Patent Application
20100311975
The present disclosure relates to the field of catalytic reactions, in which a catalytic system comprising a cationic metal complex is used for organic chemical synthesis, for example, but not limited to the hydrogenation or reduction of compounds containing a carbon-carbon (C═C) or a carbon-heteroatom (C═O, C═N) double bond.
The catalysis approach towards synthesis offers several distinct advantages (e.g. cost savings, less waste generation) over more traditional protocols using stoichiometric reagents. In particular, transition metal (TM) catalysis has revolutionized organic synthesis (Tsuji, J. Transition Metal Reagens and Catalysts; Wiley: West Sussex, England, 2002). The near constant improvement in the field of TM catalysis is undoubtedly due in large part to the introduction of new and improved ligands, which allows for desired transformations to be carried out in a more efficient manner (i.e. milder conditions, lower catalyst loadings, higher yields and higher enantioselectivities when applicable).
Catalytic hydrogenation is one of the fundamental reactions in chemistry, and is used in a large number of chemical processes. It is now recognized that catalytic hydrogenations of carbon-carbon double bonds of alkenes, and carbon-heteroatom double bonds of ketones, aldehydes and imines are indispensable processes for the production of the wide range of alkanes, alcohols and amines, including chiral compounds, which are useful as valuable end products and precursors for the pharmaceutical, agrochemical, flavor, fragrance, material and fine chemical industries.
Amongst the several different kinds of processes known to achieve such transformation, two important types are: (a) transfer hydrogenation processes, in which hydrogen-donors such as secondary alcohols, and in particular isopropanol (iPrOH), and triethlammonium formate (HCOOH/NEt3) are used, (b) hydrogenation processes, in which molecular hydrogen is used. Both hydrogen transfer and hydrogenation processes need a catalyst or catalytic system to activate the reducing agent, such as an alcohol, HCOOH/NEt3 or molecular hydrogen.
The catalytic hydrogenation processes developed by Noyori and coworkers (Ohkuma et al., J. Am. Chem. Soc., 1995, 107, 2675 and 10417) are very attractive, since the catalysts consist of air-stable ruthenium complexes of the type RuCl2(PR3)2(diamine) and RuCl2(diphosphine)(diamine) which are precursors for the generation of what appears to be some of the most active catalysts for the homogeneous and asymmetric hydrogenation of ketones and imines in the presence of a base and hydrogen gas. It has been proposed and subsequently mechanistically elucidated that the key molecular recognition feature of these catalysts is the presence of mutually cis N—H and Ru—H moieties of the catalytic dihydride species (RuH2(PR3)2(diamine) and RuH2(diphosphine)(diamine)) that electronically bind and activate the substrate and facilitate reduction.
Other reactions for which transition metal catalysts have found significant applications include hydroformylations, hydrosilylations, hydroborations, hydroaminations, hydrovinylations, hydroarylations, hydrations, oxidations, epoxidations, reductions, C—C and C—X bond formations (includes reactions such as Heck, Suzuki-Miyaura, Negishi, Buchwald-Hartwig Amination, α-Ketone Arylation, N-Aryl Amination, Murahashi, Kumada, Negishi and Stille reactions etc.), functional group interconversions, kinetic resolutions, dynamic kinetic resolutions, cycloadditions, Diels-Alder reactions, retro-Diels-Alder reactions, sigmatropic rearrangements, electrocyclic reactions, ring-opening and/or ring-closing olefin metatheses, carbonylations, and aziridinations.
The hydrogenation of ketones has been successfully and advantageously performed using cationic salts of certain neutral Fe(II), Ru(II) and Os(II) complexes. The cationic complexes were prepared by treatment of the neutral precursors with anion abstracting agents. The resulting complexes are air and moisture stable. Solutions can be prepared and handled in air with no obvious signs of decay. The activity of the cationic complexes matches that of the neutral precursors. In several cases, the cationic derivatives give products with improved enantiomeric excess relative to the neutral congener.
Accordingly, the present disclosure provides a compound selected from a compound of Formula I, II, III, IV and V:
[M(P2)(PN)Xq(LB)n]r+[Y−]r (I)
[M(PN)2Xq(LB)n]r+[Y−]r (II)
[M(P)m(N2)Xq(LB)n]r+[Y−]r (III)
[M(PNNP)Xq(LB)n]r+[Y−]r (IV) and
[M(P2)(N2)Xq(LB)n]r+[Y−]r (V)
wherein
Also included in the present disclosure is a process for preparing a compound of the disclosure comprising combining a precursor metal compound, an anion abstracting agent, and one or more P, P2, N2, PN or PNNP ligands, and optionally a base and reacting under conditions to form the compound of the disclosure and optionally isolating the compound of the disclosure.
The present disclosure also includes a method for catalyzing a synthetic organic reaction comprising combining starting materials for the reaction with a compound according to the disclosure under conditions for performing the reaction.
The present disclosure also includes the use of a compound of the disclosure for catalyzing a synthetic organic reaction.
The synthetic organic transformations to which the compounds of the disclosure can be applied include but are not limited to: hydrogenations, transfer hydrogenations, hydroformylations, hydrosilylations, hydroborations, hydroaminations, hydrovinylations, hydroarylations, hydrations, oxidations, epoxidations, reductions, C—C and C—X bond formations (including, for example, Heck, Suzuki-Miyaura, Negishi, Buchwald-Hartwig Amination, α-Ketone Arylation, N-Aryl Amination, Murahashi, Kumada, Negishi and Stille reactions etc.), functional group interconversions, kinetic resolutions, dynamic kinetic resolutions, cycloadditions, Diels-Alder reactions, retro-Diels-Alder reactions, sigmatropic rearrangements, electrocyclic reactions, ring-openings, ring-closings, olefin metatheses, carbonylations, and aziridinations. In all transformations listed above the reactions may or may not be regioselective, chemoselective, stereoselective or diastereoselective.
In an embodiment, the present disclosure relates to a process for the reduction of compounds comprising a carbon-carbon (C═C), carbon-oxygen (C═O) or carbon-nitrogen (C═N) double bond, to the corresponding hydrogenated alkane, alcohol or amine, comprising contacting a compound comprising the C═C, C═O or C═N double bond with a catalyst of the Formula (I), (II), (III), (IV) or (V) under hydrogenation conditions.
Other features and advantages of the present disclosure will become apparent from the following detailed description. It should be understood, however, that the detailed description and the specific examples while indicating preferred embodiments of the disclosure are given by way of illustration only, since various changes and modifications within the spirit and scope of the disclosure will become apparent to those skilled in the art from this detailed description.
The present disclosure will now be described in greater detail with reference to the attached drawings in which:
The term “C1-nalkyl” as used herein means straight and/or branched chain, saturated alkyl radicals containing from one to “n” carbon atoms and includes (depending on the identity of n) methyl, ethyl, propyl, isopropyl, n-butyl, s-butyl, isobutyl, t-butyl, 2,2-dimethylbutyl, n-pentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, n-hexyl and the like, where the variable n is an integer representing the largest number of carbon atoms in the alkyl radical.
The term “C1-nalkenyl” as used herein means straight and/or branched chain, unsaturated alkyl radicals containing from one to n carbon atoms and one to three double bonds, and includes (depending on the identity of n) vinyl, allyl, 2-methylprop-1-enyl, but-1-enyl, but-2-enyl, but-3-enyl, 2-methylbut-1-enyl, 2-methylpent-1-enyl, 4-methylpent-1-enyl, 4-methylpent-2-enyl, 2-methylpent-2-enyl, 4-methylpenta-1,3-dienyl, hexen-1-yl and the like, where the variable n is an integer representing the largest number of carbon atoms in the alkenyl radical.
The term “C3-ncycloalkyl” as used herein means a monocyclic or polycyclic saturated carbocylic group containing from three to n carbon atoms and includes (depending on the identity of n), cyclopropyl, cyclobutyl, cyclopentyl, cyclodecyl, bicyclo[2.2.2]octane, bicyclo[3.1.1]heptane and the like, where the variable n is an integer representing the largest number of carbon atoms in the cycloalkyl group.
The term “aryl” as used herein means a monocyclic, bicyclic or tricyclic aromatic ring system containing at least one aromatic ring and from 6 to 14 carbon atoms and includes phenyl, naphthyl, anthracenyl, 1,2-dihydronaphthyl, 1,2,3,4-tetrahydronaphthyl, fluorenyl, indanyl, indenyl and the like.
The term “heterocyclic” as used herein means a monocyclic, bicyclic or tricyclic ring system containing from 5 to 14 atoms of which, unless otherwise specified, one, two, three, four or five are heteromoieties independently selected from N, NRa, NRbRc, O, S, SiRa and SiRbRc, wherein Ra is selected from H, C1-6alkyl, ═O and OH and Rb and Rc are independently selected from H and C1-6alkyl. When the ring system includes at least one aromatic ring it is referred to as “heteroaryl”. Heterocylic groups include, for example, thienyl, furyl, pyrrolyl, pyrididyl, indolyl, quinolyl, isoquinolyl, tetrahydroquinolyl, benzofuryl, benzothienyl and the like.
