

In accordance with Scheme 10, the following compounds were prepared, using methods generally known in the art and as outlined below.

embedded image

(4aR,6aS,7aR,8R,10aR,11aS,11bS)-Hexadecahydro-8-hydroxy-7a-methyl-3H-cyclopenta[b]phenanthren-3-one (53)

To compound 36 (120 mg, 0.44 mmol) in pyridine (40 mL) was added Pd/C (100 mg) at room temperature. Hydrogenation was carried out under 60 psi H₂. After 3 h, the pressure was released and the mixture was filtered through Celite® 545 which was washed with EtOAc (100 mL). Solvents were removed and the residue was purified by flash column chromatography (silica gel eluted with 25% EtOAc in hexanes) to give compound 53 (120 mg, 4aR:4aS ratio 2.5:1): ¹H NMR (CDCl₃) 4aR diastereoisomer δ 3.66 (t, J=8.5 Hz, 1H), 2.58 (t, J=14.0 Hz, 1H), 2.24-0.79 (m, 23H), 0.72 (s, 3H); ¹³C NMR (CDCl₃) δ 213.2, 81.8, 45.3, 44.8, 43.3, 43.0, 40.2, 38.8, 38.6, 36.7, 31.1, 30.4, 29.1, 29.0, 27.4, 25.7, 11.4.

embedded image

(4aR,6aS,7aR,10aR,11aS,11bS)-Dodecahydro-7a-methyl-1H-cyclopenta[b]phenanthrene-3,8(2H,4H)-dione (54)

Jones reagent was added to a solution of compound 53 (115 mg, 0.42 mmol) in acetone (20 mL) at 0° C. until a brown-yellowish color persisted. After 10 min, 2-propanol (1.0 mL) was added to consume excess oxidant and then brine (50 mL) was added. The product was extracted into EtOAc (50 mL×3), and the combined extracts were dried, filtered, and concentrated. The residue was purified by flash column chromatography (silica gel eluted with 25% EtOAc in hexanes) to give compound 54 (110 mg 4aR:4aS ratio 2.5:1) as a white solid: ¹H NMR (CDCl₃) δ 0.84 (s, 3H); ¹³C NMR (CDCl₃) 4aR diastereomer δ 220.3, 212.2, 47.8, 45.6, 42.6, 39.8, 39.0, 38.5, 38.2, 38.1, 36.3, 35.4, 30.7, 28.5, 28.4, 27.1, 23.9, 13.5.

embedded image

(4aR,6aS,7aR,10aR,11aS,11bS)-Hexadecahydro-3-hydroxy-7a-methyl-8H-cyclopenta[b]phenanthrene-8-one (55)

To a solution of compound 54 (110 mg, 0.4 mmol) in THF (10 mL) was added LiAl(O^tBu)₃H at 40° C. After 2 h, 3 N HCl, was added and the product extracted into EtOAc (50 mL×3). The combined extracts were dried, filtered and concentrated. The residue was purified by flash column chromatography (silica gel eluted with 25% EtOAc in hexanes) to give compound 55 (4aR separated from 4aS diastereomer, 65 mg, 56% from compound 36) as a white solid: mp 174-176° C.; [α]_D²⁵−36.2 (c 0.21, CHCl₃); ¹H NMR (CDCl₃) δ 3.65-3.55 (m, 1H), 0.82 (s, 3H); ¹³C NMR (CDCl₃) δ 221.1, 71.4, 47.9, 45.7, 40.1, 39.1, 38.8, 38.4, 36.2, 35.6, 35.5, 31.7, 29.6, 29.3, 28.4, 25.5, 24.0, 13.5; IR ν_max3460, 1738 cm⁻¹. Anal. Calcd for (C₁₈H₂₈O₂): C, 78.21; H, 10.21. Found: C, 78.37; H, 10.20.

embedded image

(2′R,3R,4aR,6aS,7aR,10aR,11aS,11bS)-Hexadecahydro-7a-methyl-Spiro[8H-cyclopenta[b]phenanthrene-8,2′-oxiran]-3-ol (56)