The term “halo” as used herein means halogen and includes chloro, fluoro, bromo, iodo and the like.
The term “fluoro-substituted” as used herein means that one or all of the hydrogens on the referenced group is replaced with fluorine.
The suffix “ene” added on to any of the above groups means that the group is divalent, i.e. inserted between two other groups.
The term “ring system” as used herein refers to a carbon-containing ring system, that includes monocycles, fused bicyclic and polycyclic rings, bridged rings and metalocenes. Where specified, the carbons in the rings may be substituted or replaced with heteroatoms.
The term “polycyclic” as used herein means groups that contain more than one ring linked together and includes, for example, groups that contain two (bicyclic), three (tricyclic) or four (quadracyclic) rings. The rings may be linked through a single bond, a single atom (spirocyclic) or through two atoms (fused and bridged).
The term “non-coordinating anion” as used herein refers to an anion which does not formally bond to or share electrons with the metal center in a covalent bond.
The term “joined together” as used herein means that two substituents are linked together via a linker grouping to form a ring system. The linker grouping comprises at least one atom but may also comprise several atoms, for example up to 20 atoms, resulting in the formation of monocyclic and polycyclic ring systems.
The term “compound(s) of the disclosure” means a compound of the Formula (I), (II), (III), (IV) or (V), or mixtures thereof.
In understanding the scope of the present disclosure, the term “comprising” and its derivatives, as used herein, are intended to be open ended terms that specify the presence of the stated features, elements, components, groups, integers, and/or steps, but do not exclude the presence of other unstated features, elements, components, groups, integers and/or steps. The foregoing also applies to words having similar meanings such as the terms, “including”, “having” and their derivatives. Finally, terms of degree such as “substantially”, “about” and “approximately” as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. These terms of degree should be construed as including a deviation of at least ±5% of the modified term if this deviation would not negate the meaning of the word it modifies.
Rendering the neutral metal complexes of the present disclosure into an ionic pair dramatically altered the behaviour and properties of the original metal complex. These changes may be borne out of changes in structure of the resulting complex, the charged nature of the newly formed ionic complex or they may be a result of qualities imparted by the new counter ion. Regardless of the origin of effect, there were great advantages gained from this approach in the present disclosure.
Removal of any coordinating ligand from the metal complexes of the present disclosure had the effect of introducing a vacant coordination site. In transition-metal catalysis this is often imperative for substrate binding and may indeed be rate limiting with respect to the catalytic cycle. Abstraction of one or two anionic ligands and substituting them with non- or weakly coordinating anions represents one such method for installing a vacant coordination site. In this manner, generating cationic complexes by abstraction of coordinating anionic ligands and substitution with non-coordinating anionic ligands lead to more active catalysts.
The exchange of one or two coordinating anionic ligands with non-coordinating or weakly coordinating ligands resulted in a more electrophilic, cationic metal centre. This increased electrophilicity lead to stronger binding between the metal and nucleophilic substrates. With respect to catalytic processes involving metal-substrate interactions, this has the obvious consequences and is especially beneficial in the case of weaker nucleophiles such as those with electron-withdrawing groups.
Transforming the covalent metal complexes of the present disclosure into ionic salts lead to derivatives which were more stable than their parents. Without wishing to be limited by theory, increased stability is the result of the removal of electron density from the metal leading to a metal centre which is less readily oxidized. Thus, the ionic salts prepared from neutral precursors were generally more stable to oxidation under atmospheric conditions displaying greater tolerance toward oxygen and moisture and greater storage stability (i.e. shelf-life).
The solubility properties of ionic complexes were also different from their neutral precursors. Generally, ionic complexes tended to be more soluble in polar solvents and less soluble in apolar solvents. Some ionic complexes were also more soluble in aqueous solutions. That being said, the solubility of the ionic complex can be further tuned with the selection of the anion. For instance, highly fluorinated anions tended to impart a high degree of solubility in a broad range of solvents. In fact, many ionic complexes incorporating highly fluorinated anions were more soluble in nonpolar solvents than the corresponding neutral precursor while their solubility in polar solvents remained high owing to the ionic nature of the complex.
The ability to tailor solubility also afforded the ability to control the solid properties of the ionic complex. That is, polar salts could be readily precipitated with nonpolar solvents leading to higher isolated yields and more regular and controllable particle sizes. A corollary to this property is that these ionic catalysts also hold the promise of more facile removal from product mixtures. An obvious benefit when one considers the use of ionic catalysts in applications where low residual metals are imperative.
While rendering a neutral catalyst cationic holds the promise of many critical advantages, the utility of this approach is limited by competence in catalysis of the resulting ionic complex. If the derived ionic catalyst is no longer active in catalysis then the advantages described above are obviously moot. In the present disclosure, the cationic ruthenium catalysts were shown to be excellent hydrogenation catalysts. The activity of the cationic complexes matched that of the neutral precursors and, in several cases, the cationic derivatives gave products with improved enantiomeric excess relative to the neutral congener. While not wishing to be limited by theory, this is likely due to the fact that the cationic complexes disclosed herein are more reliably and reproducibly activated prior to entering the catalytic cycle. That is to say that while all of the complexes are subject to activation, the cationic complexes fare better in this process than the neutral analogues. The activation process, which is carried out in alcohol solvents and is often irreproducible and unpredictable, is better suited to the cationic complexes since they are soluble in the solvent system while the neutral complexes are either insoluble or moderately soluble. The poor solubility of the neutral compounds means that the activation is often incomplete and can lead to side reactions giving catalytically inactive species or active species which do not retain the desired stereoselectivity.
Accordingly, the present disclosure provides a compound selected from a compound of Formula I, II, III, IV and V:
[M(P2)(PN)Xq(LB)n]r+[Y−]r (I)
[M(PN)2Xq(LB)n]r+[Y−]r (II)
[M(P)m(N2)Xq(LB)n]r+[Y−]r (III)
[M(PNNP)Xq(LB)n]r+[Y−]r (IV) and
[M(P2)(N2)Xq(LB)n]r+[Y−]r (V)
wherein
In an embodiment of the disclosure, P is a monodentate phosphine ligand of the Formula (VI):
PR1R2R3 (VI)
wherein R1, R2 and R3 are independently selected from C6-18aryl, C1-20alkyl and C3-20cycloalkyl, each being optionally substituted with one to five substituents independently selected from C1-6alkyl, fluoro-substituted C1-6alkyl, halo, C1-6alkoxy, fluoro-substituted C1-6alkoxy and C6-14aryl. In further embodiments of the disclosure, R1, R2 and R3 are independently selected from phenyl, C1-6alkyl and C3-10cycloalkyl, each being optionally substituted with one to three substituents independently selected from C1-4alkyl, fluoro-substituted C1-4alkyl, halo, C1-4alkoxy and fluoro-substituted C1-6alkoxy. In further embodiments of the disclosure, R1, R2 and R3 are all cyclohexyl, phenyl, xylyl or tolyl.
In another embodiment of the disclosure, P2 is a bidentate bisphosphino ligand of the Formula (VII):
R4R5P-Q1-PR6R7 (VII)
wherein R4, R5, R6 and R7 are, independently, as defined for R1, R2 and R3, and Q1 is selected from unsubstituted or substituted C1-C10alkylene and unsubstituted or substituted C1-C8alkenylene where the substituents on Q1 are independently selected from one or more of C1-6alkyl, fluoro-substituted C1-6alkyl, halo, C1-6alkoxy, fluoro-substituted C1-6alkoxy and unsubstituted or substituted C6-14aryl and/or two substituents on Q1 are joined together to form, including the carbon atoms to which they are attached, one or more unsubstituted or substituted 5-20-membered monocyclic, polycyclic, heterocyclic, carbocyclic, saturated, unsaturated or metallocenyl ring systems, and Q1 is chiral or achiral. In further embodiments of the disclosure, R4, R5, R6 and R7 are independently selected from phenyl, C1-6alkyl and C3-10cycloalkyl, each being optionally substituted with one to three substituents independently selected from C1-4alkyl, fluoro-substituted C1-4alkyl, halo, C1-4alkoxy and fluoro-substituted C1-4alkoxy and Q1 is selected from unsubstituted or substituted C1-C8alkylene where the substituents on Q1 are independently selected from one to four C1-4alkyl, fluoro-substituted C1-4alkyl halo, C1-4alkoxy, fluoro-substituted C1-4alkoxy, unsubstituted and substituted phenyl and substituted and unsubstituted naphthyl, or two substituents are joined together to form, including the carbon atoms to which they are attached, one or more unsubstituted or substituted phenylene, cyclohexylene, naphthylene, pyridylene or ferrocenylene groups, and Q1 is chiral or achiral. In further embodiments of the disclosure, R4, R5, R6 and R7 are all cyclohexyl, phenyl, xylyl or tolyl. Unless otherwise specified, the term substituted means that one or more, including all, but suitably one to five, of the available hydrogen atoms on a group are replaced with C1-6alkyl, fluoro-substituted C1-6alkyl, C1-6alkoxy, fluoro-substituted C1-4alkyl, halo or C6-14aryl. Representative examples of the preparation of bis(phosphino) ligands are found in Gupta, M. et al. Chem. Commun. 1996, 2083-2084; Moulton, C. J. J. Chem. Soc. Dalton, 1976, 1020-1024). Other bis(phosphino) ligands are selected from:
wherein Cy is C5-8cycloalkyl;
where Ar is phenyl (PPhos), xylyl (XylPPhos) or tolyl (TolPPhos);
where Ar is phenyl (PhanePhos), xylyl (XylPhanePhos) or tolyl (TolPhanePhos); and optical isomers thereof and mixtures of optical isomers in any ratio.
In another embodiment of the disclosure, PN is a ligand of the Formula (VIII):
R8R9P-Q2-NR10R11 (VIII)
wherein R8 and R9 are, independently as defined for R1-R3;
wherein Ar is selected from Ph, tolyl and xylyl, and optical isomers thereof and mixtures of optical isomers.
In a further embodiment of the disclosure, PNNP is a tetradentate diaminodiphosphine of the formula (IXa) or a diiminodiphosphine ligand of the Formula (IXb):
R12R13P-Q3-NR14-Q4-NR15-Q5-PR16R17 (IXa)
R12R13P-Q3=N-Q4-N=Q5-PR16R17 (IXb)
wherein R12, R13, R16 and R17 are independently as defined for R1-R3, R14 and R15 are independently as defined for R10 and R11 and Q3, Q4 and Q5 are independently as defined for Q1. In further embodiments of the disclosure, R12, R13, R16 and R17 are independently selected from phenyl, C1-6alkyl and C3-10cycloalkyl, each being optionally substituted with one to five substituents independently selected from C1-4alkyl, fluoro-substituted C1-4alkyl, halo, C1-4alkoxy and fluoro-substituted C1-6alkoxy and Q3, Q4 and Q5 are independently selected from unsubstituted or substituted C1-C8alkylene and from unsubstituted or substituted C1-C8alkenylene, where the substituents on Q3, Q4 and Q5 are independently selected from one to four C1-4alkyl, fluoro-substituted C1-4alkyl, halo, C1-6alkoxy, fluoro-substituted C1-6alkoxy, unsubstituted and substituted phenyl and substituted and unsubstituted naphthyl or two substituents are joined together to form, including the carbon atoms to which they are attached, one or more unsubstituted or substituted phenyl, cyclohexyl, naphthyl or ferrocenyl groups, and Q3, Q4 and Q5 are chiral or achiral. In further embodiments of the disclosure, R12, R13, R16 and R17 are all phenyl, tolyl or xylyl. Unless otherwise specified, the term substituted means that one or more, including all, but suitably one to five, of the available hydrogen atoms on a group are replaced with C1-6alkyl, fluoro-substituted C1-6alkyl, C1-6alkoxy, fluoro-substituted C1-6alkoxy, halo or C6-14aryl. Representative examples of the preparation of diaminodiphosphine ligands are found in Li, Y-Y. et al. 2004, 218, 153-156. Exemplary PNNP ligands include:
wherein Ar is phenyl (abbreviated as DPPcydn), tolyl (abbreviated as di(p-tolyl)PPcydn) or xylyl (abbreviated as di(3,5xylyl)PPcydn);
abbreviated as dpenPPh2N2, and each optical isomer thereof and mixtures of optical isomers.
In another embodiment of the disclosure, N2 is a bidentate diamine ligand of the Formula (X):
R18R19N-Q6-NR20R21 (X)
wherein R18, R19, R20 and R21 are independently as defined for R10 and R11 and Q6 is as defined for Q1, or one of R18 or R19 and/or R20 or R21 are joined with a substituent on Q6 to form, together with the nitrogen atom to which R18, R19, R20 or R21 is attached, a 4- to 10-membered saturated, unsaturated or aromatic, monocyclic or bicyclic, substituted or unsubstituted ring system, where if the nitrogen atom is part of aromatic ring or is bonded to an adjacent atom via a double bond, the other of R18 or R19 and/or R20 or R21 is non-existent. In embodiments of the disclosure, R18, R19, R20 and R21 are all H and Q6 is selected from unsubstituted or substituted C1-C8alkenylene where the substituents on Q6 are independently selected from one to four of C1-6alkyl, fluoro-substituted C1-6alkyl, halo, C1-6alkoxy, fluoro-substituted C1-6alkoxy and unsubstituted or substituted phenyl and/or two substituents on Q6 are joined together to form, including the carbon atoms to which they are attached, one or more unsubstituted or substituted phenyl, naphthyl or ferrocenyl ring systems, and Q6 is chiral or achiral. In a further embodiment, one of R18 or R19 or R20 or R21 are joined with a substituent on Q6 to form, together with the nitrogen atom to which R18, R19, R20 or R21 is attached, a substituted or unsubstituted pyridine ring and the other of one of R18 or R19 and/or R20 or R21 is not present. Unless otherwise specified, the term substituted means that one or more, including all, but suitably one to five, of the available hydrogen atoms on a group are replaced with C1-6alkyl, fluoro-substituted C1-6alkyl, C1-6alkoxy, fluoro-substituted C1-6alkoxy, halo or C6-14aryl. Examples of the diamine ligands include, for example, methylenediamine, ethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, 2,3-diaminobutane, 1,2-cyclopentanediamine, 1,2-cyclohexanediamine, 1,1-diphenylethylenediamine, 1,1-di(p-methoxyphenyl)ethylenediamine, 1,1-di(3,5-dimethoxyphenyl)ethylenediamine, and 1,1-dinaphthylethylenediamine. Optically active diamine compounds may be also used. Examples thereof include, for example, each optical isomer of 1,2-diphenylethylenediamine (abbreviated name: DPEN), 1,2-di(p-methoxyphenyl)ethylenediamine, 1,2-cyclohexanediamine, 1,2-cycloheptanediamine, 2,3-dimethylbutanediamine, 1-methyl-2,2-diphenylethylenediamine (abbreviated as DACH or CYDN), 1-isobutyl-2,2-diphenylethylenediamine, 1-isopropyl-2,2-diphenylethylenediamine, 1-benzyl-2,2-diphenylethylen-ediamine, 1-methyl-2,2-di(p-methoxyphenyl)ethylenediamine (abbreviated name: DAMEN), 1-isobutyl-2,2-di(p-methoxyphenyl)-ethylenediamine (abbreviated name: DAIBEN), 1-isopropyl-2,2-di(p-methoxyphenyl)ethylenediamine (abbreviated name: DAIPEN), 1-benzyl-2,2-di(p-methoxyphenyl)ethylenediamine, 1-methyl-2,2-di(3,5-dimethoxyphenyl)ethylenediamine, 1-isopropyl-2,2-di(3,5-dimethoxyphenyl)ethylenediamine, 1-isobutyl-2,2-di(3,5-dimethoxy-phenyl)ethylenediamine, 1-benzyl-2,2-di(3,5-dimethoxyphenyl)ethylenediamine, 1-methyl-2,2-dinaphthylethylenediamine, 1-isobutyl-2,2-dinaphthylethylene- diamine, 1-isopropyl-2,2-dinaphthylethylenediamine, and 1-benzyl-2,2-dinaphthylethylenediamine, and mixtures of optical isomers in any ratio. Further, optically active diamine compounds which can be used are not limited to the abovementioned optically active ethylenediamine derivatives. Optically active propanediamine, butanediamine and cyclohexanediamine derivatives may be also used. In addition, these diamine ligands may be prepared by the process starting from a-amino acids described in the literature (Burrows, C. J., et al., Tetrahedron Letters, 34(12), pp. 1905-1908 (1993)), or by a variety of processes described in the general remark (T. Le Gall, C. Mioskowski, and D. Lucet, Angew. Chem. Int. Ed., 37, pp. 2580-2627 (1998)). In another embodiment of the disclosure, N2 is the bidentate aminopyridine ligand:
wherein Re is H, C1-6alkyl, fluoro-substituted C1-6alkyl or C6-14aryl, Rf is H, halo, C1-6alkyl, fluoro-substituted-C1-6alkyl, C2-6alkenyl, C2-6alkynyl, C3-7cycloalkyl, C1-6alkoxy, fluoro-substituted-C1-6alkoxy or C6-14aryl, and including each optical isomer thereof and mixtures of optical isomers. In another embodiment, Rf is H, halo, C1-4alkyl, fluoro-substituted-C1-4alkyl, C2-4alkenyl, C2-4alkynyl, C3-7cycloalkyl, C1-4alkoxy, fluoro-substituted-C1-4alkoxy or phenyl.