To a solution of compound 55 (40 mg, 0.144 mmol) in DSMO (3 mL) was added trimethylsulfonium iodide (204 mg, 1.0 mmol) and potassium tert-butoxide (112 mg, 1.0 mmol) at room temperature. After 3 h, water (20 mL) was added and the product extracted into EtOAc (50 mL×3). The combined extracts were dried, filtered and concentrated. The residue was purified by flash column chromatography (silica gel eluted with 30% EtOAc in hexanes) to give compound 56 (27 mg, 65%) as a white solid: mp 163-165° C.; [α]_D²⁵+16.7 (c 0.12, CHCl₃); ¹H NMR (CDCl₃) δ 3.64-3.60 (m, 1H), 2.90 (d, J=15.0 Hz, 1H), 2.61 (d, J=15.2 Hz, 1H), 0.86 (s, 3H); ¹³C NMR (CDCl₃) δ 71.7, 70.5, 53.6, 47.1, 41.6, 40.7, 39.1, 38.6, 38.1, 36.2, 35.1, 35.0, 33.6, 33.0, 30.4, 29.8, 28.9, 25.6, 14.5; IR ν_max3379, 1443, 1375 cm⁻¹. MS (FAB) for [C₁₉H₃₀O₂]⁺: 290.2246. Found: 290.2243.

[³⁵S]-TBPS Displacement

The IC₅₀values for non-competitive displacers of [³⁵S]-TBPS from the picrotoxin binding site on GABA_Areceptors are reported in Table 1.

TABLE 1

Inhibition of [³⁵S]-TBPS Binding (nM)

Compound
IC₅₀
n_Hill

Structure 1 Compounds

MQ-31
61 ± 4
1.02 ± 0.06

MQ-32
147 ± 9
0.97 ± 0.05

MQ-33
62 ± 6
0.92 ± 0.07

MQ-36
1,730 ± 120
1.26 ± 0.09

MQ-37
46 ± 4
1.29 ± 0.12

MQ-38
52 ± 7
1.06 ± 0.13

MQ-39
65 ± 7
0.89 ± 0.08

MQ-83
748 ± 103
1.08 ± 0.13

MQ-85
29 ± 7
0.93 ± 0.16

MQ-86
43 ± 3
0.89 ± 0.05

MQ-87
14 ± 2
0.79 ± 0.07

Structure 2 Compounds

MQ-47
1,330 ± 450
1.04 ± 0.29

MQ-48
282 ± 197
0.60 ± 0.21

MQ-49
1,580 ± 250
1.04 ± 0.14

MQ-50
1,060 ± 240
0.90 ± 0.15

MQ-51
5,860 ± 1,380
1.02 ± 0.13

MQ-53
3,630 ± 800
3.07 ± 2.34

MQ-54
1,990 ± 190
5.28 ± 1.13

Results presented are from duplicate experiments performed in triplicate. Error limits are calculated as standard error of the mean. Methods used are known in the art (see Jiang, X., et al., Neurosteroid analogues. 9. Conformationally constrained pregnanes: structure-activity studies of 13,24-cyclo-18,21-dinorcholane analogues of the GABA modulatory and anesthetic steroids (3α,5α)- and (3α,5α)-3-hydroxypregnan-20-one. J. Med. Chem., 46: 5334-48 (2003)—the contents of which are hereby incorporated by reference in their entirety).

Electrophysiology Results

The compounds of the present disclosure were evaluated for the ability to potentiate chloride currents mediated by 2 μM GABA at rat α₁β₂γ_2Ltype GABA_Areceptors expressed in Xenopus laevis oocytes and the results are shown in Table 2.

TABLE 2

Analogue Potentiation of GABA Effects at Rat α1β2γ2GABA_A

Receptors Expressed in Frog Oocytes

Com-
Oocyte electrophysiology

pound
0.1 μM
1.0 μM
10 μM
(gating) 10 μM

Structure 1 Compounds

MQ-31
1.49 ± 0.09
3.93 ± 0.20
8.25 ± 0.71
0.02 ± 0.02

MQ-32
1.64 ± 0.02
3.21 ± 0.13
8.77 ± 1.65
0.12 ± 0.01

MQ-33
1.68 ± 0.10
5.30 ± 0.75
9.08 ± 1.83
0.02 ± 0.01

MQ-36
1.11 ± 0.09
1.22 ± 0.05
3.81 ± 0.45
−0.06 ± 0.06

MQ-37
1.91 ± 0.17
16.12 ± 2.24
27.57 ± 5.45
0.54 ± 0.44

MQ-38
1.51 ± 0.19
6.92 ± 1.29
12.50 ± 1.98
0.51 ± 0.48

MQ-39
1.32 ± 0.03
3.82 ± 0.36
7.91 ± 0.64
0.03 ± 0.0

MQ-83
0.85 ± 0.07
1.03 ± 0.06
6.35 ± 0.81
0.1 ± 0.2

MQ-85
2.08 ± 0.23
9.59 ± 1.77
17.18 ± 3.31
0.10 ± 0.02

MQ-86
2.25 ± 0.11
10.95 ± 1.05
19.64 ± 2.06
0.16 ± 0.03

MQ-87
1.93 ± 0.14
10.95 ± 0.55
16.10 ± 0.87
0.04 ± 0.01

Structure 2 Compounds

MQ-47
1.10 ± 0.20
1.50 ± 0.28
6.42 ± 1.11
−0.01 ± 0.03

MQ-48
1.03 ± 0.01
1.64 ± 0.06
7.10 ± 1.51
0.01 ± 0.0

MQ-49
0.92 ± 0.01
1.02 ± 0.01
1.86 ± 0.06
0.02 ± 0.01

MQ-50
1.02 ± 0.01
1.18 ± 0.02
1.98 ± 0.07
0.0 ± 0.0

MQ-51
0.97 ± 0.03
1.02 ± 0.02
1.59 ± 0.11
0.08 ± 0.08

MQ-53
1.41 ± 0.09
8.47 ± 0.76
14.53 ± 1.38
0.12 ± 0.02

MQ-54
1.01 ± 0.05
4.03 ± 0.31
11.41 ± 1.18
0.05 ± 0.01

The GABA concentration used for the control response was 2 μM. Each compound was evaluated on at least four different oocytes at the concentrations indicated, and the results reported are the ratio of currents measured in the presence/absence of added compound. Gating represents direct current gated by 10 μM compound in the absence of GABA, and this current is reported as the ratio of compound only current/2 μM GABA current. Error limits are calculated as standard error of the mean (N≧4). Methods used are known in the art (see Jiang, X., et al.).

Tadpole Loss of Righting and Swimming

Table 3 discloses the anesthetic effects of the compounds of the present disclosure. In particular, the anesthetic effect of the compounds of the present disclosure on Loss of Righting Reflex (LRR) and Loss of Swimming Reflex (LSR).