In an embodiment of the disclosure, X is any suitable anionic ligand, including, but not limited to, halo, C1-6alkoxy, carboxylate, sulfonates and nitrates. Suitably X is Cl.
LB is any suitable neutral Lewis base, for example any neutral two electron donor, for example acetonitrile, DMF, pyridine, tetrahydrofuran (THF), CO, tBuCN or t-BuNC.
Y is any non-coordinating counter anion, including, but not limited to, OTf, BF4, PF6, B(C1-6alkyl)4, B(fluoro-substituted-C1-6alkyl)4 or B(C6-18aryl)4 wherein C6-18aryl is unsubstituted or substituted 1-5 times with fluoro, C1-4alkyl or fluoro-substituted C1-4alkyl. In another embodiment, Y is
wherein Rg is independently halo, C1-4alkyl, fluoro-substituted-C1-4alkyl or C6-18aryl and x and x′ are independently an integer between 1 and 4. In another embodiment, Rg is halo, suitably fluoro. In a further embodiment, Y is
wherein Rh is independently halo, C1-4alkyl, fluoro-substituted-C1-4alkyl or C6-18aryl and y and y′ are independently an integer between 1 and 6. In another embodiment, Rh is halo, suitably fluoro. In another embodiment, Y is Al(C1-6alkyl)4, Al(fluoro-substituted-C1-6alkyl)4, Al(C6-18aryl)4, Al(—O—C1-6alkyl)4, Al(—O-fluoro-substituted-C1-6alkyl)4 or Al(—O—C6-18aryl)4, wherein C6-18aryl is unsubstituted or substituted 1-5 times with halo, C1-4alkyl or fluoro-substituted C1-4alkyl. In a further embodiment, Y is a carborane or a bromocarborane anion. In another embodiment, the carborane anion is a carborane such as CB11H12. In another embodiment, the bromocarborane is a bromocarborane such as CB11H6Br6.
In a further embodiment, Y is a phosphate anion. In a further embodiment the phosphate anion is of the formula
wherein Ri and Rj are independently selected from halo, C1-4alkyl, fluoro-substituted-C1-4alkyl or C6-18aryl.
In an embodiment, the anion Y is a chiral compound and is optically pure.
In general, one or two anionic ligands bound to the neutral metal precursor is abstracted by treatment with a salt of a non-coordinating anion (i.e. one which does not formally bond to or share electrons with the metal centre in a typical covalent bond) suitably in an inert atmosphere at ambient or room temperature. This leads to the formation of a salt complex comprised of a formally cationic metal complex and the associated, non- or weakly coordinating anion(s). Exemplified below (Scheme 1, reaction 1) is the use of dichloride ruthenium precursor complexes however this methodology is easily extended to other, non-chloride and other metal-containing precursors. Indeed, any other halide precursor can be handled analogously while similar procedures can be employed for non-halide precursors such as carboxylates, sulfonates, nitrates etc. Exposure of the resulting cationic complexes to coordinating Lewis Bases, either during the anion abstraction/metathesis reaction or by treatment of the isolated salts, leads to the formation of a coordinatively-saturated metal adduct. In an embodiment, after formation of the cationic catalysts, adducts are formed by the addition of co-ordinating Lewis Bases. This is described in general terms below in reaction 2. The corresponding dicationic complexes (i.e. where both anionic ligands are removed) function in a similar manner.
In another embodiment, the formation of the compounds of the disclosure is via a procedure wherein a precursor to the neutral complexes, is first rendered cationic or dicationic by treatment with one or two equivalents of a salt of a non-coordinating anion and then treated with the appropriate ligand to generate the compounds of the disclosure. Also, a one-pot procedure can also be envisioned where all of the components are combined to generate the cationic transition-metal complexes.
Accordingly, the present disclosure further includes a process for preparing a compound of the disclosure comprising combining a compound of the formula
M(P2)(PN)X2 (XI)
M(PN)2X2 (XII)
M(P)m(N2)X2 (XIII)
M(PNNP)X2 (XIV) or
M(P2)(N2)X2 (XV)
wherein M, P2, PN, P, PNNP, P2 and X are as defined above, with one or two molar equivalents of an anion abstracting agent and optionally a non- or weakly-coordinating Lewis Base, and reacting under conditions to form the compound of the disclosure and optionally isolating the compound of the disclosure.
In a further embodiment of the present disclosure, there is included a process for preparing a compound of the disclosure comprising combining a precursor metal compound with one or two molar equivalents of an anion abstracting agent, and optionally a Lewis Base and reacting under conditions to form a cationic or dicationic precursor metal compound and combining the cationic or dicationic precursor metal compound with one or more P, P2, N2, PN, or PNNP ligands, as defined above, under conditions to form the compound of the disclosure and optionally isolating the compound of the disclosure.
In an embodiment of the disclosure, the precursor metal compound is of the formula [MX2(p-ligand)]2 or MX2(ligand) wherein M and X are as defined for the compounds of the disclosure and ligand is any displaceable ligand, for example, p-cymene, benzene, cyclooctadiene (COD) or norbornadiene (NBD), suitably p-cymene or norbornadiene (NBD), for example [MCl2(p-cymene)]2 or [MCl2(NBD)]n wherein M is a metal selected from Fe, Ru and Os, in particular ruthenium.
In another embodiment of the disclosure, the precursor metal compound is of the formula MX2(P2)(LB)n, wherein M, X, P2 and LB are as defined above and n is 1 or 2. In an embodiment, the precursor metal compound is readily converted into its cationic counterparts [MX(P2)(LB)n]Y or [M(P2)(LB)n]Y2, by treatment with one or two molar equivalents of an anion abstracting agent as defined above. The corresponding cation is an air stable solid which is isolated in high yields and stored under ambient conditions. A cationic compound of the formula [MX(P2)(LB)n]Y or [M(P2)(LB)n]Y2 is readily converted into the cationic catalysts of the present disclosure, for example, by reaction with one or more P2, N2 or PN ligands, as defined above. In an embodiment, (P2) is BINAP and LB is DMF or pyridine. Metal-diphosphine-DMF complexes have been reported in the literature (Noyori et al. Tetrahedron Lett. 1991, 32:4163).
In another embodiment, the anion abstracting agent is a salt of a non-coordinating counter anion Y as defined above. In yet another embodiment, the ligands are selected from one or more of a compound of the Formula (VI), (VII), (VIII), (IX) and (X) as defined above. In another embodiment, the conditions to form the compound of the disclosure comprise reacting at a temperature of about 20° C. to about 200° C., suitably about 50° C. to about 100° C. in a suitable solvent, for about 30 minutes to 48 hours, following by cooling to room temperature. In an embodiment of the disclosure, the compound of the disclosure is isolated using standard techniques, such as by filtration, evaporation of the solvent, recrystallization and/or chromatography, to provide the compound of Formula (I), (II), (III), (IV) or (V).
The compounds of the present disclosure are useful as catalysts in organic synthesis transformations. Accordingly, the present disclosure also includes a method for catalyzing a synthetic organic reaction comprising combining starting materials for the reaction with a compound according to the disclosure under conditions for performing the reaction.
The present disclosure also includes the use of a compound of the disclosure for catalyzing a synthetic organic reaction.
In an embodiment of the disclosure, the synthetic organic reaction is selected from hydrogenation, transfer hydrogenation, hydroformylation, hydrosilylation, hydroboration, hydroamination, hydrovinylation, hydroarylation, hydration, oxidation, epoxidation, reduction, C—C and C—X bond formation (including for example, Heck, Suzuki-Miyaura, Negishi, Buchwald-Hartwig Amination, α-Ketone Arylation, N-Aryl Amination, Murahashi, Kumada, Negishi and Stille reactions), functional group interconversion, kinetic resolution, dynamic kinetic resolution, cycloaddition, Diels-Alder, retro-Diels-Alder, sigmatropic rearrangement, electrocyclic reactiona, ring-opening and/or ring-closing olefin metathesis, carbonylation and aziridination. The reaction conditions for these synthetic transformation are well known to those skilled in the art.
In one particular embodiment of the present disclosure, the compounds of the present disclosure are competent hydrogenation (including transfer hydrogenation) catalysts (as can be seen from the tables of experimental data included herein). The complexes are air and moisture stable. Solutions can be prepared and handled in air with no obvious signs of decay. The activity of the cationic complexes matches that of the neutral precursors. In several cases, the cationic derivatives give products with improved enantiomeric excess relative to the neutral congener (compare entry 27 to 28 and 29 and entry 30 to 31 and 32 in Table 1). While not wishing to be limited by theory, this is likely due to the fact that the cationic complexes disclosed herein are more reliably and reproducibly activated prior to entering the catalytic cycle. That is to say that while all of the complexes are subject to activation, the cationic complexes fare better in this process than the neutral analogues. The activation process, which is carried out in alcohol solvents and is often irreproducible and unpredictable, is better suited to the cationic complexes since they are soluble in the solvent system while the neutral complexes less so. The poor solubility of the neutral compounds means that the activation is often incomplete and can lead to side reactions giving catalytically inactive species or active species which do not retain the desired stereoselectivity.