TABLE 3

Tadpole Loss of Righting (LRR) & Loss of Swimming (LSR) EC₅₀

Values (μM) Reflexes by Analogues

Com-
Tadpole LRR
Tadpole LRR
Tadpole LSR
Tadpole LSR

pound
EC₅₀(μM)
n_Hill
EC₅₀(μM)
n_Hill

Structure 1 Compounds

MQ-31
0.43 ± 0.08
−2.91 ± 1.16
1.04 ± 0.0
−16.9 ± 0.7

MQ-32
0.36 ± 0.13
−4.97 ± 5.92
1.07 ± 0.0
−21.1 ± 1.0

MQ-33
0.24 ± 0.01
−2.65 ± 0.15
0.55 ± 0.01
−33.3 ± 0.1

MQ-36
7.90 ± 4.45
−1.57 ± 0.84
>30
—

MQ-37
0.16 ± 0.0
−2.87 ± 0.06
0.54 ± 0.01
−33.3 ± 0.1

MQ-38
0.38 ± 0.06
−4.88 ± 3.39
0.87 ± 0.0
−20.4 ± 0.5

MQ-39
0.34 ± 0.0
−19.3 ± 0.7
1.07 ± 0.0
−16.1 ± 0.9

MQ-83
2.19 ± 0.44
−1.79 ± 0.47
5.48 ± 0.12
−33.3 ± 0.1

MQ-85
0.35 ± 0.02
−2.60 ± 0.55
0.55 ± 0.01
−33.3 ± 0.1

MQ-86
0.38 ± 0.05
−4.87 ± 2.93
0.55 ± 0.01
−33.3 ± 0.1

MQ-87
0.10 ± 0.01
−20.6 ± 0.6
0.33 ± 0.0
−149 ± 0.5

Structure 2 Compounds

MQ-47
3.76 ± 5.22
−4.87 ± 28.4
None @ 10
—

MQ-48
2.39 ± 0.28
−2.10 ± 0.42
7.49 ± 0.0
−28.6 ± 0.0

MQ-49
2.40 ± 0.76
−1.71 ± 0.67
5.48 ± 0.12
−33.3 ± 0.1

MQ-50
2.01 ± 1.3
−1.30 ± 0.67
10
—

MQ-51
None @ 10
—
None @ 10
—

MQ-53
1.49 ± 0.19
−1.91 ± 0.36
3.34 ± 0.09
−16.0 ± 3.9

MQ-54
3.34 ± 0.11
−16.3 ± 5.3
5.48 ± 0.2
−33.3 ± 0.1

Methods used are known in the art (see Jiang, X., et al.). Error limits are calculated as standard error of the mean (N=10 or more animals at each of five or more different concentrations).

EQUIVALENTS AND SCOPE

In view of the above, it will be seen that the several advantages of the disclosure are achieved and other advantageous results attained. As various changes could be made in the above processes and composites without departing from the scope of the disclosure, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

When introducing elements of the present disclosure or the various versions, embodiment(s) or aspects thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. It is also noted that the terms “comprising”, “including”, “having” or “containing” are intended to be open and permits the inclusion of additional elements or steps.

Number	Name	Date	Kind
3206459	Cross	Sep 1965	A
4071625	Grunwell et al.	Jan 1978	A
4389345	Lenz	Jun 1983	A
5925630	Upasani et al.	Jul 1999	A
7781421	Covey et al.	Aug 2010	B2
20020091112	Menzenbach et al.	Jul 2002	A1
20050176976	Calogeropoulou et al.	Aug 2005	A1
20060094696	Leese et al.	May 2006	A1
20100234335	Gravanis et al.	Sep 2010	A1

Number	Date	Country
2632677	Jan 1978	DE
0104489	Apr 1984	EP
2008151745	Dec 2008	WO
2012013816	Feb 2012	WO
2012083090	Jun 2012	WO
2012116290	Aug 2012	WO

Neuroactive substituted cyclopenta[b]phenanthrenes as modulators for GABA type-A receptors

Information

Patent Number

Date Filed

Date Issued

Inventors

Original Assignees

Examiners

Agents

CPC

Field of Search

US

International Classifications

Term Extension

Abstract

Description

Claims

CROSS-REFERENCE TO RELATED APPLICATION

GOVERNMENT SUPPORT

US Referenced Citations (9)

Foreign Referenced Citations (6)

Non-Patent Literature Citations (44)

Related Publications (1)

Provisional Applications (1)

Entry
Ruzicka, et al., “Steroids and sex hormones. CXXXIX. The relation between constitution and odor of steroids. Methylandrostane and allopregnane derivatives,” Helvetica Chimica Acta, vol. 30(3), pp. 867-878 (1947), Abstract only.
Heard, et al., “Steroids. VII. Preparation of androstan-3(β)-ol-7-one from dehydroisoandrosterone,” Journal of Biological Chemistry, vol. 165, pp. 677-685, 1946, Abstract only.
Fajkos, et al., “Steroids. XXIII. Synthesis and configuration of the two stereoisomeric 3β-hydroxy-16-acetylandrostanes,” Chemicke Listy pro Vedu a Prumysl, vol. 50, pp. 791-799 (1956), Abstract only.
International Search Report and Written Opinion issued for International Application No. PCT/US2014/016405 (Jul. 16, 2014).
Cerny, et al., “Syntheses of 19-[O-(carboxymethyl)oxime] haptens of epipregnanolone and pregnanolone,” Steroids, vol. 71(2), pp. 120-128 (2006).
Cerny, et al., “Synthetic approach to 5alpha-pregnanolone 19-[O-(carboxymethyl) oxime] derivatives,” Collection of Czechoslovak Chemical Communications, vol. 69(9), pp. 1805-1817 (2004).
Wicha, et al., “Transformations of steroidal neopentyl systems. II. Migration of acetate from the 3beta- to the 19-hydroxyl in delta 5 and A/B-trans steroids,” Canadian Journal of Chemistry, vol. 45(7), pp. 707-711 (1967).
Hill, et al., “Photochemische Reaktionen. 32 Mitteilung. UV-Bestrahlung von gesattigten und beta,gamma-ungesattigten, homoallylisch konjugierten steroidaldehyden,” Helvetica Chimica Acta, vol. 49(1), pp. 292-311 (1946).
Wicha, et al., “Transformations of steroidal neopentyl systems. VII. Mechanism of the transformation of (19R)-(19)hydroxy-19-methyl-3-oxo-5alpha-to 3alpha-hydroxy-19-methyl-19-oxo-5alpha-analogs,” Journal of Organic Chemistry, vol. 38(7), pp. 1280-1283 (1973).
Wicha, et al., “Transformations of steroidal neopentyl systems. V. Synthesis and proof of the configuration of 19a-methyl-19S-alcohols,” Journal of the Chemical Society [Section] C: Organic, vol. 6, pp. 947-951 (1969).
Wicha, et al., “Transformations of steroidal neopentyl systems. IV. Stereochemistry of products of reaction of methyllithium with steroidal delta5-19-aldehydes,” Journal of the Chemical Society [Section] C: Organic, vol. 14, pp. 1740-1746 (1968).
Caspi, et al., “Stereochemistry of 19-hydroxy-19alpha-methyl steroids,” Chemical Communications, vol. 7, pp. 209-210 (1966).
Knox, et al., “Steroids. CCLXXVIII. Reductions of 19-substituted androst-4-en-3-ones and related compounds,” Journal of Organic Chemistry, vol. 30(7), pp. 2198-2205 (1965).
International Search Report and Written Opinion issued for International Application No. PCT/US2013/076214 (Jun. 5, 2014).
Anderson, et al. “Anesthetic Activity of Novel Water-Soluble 2β-Morpholinyl Steroids and Their Modulatory Effects at GABA-A Receptors,” J. Med. Chem., vol. 40, pp. 1668-1681 (1997).
Bandyopadhyaya, et al., “Neurosteroid analogues. 15. A comparative study of the anesthetic and GABAergic actions of alphaxalone, Δ 16-alphaxalone and their corresponding 17-carbonitrile analogues,” Bioorg Med Chem Lett., vol. 20, Issue 22, pp. 6680-6684 (Nov. 15, 2010).
“Pharmaceutical Salts”, Berge et al., J. Pharmaceutical Sciences, 1977, 66, 1-19.
E. Stastna, et al., Neurosteroid Analogues. 16. A New Explanation for the Lack of Anesthetic Effects in Δ16-Alphaxalone and Identification of a Δ17(20) Analogue with Potent Anesthetic Activity, J. Med. Chem., 54(11), pp. 3926-3934 (2011).
Green, P. S.; Yang, S. H.; Nilsson, K. R.; Kumar, A. S.; Covey, D. F.; Simpkins, J. W. The nonfeminizing enantiomer of 17β-estradiol exerts protective effects in neuronal cultures and a rat model of cerebral ischemia. Endocrinology 2001, 142, 400-406.
Han, et al., “Neurosteroid Analogs. 3. The Synthesis and Electrophysiological Evaluation of Benz[e]indene Congeners of Neuroactive Steroids Having the 5â-Configuration,” J. of Med. Chem., vol. 38(22), pp. 4548-4556 (1995).