An interesting result to come out of the derivatization to charged species is in the ligand rearrangement observed in the solid state structure of [RuCl(pyridine)(R-binap)(R,R-cydn)]BF4 (vide infra). The X-ray crystal structure of this compound shows that one of the P atoms of the BINAP ligand is trans to the coordinated pyridine ligand (
Accordingly, the present disclosure relates to a process for the reduction of compounds comprising a carbon-carbon (C═C), carbon-oxygen (C═O) or carbon-nitrogen (C═N) double bond, to the corresponding hydrogenated alkane, alcohol or amine, comprising contacting a compound comprising the C═C, C═O or C═N double bond with a catalyst of the Formula (I), (II), (III), (IV) or (V) under hydrogenation conditions.
The compound comprising a C═C, C═O or C═N, includes compounds having one or more C═C, C═O and/or C═N bonds.
In an embodiment of the invention, the compound comprising a carbon-oxygen (C═O) or carbon-nitrogen (C═N) double bond is a compound of Formula (XI):
wherein,
Reduction of compounds of Formula (XI) using a compound of the disclosure according to the process described above provides the corresponding hydrogenated compounds of Formula (XII):
wherein Z, R22 and R23 are defined as in Formula (XII).
Since R22 and R23 may be different, it is hereby understood that the final product of Formula (XII), may be chiral, thus possibly consisting of a practically pure enantiomer or of a mixture of stereoisomers, depending on the nature of the catalyst used in the process.
In an embodiment of the disclosure, the hydrogenation conditions characterizing the above process may comprise a base. Said base can be the substrate itself, if the latter is basic, or any conventional base. One can cite, as non-limiting examples, organic non-coordinating bases such as DBU, an alkaline or alkaline-earth metal carbonate, a carboxylate salt such as sodium or potassium acetate, or an alcoholate or hydroxide salt. In an embodiment of the disclosure, the bases are the alcoholate or hydroxide salts selected from the group consisting of the compounds of formula (R30O)2M′ and R30OM″, wherein M′ is an alkaline-earth metal, M″ is an alkaline metal and R30 stands for hydrogen or a linear or branched C1-20alkyl group.
Standard hydrogenation conditions, as used herein, typically implies the mixture of the substrate with a metal complex of Formula (I), (II), (III), (IV) or (V) with or without a base, possibly in the presence of a solvent, and then treating such a mixture with a hydrogen donor solvent at a chosen pressure and temperature (transfer hydrogenation) or in an atmosphere of hydrogen gas at a chosen pressure and temperature. Varying the reaction conditions, including for example, temperature, pressure, solvent and reagent ratios, to optimize the yield of the desired product would be well within the abilities of a person skilled in the art.
The following non-limiting examples are illustrative of the present disclosure:
The disclosure will now be described in further details by way of the following examples, wherein the temperatures are indicated in degrees centigrade and the abbreviations have the usual meaning in the art. All the procedures described hereafter have been carried out under an inert atmosphere unless stated otherwise. All preparations and manipulations were carried out under H2, N2 or Ar atmospheres with the use of standard Schlenk, vacuum line and glove box techniques in dry, oxygen-free solvents. Tetrahydrofuran (THF), diethyl ether (Et2O), methylene chloride and hexanes were obtained using an IT solvent purification system. Deuterated solvents were degassed and dried over activated molecular sieves. NMR spectra were recorded on a 300 MHz spectrometer (300 MHz for 1H, 75 MHz for 13C and 121.5 for 31P). All 31P chemical shifts were measured relative to 85% H3PO4 as an external reference. 1H and 13C chemical shifts were measured relative to partially deuterated solvent peaks but are reported relative to tetramethylsilane.
In an Ar filled flask, 0.25 g (0.041 mmol) [RuCl2(p-cymene)]2 and 0.16 g (0.082 mmol) of AgBF4 were combined. CH2Cl2 (10 mL) was added and the resulting orange suspension was left to stir at ambient temperature. Within several minutes the suspension darkened to brown/green in colour. After 2 hours, the suspension was filtered through Celite and the orange filtrate was reduced to approximately 1 mL in volume. Addition of hexane afforded an oily orange solid which was washed repeatedly with hexane and dried in vacuo. Yield: 0.215 g (74%).
In an Ar filled flask, 0.600 g (0.66 mmol) of RuCl2(R-binap)(R,R-cydn) and 0.129 g (0.66 mmol) of AgBF4 were combined. CH2Cl2 (15 mL) was added and the resulting rust coloured suspension was left to stir at ambient temperature for two hours after which time it was filtered, in air, through Celite. The orange filtrate was reduced to dryness leaving an orange residue. Yield: 0.620 g (97%). 31P NMR (ppm, CDCl3): 7.53 (d, JPP=45 Hz), 67.5 (d, JPP=45 Hz).
In an Ar filled flask, 0.766 g (0.73 mmol) of RuCl2(R-binap)(Ph2PCH2CH2NH2) and 0.143 g (0.73 mmol) of AgBF4 were combined. CH2Cl2 (15 mL) was added and the resulting dark orange suspension was left to stir at ambient temperature for two hours after which time it was filtered, in air, through Celite. The dark orange filtrate was reduced to dryness leaving a deep orange residue. Yield: 0.790 g (98%). 31P NMR (ppm, CDCl3): 32.6 (dd, JPP=31 Hz, JPP=24 Hz), 48.0 (dd, JPP=34 Hz, JPP=31 Hz), 62.7 (dd, JPP=34 Hz, JPP=24 Hz).
In an Ar filled flask, 0.750 g (1.19 mmol) of RuCl2(Ph2PCH2CH2NH2)2 and 0.232 g (1.19 mmol) of AgBF4 were combined. CH2Cl2 (15 mL) was added and the resulting red suspension was left to stir at ambient temperature for two hours after which time it was filtered, in air, through Celite. The dark red filtrate was reduced to dryness leaving a deep red residue. Yield: 0.790 g (97%). 31P NMR (ppm, acetone-D6): 55.0 (d, JPP=36 Hz), 73.3 (d, JPP=36 Hz).
In an Ar filled flask, 0.150 g (0.16 mmol) of [RuCl(R-binap)(R,R-cydn)]BF4 was dissolved in 6 mL of CH2Cl2 and 41 mL (0.78 mmol) of MeCN was added and the brown solution was left to stir. After 16 hours the solution had changed to pale green in colour. Removal of an aliquot for subsequent 31P NMR analysis showed that no starting material remained. Concentration of the solvent to approximately 1 mL followed by the addition of hexane (10 mL) afforded a pale green solid. The solid was filtered off, washed with hexane (2×5 mL) and dried in vacuo. Yield: 0.127 g (81%). NMR analysis of the isolated solid revealed the presence of several isomeric species, the major constituent accounting for 80% of the integrated intensity. NMR data are given only for the major isomer. 31P NMR (ppm, CDCl3): 46.3 (d, JPP=34 Hz), 48.8 (d, JPP=34 Hz).
In an Ar filled flask, 0.150 g (0.16 mmol) of [RuCl(R-binap)(R,R-cydn)]BF4 was dissolved in 6 mL of CH2Cl2 and 63 mL (0.78 mmol) of pyridine was added and the brown solution was left to stir. After 16 hours the solution had changed to yellow in colour. Removal of an aliquot for subsequent 31P NMR analysis showed that no starting material remained. Concentration of the solvent to approximately 1 mL followed by the addition of hexane (10 mL) afforded a yellow solid. The solid was filtered off, washed with hexane (2×5 mL) and dried in vacuo Yield: 0.152 g (94%). NMR analysis of the isolated solid revealed two complexes; one identified as the desired product (NMR data given below) and the other as starting material (see above). The two compounds were present in approximately equal amounts. It is unclear if a single product is isolated and dissociation of bound pyridine occurs upon dissolution or if reversion to starting material occurs during isolation. 31P NMR (ppm, CDCl3): 55.2 (d, JPP=37 Hz), 49.4 (d, JPP=37 Hz).
In an Ar filled flask, 0.150 g (0.13 mmol) of RuCl2(R-binap)(S,S-Ph2PCH(Ph)CH(Ph)NH2) and 0.025 g (0.13 mmol) of AgBF4 were combined. CH2Cl2 (6 mL) was added and the resulting green suspension was left to stir at ambient temperature for sixteen hours over which time it changed to brown in colour. The suspension was filtered, in air, through Celite and the brown filtrate was reduced to dryness leaving a brown residue. Yield: 0.108 g (69%). 31P NMR (ppm, CD2Cl2): 34.5 (pseudo t, JPP=27 Hz), 44.5 (dd, JPP=31 Hz, JPP=28 Hz), 83.9 (dd, JPP=31 Hz, JPP=26 Hz).
In an Ar filled flask, 0.150 g (0.13 mmol) of RuCl2(S-binap)(S,S-Ph2PCH(Ph)CH(Ph)NH2) and 0.025 g (0.13 mmol) of AgBF4 were combined. CH2Cl2 (6 mL) was added and the resulting green suspension was left to stir at ambient temperature for sixteen hours over which time it changed to brown in colour. The suspension was filtered, in air, through Celite and the brown filtrate was reduced to dryness leaving a brown residue. Yield: 0.096 g (61%). 31P NMR (ppm, CD2Cl2): 26.7 (dd, JPP=27 Hz, JPP=20 Hz), 48.5 (dd, JPP=33 Hz, JPP=27 Hz), 86.3 (dd, JPP=33 Hz, JPP=20 Hz).
In an Ar filled flask, 0.200 g (0.22 mmol) of RuCl2(R-binap)(R,R-cydn) and 0.192 g (0.22 mmol) of [Li(OEt2)2.5][B(C6F5)4] were combined. CH2Cl2 (10 mL) was added and the resulting dark orange suspension was left to stir at ambient temperature for 16 hours after which time it was filtered, in air, through Celite. The orange filtrate was reduced to dryness leaving an orange residue. Yield: 0.247 g (72%). 31P NMR (ppm, CDCl3): 13.1 (d, JPP=46 Hz), 72.6 (d, JPP=46 Hz).
In an Ar filled flask, 0.200 g (0.20 mmol) of RuCl2(R-binap)(Ph2PCH2CH2NH2) and 0.170 g (0.20 mmol) of [Li(OEt2)25][B(C6F5)4] were combined. CH2Cl2 (10 mL) was added and the resulting dark orange suspension was left to stir at ambient temperature for sixteen hours after which time it was filtered, in air, through Celite. The dark orange filtrate was reduced to dryness leaving a deep orange residue. Yield: 0.273 g (84%). 31P NMR (ppm, CD2Cl2): 31.3 (dd, JPP=31 Hz, JPP=24 Hz), 48.0 (dd, JPP=35 Hz, JPP=31 Hz), 62.2 (dd, JPP=35 Hz, JPP=24 Hz).
In an Ar filled flask, 0.200 g (0.32 mmol) of RuCl2(Ph2PCH2CH2NH2)2 and 0.276 g (0.32 mmol) of [Li(OEt2)2.5][B(C6F5)4] were combined. CH2Cl2 (10 mL) was added and the resulting orange suspension was left to stir at ambient temperature for sixteen hours after which time it was filtered, in air, through Celite. The orange filtrate was reduced to dryness leaving a deep orange residue. Yield: 0.273 g (86%). 31P NMR (ppm, acetone-D6): 54.9 (d, JPP=36 Hz), 72.7 (d, JPP=36 Hz).
In an Ar filled flask, 0.150 g (0.13 mmol) of RuCl2(R-tolbinap)(R,R-Ph2PCH(Ph)CH(Me)NH2) and 0.025 g (0.13 mmol) of AgBF4 were combined. CH2Cl2 (10 mL) was added and the resulting brown suspension was left to stir at ambient temperature for 2 hours. The suspension was then filtered, in air, through Celite and the brown filtrate was reduced to dryness leaving a brown residue. Yield: 0.112 g (72%). 31P NMR (ppm, CD2Cl2): 25.3 (br m), 48.6 (br t, JPP=30 Hz), 87.6 (dd, JPP=30 Hz, JPP=20 Hz).
In an Ar filled flask, 0.100 g (0.085 mmol) of RuCl2(R-tolbinap)(R,R-Ph2PCH(Ph)CH(Me)NH2) and 0.074 g (0.085 mmol) of [Li(OEt2)25][B(C6F5)4] were combined. CH2Cl2 (10 mL) was added and the resulting brown suspension was left to stir at ambient temperature for 2 hours. The suspension was then filtered, in air, through Celite and the brown filtrate was reduced to dryness leaving a brown residue. Yield: 0.123 g (79%). 31P NMR (ppm, CD2Cl2): 25.3 (br m), 48.4 (br t, JPP=30 Hz), 87.7 (dd, JPP=30 Hz, JPP=20 Hz).
31P NMR (ppm, CD2Cl2): 31.6 (br m), 46.3 (br t, JPP=32 Hz), 89.4 (br m).
31P NMR (ppm, CD2Cl2): 31.6 (br m), 46.3 (br m), 89.4 (dd, JPP=33 Hz, JPP=28 Hz).
31P NMR (ppm, CD2Cl2): 14.2 (br), 38.4 (br m), 56.6 (br m).
31P NMR (ppm, CD2Cl2): 38.8 (d, JPP=27 Hz), 41.0 (br), 55.4 (d, JPP=27 Hz).
31P NMR (ppm, CD2Cl2): 42.4 (br m), 54.5 (br).
31P NMR (ppm, CD2Cl2): No resolved peaks at ambient temperature.
31P NMR (ppm, CD2Cl2): 42.7 (br m), 55.1 (br m).
31P NMR (ppm, CD2Cl2): 44.0 (br), 68.0 (br).
31P NMR (ppm, CD2Cl2): Several broadened peaks between 10 and 70 ppm.
31P NMR (ppm, CD2Cl2): Several broadened peaks between 10 and 70 ppm.
31P NMR (ppm, CD2Cl2): Several broadened peaks between 10 and 70 ppm.
31P NMR (ppm, CD2Cl2): Several broadened peaks between 10 and 70 ppm.
31P NMR (ppm, CD2Cl2): Several broadened peaks between 10 and 70 ppm.
31P NMR (ppm, CD2Cl2): Several broadened peaks between 10 and 70 ppm.
31P NMR (ppm, CD2Cl2): Several broadened peaks between 40 and 65 ppm.
31P NMR (ppm, CD2Cl2): Several broadened peaks between 40 and 75 ppm.
31P NMR (ppm, CD2Cl2): Several broadened peaks between 40 and 65 ppm.
31P NMR (ppm, CD2Cl2): Several broadened peaks between 40 and 75 ppm.
31P NMR (ppm, CD2Cl2): Several broadened peaks between 40 and 65 ppm.
31P NMR (ppm, CD2Cl2): Several broadened peaks between −20 and 70 ppm.
In an Ar filled flask, 0.280 g (0.31 mmol) of RuCl2(R-binap)(R,R-dach) and 0.078 g (0.31 mmol) of AgPF6 were combined. CH2Cl2 (15 mL) was added and the resulting brown coloured suspension was left to stir at ambient temperature for 24 hours after which time it was filtered, in air, through a 0.45 mm PTFE syringe filter. The orange filtrate was reduced to dryness leaving an orange residue. Yield: 0.280 g (89%). 31P{1H} NMR (ppm, CDCl3): 7.53 (d, 2JPP=45 Hz), 67.5 (d, 2JPP=45 Hz), 208.6 (septuplet, 2JPF=710 Hz). **R,R-dach=R,R-cydn(hh)[(R-binap)RuCl(R,R-dach)]OTf.