Hu, Y. F.; Wittmer, L. L.; Kalkbrenner, M.; Evers, A. S.; Zorumski, C. F.; Covey, D. F. Neurosteroid analogues. Part 5. Enantiomers of neuroactive steroids and benz[e]indenes: total synthesis, electrophysiological effects on GABAA receptor function and anesthetic actions in tadpoles. J. Chem. Soc. Perkin Trans. 1 1997, 3665-3671.
International Search Report and Written Opinion for PCT/US2012/026542, dated Dec. 12, 2012, 14 pages.
Kaji, et al., “Synthesis of 3-epi-6, 7-dideoxyxestobergsterol A,” Chem. & Pharm. Bulletin, vol. 48(10), pp. 1480-1483 (2000).
Katona, B. W.; Krishnan, K.; Cai, Z. Y.; Manion, B. D.; Benz, A.; Taylor, A.; Evers, A. S.; Zorumski, C. F.; Mennerick, S.; Covey, D. F. Neurosteroid analogues. 12. Potent enhancement of GABA-mediated chloride currents at GABAA receptors by ent-androgens. Eur. J. Med. Chem. 2008, 43, 107-113.
Nilsson, K. R.; Zorumski, C. F.; Covey, D. F. Neurosteroid analogues. 6. The synthesis and GABAA receptor pharmacology of enantiomers of dehydroepiandrosterone sulfate, pregnenolone sulfate, and (3α,5β)-3-hydroxypregnan-20-one sulfate. J. Med. Chem. 1998, 41, 2604-2613.
Qian & Covey, “The efficient and enantiospecific total synthesis of cyclopenta[b]phenanthrenes structurally related to neurosteroids,” Adv. Syn. & Cata., vol. 352 (11-12), pp. 2057-2061 (2010).
Rychnovsky & Mickus, “Synthesis of ent-cholesterol, the unnatural enantiomer,” J. of Org. Chem., vol. 57(9), pp. 2732-2736 (1992).
Santaniello & Caspi, “Reduction of certain steroidal 19-sulfonic esters with metal hydrides,” J. of Ster. Biochem., vol. 7 (3), pp. 223-227 (1976).
Sarett, L.H., A new method for the preparation of 17(alpha)-hydroxy-20-ketopregnanes. J. Am. Chem. Soc., 70: 1454-8 (1948).
Scaglione, et al., “Neurosteroid Analogues. 14. Alternative Ring System Scaffolds: GABA Modulatory and Anesthetic Actions of Cyclopenta[b]phenanthrenes and Cyclopenta[b]anthracenes,” J. Med. Chem., vol. 51, pp. 1309-1318 (2008).
Shu Hong-Jin et al. Characteristics of concatemeric GABAA receptors containing α4/σ subunits expressed in Xenopus oocytes. British Journal of Pharmacology, 2012, 165, pp. 2228-2243.
Stastna, E.; Rath, N. P.; Covey, D. F. The use of symmetry in enantioselective synthesis: Four pairs of chrysene enantiomers prepared from 19-nortestosterone. Org. Biomol. Chem. 2011, 9, 4685-4694.
Upasani, et al., “3α-Hydroxy-3β-(phenylethyny1-5β-pregnan-20-ones: Synthesis and Pharmacological Activity of Neuroactive Steroids with High Affinity for GABA-A Receptors,” J. Med. Chem., vol. 40, pp. 73-84 (1997).
“A New Classification of Prodrugs: Regulatory Perspectives”, Wu, Pharmaceuticals (2009) 2:77-81.
Jiang, X., et al., Neurosteroid analogues. 9. Conformationally constrained pregnanes: structure-activity studies of 13,24-cyclo-18,21-dinorcholane analogues of the GABA modulatory and anesthetic steroids (3α,5α)-and (3α,5α)-3-hydroxypregnan-20-one. J. Med. Chem., 46: 5334-48 (2003).
Hauser, et al., “Steroids. CCV. Fragmentations and intramolecular abstractions of tertiary hydrogen atoms by primary oxy radicals with fixed reaction centers,” Helv. Chim. Acta, vol. 47, pp. 1961-1979 (1964).
Qian, et al., “Neurosteroid Analogues, 18. Structure-Activity Studies of ent-Steroid Potentiators of γ-Aminobutyric Acid Type A Receptors and Comparison of Their Activities with Those of Alphaxalone and Allopregnanolone,” J. of Med. Chem., vol. 57(1), pp. 171-190 (2014).
Ruzicka, et al., “Steroids and sex hormones. CXXXIX. The relation between constitution and odor of steroids. Methylandrostane and allopregnane derivatives,” Helvetica Chimica Acta, vol. 30, pp. 867-878 (1947).
Spiegel et al., “Use of Nonaqueous Solvents in Parenteral Products,” J. of Pharm. Sciences, vol. 52, No. 10, pp. 917-927 (1963).
Stastna, et al., “Stereoselectivity of sodium borohydride reduction of saturated steroidal ketones utilizing conditions of Luche reduction,” Steroids, vol. 75(10), pp. 721-725 (2010).