In an Ar filled flask, 0.100 g (0.11 mmol) of RuCl2(R-binap)(R,R-dach) and 0.028 g (0.11 mmol) of AgOTf were combined. CH2Cl2 (5 mL) was added and the resulting rust coloured suspension was left to stir at ambient temperature for 2 hours after which time it was filtered, in air, through a 0.45 mm PTFE syringe filter. The orange filtrate was reduced to dryness leaving an orange residue. Yield: 0.065 g (58%). 31P{1H} NMR (ppm, CDCl3): 7.53 (d, 2JPP=45 Hz), 67.5 (d, 2JPP=45 Hz).). **R,R-dach =R,R-cydn
In an Ar filled flask, 0.100 g (0.11 mmol) of RuCl2(R-binap)(R,R-dach), 0.097 g (0.11 mmol) of Na[B(3,5-(CF3)2C6H3)4] and 21 mg (0.11 mmol) of AgBF4 were combined. CDCl3 (2 mL) was added and the resulting rust coloured suspension was left to stir at ambient temperature for 18 hours after which time it was filtered, in air, through a 0.45 mm PTFE syringe filter. The orange filtrate was reduced to dryness leaving a yellow-orange residue. Yield: 0.115 g (61%). 31P{1H} NMR (ppm, CDCl3): 7.73 (d, 2JPP=45 Hz), 67.2 (d, 2JPP=45 Hz)). **R,R-dach=R,R-cydn
In an Ar filled flask, 0.075 g (0.074 mmol) of RuCl2(R-binap)(Ph2PCH2CH2NH2) and 0.019 g (0.074 mmol) of AgPF6 were combined. CH2Cl2 (5 mL) was added and the resulting dark orange suspension was left to stir at ambient temperature for 24 hours after which time it was filtered, in air, through a 0.45 mm PTFE syringe filter. The dark brown-orange filtrate was reduced to dryness leaving a brown residue. Yield: 0.032 g (39%). 31P{1H} NMR (ppm, CDCl3): 32.6 (dd, 2JPP=31 Hz, 2JPP=24 Hz), 48.0 (dd, 2JPP=34 Hz, 2JPP=31 Hz), 62.7 (dd, 2JPP=34 Hz, 2JPP=24 Hz). There is also formation of another unidentified AB signal in 31P NMR: 15.3 (d, 2JPP=17 Hz), 17.3 (d, 2JPP=17 Hz). **PGly=Ph2PCH2CH2NH2
In an Ar filled flask, 0.08 g (0.078 mmol) of RuCl2(R-binap)(Ph2PCH2CH2NH2), 0.069 g (0.078 mmol) of Na[B(3,5-(CF3)2C6H3)4] and 15 mg (0.078 mmol) of AgBF4 were combined. CH2Cl2 (2 mL) was added and the resulting rust coloured suspension was left to stir at ambient temperature for 18 hours after which time it was filtered, in air, through a 0.45 mm PTFE syringe filter. The orange filtrate was reduced to dryness leaving a yellow-orange residue. Yield: 0.090 g (63%). 31P{1H} NMR (ppm, CDCl3): 7.73 (d, 2JPP=45 Hz), 67.2 (d, 2JPP=45 Hz). **PGly=Ph2PCH2CH2NH2
In an Ar filled flask, 0.150 g (0.15 mmol) of RuCl2(R-binap)(PGly) and 0.038 g (0.15 mmol) of AgOTf were combined. CH2Cl2 (5 mL) was added and the resulting dark brown suspension was left to stir at ambient temperature for 24 hours after which time it was filtered, in air, through a 0.45 mm PTFE syringe filter. The dark brown filtrate was reduced to dryness leaving a brown-yellow residue. Yield: 0.130 g (78%). 31P{1H} NMR (ppm, CDCl3): 29.4 (t, 2JPP=27 Hz), 45.8 (dd, 2JPP=33 Hz), 60.5 (t, 2JPP=27 Hz). There is also formation of another unidentified AB signal in 31P NMR: 13.4 (d, 2JPP=17 Hz), 15.4 (d, 2JPP=17 Hz). **PGly=Ph2PCH2CH2NH2
In an Ar filled flask, 0.075 g (0.12 mmol) of RuCl2(PGly)2 and 0.030 g (0.12 mmol) of AgPF6 were combined. CH2Cl2 (5 mL) was added and the resulting brown suspension was left to stir at ambient temperature for 24 hours after which time it was filtered, in air, through a 0.45 mm PTFE syringe filter. The dark orange filtrate was reduced to dryness leaving a yellow brown residue. Yield: 0.030 g (35%). 31P{1H} NMR (ppm, CDCl3): 7 different doublets in the range 52-73 ppm. **PGly=Ph2PCH2CH2NH2
In an Ar filled flask, 0.150 g (0.24 mmol) of RuCl2(PGly)2 and 0.061 g (0.24 mmol) of AgPF6 were combined. CH2Cl2 (10 mL) was added and the resulting brown suspension was left to stir at ambient temperature for 24 hours after which time it was filtered, in air, through a 0.45 mm PTFE syringe filter. The dark yellow brown filtrate was reduced to dryness leaving an orange residue. Yield: 0.095 g (53%). 31P{1H} NMR (ppm, CDCl3): 7 different doublets in the range 52-73 ppm. **PGly=Ph2PCH2CH2NH2
In an Ar filled flask, 0.08 g (0.13 mmol) of RuCl2(PGly)2, 0.112 g (0.13 mmol) of Na[B(3,5-(CF3)2C6H3)4] and 25 mg (0.13 mmol) of AgBF4 were combined. CH2Cl2 (2 mL) was added and the resulting rust coloured suspension was left to stir at ambient temperature for 18 hours after which time it was filtered, in air, through a 0.45 mm PTFE syringe filter. The orange filtrate was reduced to dryness leaving an orange residue. Yield: 0.030 g (16%). 6 different doublets in the range 30-51 ppm. **PGly=Ph2PCH2CH2NH2
In an Ar filled flask, 0.100 g (0.10 mmol) of RuCl2(S-PhanePhos)(R,R-DPEN) and 0.020 g (0.10 mmol) of AgBF4 were combined. CH2Cl2 (5 mL) was added and the resulting brown suspension was left to stir at ambient temperature for sixteen hours. The suspension was filtered, in air, through Celite and the brown filtrate was reduced to dryness leaving a brown residue. Yield: 0.048 g (46%). 31P NMR (ppm, CD2Cl2): 52.0 (d, JPP=28 Hz), 43.1 (d, JPP=28 Hz).
In an Ar filled flask, 0.050 g (0.06 mmol) of RuCl2(S-PhanePhos)(R,R-DPEN) and 0.045 g (0.06 mmol) of Li(OEt2)2.5[B(C6F5)4] were combined. CH2Cl2 (5 mL) was added and the resulting brown suspension was left to stir at ambient temperature for sixteen hours. The suspension was filtered, in air, through Celite and the brown filtrate was reduced to dryness leaving a brown residue. Yield: 0.036 g (40%). 31P NMR (ppm, CD2Cl2): 50.5 (d, JPP=28 Hz), 42.4 (d, JPP=28 Hz).
In an Ar filled flask, 0.100 g (0.10 mmol) of RuCl2(S-XylylPhanePhos)(R,R-DPEN) and 0.018 g (0.10 mmol) of AgBF4 were combined. CH2Cl2 (5 mL) was added and the resulting brown suspension was left to stir at ambient temperature for sixteen hours. The suspension was filtered, in air, through Celite and the brown filtrate was reduced to dryness leaving a brown residue. Yield: 0.066 g (63%). 31P NMR (ppm, CD2Cl2): 52 (d, JPP=28 Hz), 42 (d, JPP=28 Hz).
In an Ar filled flask, 0.050 g (0.05 mmol) of RuCl2(S-PhanePhos)(R,R-DPEN) and 0.041 g (0.05 mmol) of Li(OEt2)25[B(C6F5)4] were combined. CH2Cl2 (5 mL) was added and the resulting brown suspension was left to stir at ambient temperature for sixteen hours. The suspension was filtered, in air, through Celite and the brown filtrate was reduced to dryness leaving a brown residue. Yield: 0.065 g (81%). 31P NMR (ppm, CD2Cl2): 52.2 (d, JPP=29 Hz), 41.5 (d, JPP=29 Hz).
In an Ar filled flask, 0.100 g (0.12 mmol) of RuCl2(PPh3)2((S)-1-(pyridin-2-yl)ethanamine) and 0.024 g (0.12 mmol) of AgBF4 were combined. CH2Cl2 (5 mL) was added and the resulting brown suspension was left to stir at ambient temperature for two hours. The suspension was filtered through a 0.45 μm PTFE syringe filter and the brown filtrate was reduced to dryness leaving a brown residue. Yield: 0.070 g (66%). 19F NMR (282 MHz, CD2Cl2): −152 (s).
In an Ar filled flask, 0.150 g (0.14 mmol) of RuCl2(S-XylylPPhos)((S)-1-(pyridin-2-yl)ethanamine) and 0.027 g (0.14 mmol) of AgBF4 were combined. CH2Cl2 (5 mL) was added and the resulting brown suspension was left to stir at ambient temperature for two hours. The suspension was filtered through a 0.45 μm PTFE syringe filter and the brown filtrate was reduced to dryness leaving a brown residue. Yield: 0.127 g (81%). 19F NMR (282 MHz, CD2Cl2): −152 (s).
In an Ar filled flask, 0.150 g (0.16 mmol) of RuCl2(R-BINAP)((S)-1-(pyridin-2-yl)ethanamine) and 0.032 g (0.16 mmol) of AgBF4 were combined. CH2Cl2 (5 mL) was added and the resulting brown suspension was left to stir at ambient temperature for two hours. The suspension was filtered through a 0.45 μm PTFE syringe filter and the brown filtrate was reduced to dryness leaving a brown residue. Yield: 0.087 g (55%). 31P NMR (ppm, CD2Cl2): No resolved peaks at ambient temperature. 19F NMR (282 MHz, CD2Cl2): −152 (s).
In an Ar filled flask, 0.075 g (0.08 mmol) of RuCl2(SC,RP-PCy2-CH(CH3)-Fc-PCy2)((S)-1-(pyridin-2-yl)ethanamine) and 0.016 g (0.08 mmol) of AgBF4 were combined. CH2Cl2 (5 mL) was added and the resulting brown suspension was left to stir at ambient temperature for two hours. The suspension was filtered through a 0.45 μM PTFE syringe filter and the brown filtrate was reduced to dryness leaving a brown residue. Yield: 0.079 g (63%). 19F NMR (282 MHz, CD2Cl2): −152 (s).
In the dry box, RuCl2(Binap)(cydn) (0.18 g, 0.19 mmol) was dissolved in CH2Cl2 and Ag(CB11H12) (50 mg, 0.19 mmol) was dissolved in benzene and CH2Cl2. The two portions were then mixed and stirred for half hour. The AgCl then formed was filtered off and the compound was recrystallized from hexanes. Yield: 0.15 g, 74%.
In the dry box, RuCl2(Binap)(cydn) (12.5 mg, 0.014 mmol) was dissolved in CH2Cl2 and Ag(CB11H6Br6) (10 mg, 0.014 mmol) was dissolved in benzene and CH2Cl2. The two portions were then mixed and stirred for half hour. The AgCl then formed was filtered off and the compound was recrystallized from hexanes. Yield: 15 mg, 73%.
In the syntheses described above, the neutral precursor complexes were treated with anion abstracting agents to render the complexes cationic. The neutral precursors were generally derived from the ubiquitous ruthenium compounds [RuCl2(p-cymene)]2, [RuCl2(benzene)]2 or [RuCl2(cod)]n (cod=cyclooctadiene). These are common synthons used to prepare a range of ruthenium complexes and are known to be notoriously insoluble materials. As a result of the insolubility of these complexes, the preparation of Ru derivatives from these material require long reaction times and forcing conditions.
An alternate route to the same cationic ruthenium hydrogenation catalysts exists in the use of a cationic Ru precursor. Indeed, a cationic derivative of [RuCl2(p-cymene)]2 holds the promise of improved solubility and thus shorter reaction times and less forcing conditions. To this end, the reaction of [RuCl2(p-cymene)]2 with anion abstracting agents was explored and found to yield the desired cationic synthon according to Scheme 2 below. The complexes [Ru2Cl3(p-cymene)2][PF6] and [Ru(MeCN)3(p-cymene)]2[BF4]2 were described by Bennett et al., J. C. S. Dalton Trans. 1974, 233. Limited synthetic and spectroscopic details were provided in this report.
In an Ar filled flask, 0.25 g (0.041 mmol) [RuCl2(p-cymene)]2 and 0.16 g (0.082 mmol) of AgBF4 were combined. CH2Cl2 (10 mL) was added and the resulting orange suspension was left to stir at ambient temperature. Within several minutes the suspension darkened to brown/green in colour. After 2 hours, the suspension was filtered through Celite and the orange filtrate was reduced to approximately 1 mL in volume. Addition of hexane afforded an oily orange solid which was washed repeatedly with hexane and dried in vacuo. Yield: 0.215 g (74%).
In an Ar filled flask, 0.070 g (0.11 mmol) [RuCl2(p-cymene)]2 and 0.045 g (0.11 mmol) of AgBF4 were combined. CH2Cl2 (10 mL) was added and the resulting orange suspension was left to stir at ambient temperature. Within several minutes the suspension darkened to brown/green in colour. After 2 hours, the suspension was filtered through Celite and the orange filtrate was collected and set to stir. A solution of R-BINAP (0.142 g, 0.11 mmol) in toluene (5 mL) was added. The resulting solution was stirred for several minutes. Solid R,R-cydn (0.026 g, 0.11 mmol) was added. The resulting solution was heated to 60° C. for approximately 3 hours. The resulting solution was concentrated to dryness leaving an orange residue. A sample of the residue was employed in the catalytic hydrogenation of acetophenone according to the conditions described below. Result: time=2 h; conv.=>99%; ee=84%.
Yet another route exists via an ill-defined mixture of ruthenium-diphosphine-DMF complexes (DMF=dimethylformamide) reported in the literature (Noyori et al., Tetrahedron Letters, 1991, 32, 4163). The mixture is believed to consist of the following components: RuCl2(diphosphine)(DMF)2 and [RuCl2(diphosphine)(DMF)]n). Thus, treatment of the RuCl2(BINAP)(DMF)2 and [RuCl2(BINAP)(DMF)]n) mixture with an equivalent of an anion abstracting agent (e.g. AgBF4) to generate a cationic precursor which then react with a diamine (e.g. R,R-cydn) to yield the cationic ruthenium-diphosphine-diamine complex, [RuCl(R-BINAP)(R,R-cydn)]BF4. This synthetic route is presented in Scheme 3 below. It should be noted that the product of this reaction also appears to be a mixture of the DMF-coordinated cation and the DMF-free cation.
This procedure can also be applied to the synthesis of compounds (I), (III) and (V) of this disclosure.
In an Ar filled flask, 0.250 g (0.50 mmol) of [RuCl2(C6H6)]2 and 0.622 g (1.00 mmol) of R-BINAP were combined. DMF (5 mL) was added and the resulting brown suspension was set to stir in a 100° C. oil bath. After 15 minutes, the suspension had cleared to a red/brown solution. The flask was removed from the oil bath and allowed to cool to RT. The solution was then concentrated to an oily residue and Et2O (20 mL) was added affording brick red solids. The solids were filtered off in air, washed with Et2O (5×5 mL) and dried in vacuo. Yield: 0.820 g (87%). 31P NMR (ppm, CD2Cl2): several broad doublets between 50-62 ppm.
In an Ar filled flask, 0.200 g (0.21 mmol) of RuCl2(R-BINAP)(DMF)2 and 0.041 g (0.21 mmol) of AgBF4 were combined. CH2Cl2 (10 mL) was added and the resulting brown suspension was set to stir at ambient temperature. After 2 hours, 0.024 g (0.21 mmol) of R,R-cydn in CH2Cl2 (1 mL) was added and the suspension quickly changed to green in colour. The suspension was stirred for a further 2 hours and then filtered through a 0.45 mm PTFE syringe filter. The green filtrate was concentrated to approximately 1 mL and Et2O (20 mL) was added affording green solids. The solids were filtered off in air, washed with Et2O (4×5 mL) and dried in vacuo. Yield: 0.186 g (85%). 31P NMR (ppm, CD2Cl2): 7.38 (d, JPP=45 Hz), 67.4 (d, JPP=45 Hz). These chemical shift values match those for the same compound prepared via treatment of RuCl2(R-BINAP)(R,R-cydn) with one equivalent of AgBF4. Minor peaks are also present between 48-54 ppm which are consistent with the presence of a small amount of a DMF adduct of the form “[RuCl(R-BINAP)(R,R-cydn)(DMF)]BF4” which would account for the green colour (vs. orange for the same material prepared via treatment of RuCl2(R-BINAP)(R,R-cydn) with AgBF4).
In an Ar filled flask, 0.200 g (0.21 mmol) of RuCl2(R-BINAP)(DMF)2 and 0.185 g (0.21 mmol) of Li(OEt2)2.5[B(C6F5)4] were combined. CH2Cl2 (10 mL) was added and the resulting brown suspension was set to stir at ambient temperature. After 2 hours, 0.024 g (0.21 mmol) of R,R-cydn in CH2Cl2 (1 mL) was added and the suspension gradually changed to green in colour. The suspension was stirred for a further 2 hours and then filtered through a 0.45 mm PTFE syringe filter. The green filtrate was concentrated to approximately 1 mL and hexane (20 mL) was added affording green solids. The solids were filtered off in air, washed with hexane (4×5 mL) and dried in vacuo. Yield: 0.333 g (96%). 31P NMR (ppm, CD2Cl2): 7.31 (d, JPP=45 Hz), 67.4 (d, JPP=45 Hz). These chemical shift values match those for the same compound prepared via treatment of RuCl2(R-binap)(R,R-cydn) with one equivalent of Li(OEt2)2.5[B(C6F5)4]. Minor peaks are also present between 52-54 ppm which are consistent with a dmf adduct of the form “[RuCl(R-BINAP)(R,R-cydn)(DMF)]B(C6F5)4” which would account for the green colour (vs. orange for the same material prepared via treatment of RuCl2(R-BINAP)(R,R-cydn) with Li(OEt2)2.5[B(C6F5)4]).
Another route to a cationic ruthenium catalyst exists through the stable precursor RuCl2(diphosphine)(pyridine)2. It has been determined that RuCl2(diphosphine)(pyridine)2 is a highly useful and convenient precursor to complexes of the type [RuCl(diphosphine)(diamine)LB]X and [RuCl(diphosphine)-(aminophosphine)LB]X. The precursor, RuCl2(diphosphine)(pyridine)2 is a well defined, single component (in contrast to the DMF analogue of Example 4). RuCl2(diphosphine)(pyridine)2 can be prepared from the corresponding DMF complex or in an analogous method to the preparation for the DMF complex wherein pyridine is used instead of DMF, as shown in Scheme 4.
The precursor compound RuCl2(diphosphine)(pyridine)2 is readily derivatized into its cationic counterpart, [RuCl(diphopshine)(pyridine)2]BF4, by treatment with an anion abstracting agent (e.g. AgBF4 as set out in Scheme 5).
The cation, an air stable solid which can be isolated in high yields and stored under ambient conditions, is a convenient precursor to other cationic hydrogenation catalysts. The cationic pyridine compound can be derivatized by treatment with a diamine into compounds of the type [RuCl(diphosphine)(diamine)]BF4 (Examples 5(a) and (b)).
An alternate route to complexes of the type [RuCl(diphosphine)(pyridine)2]+ via a ruthenium-norbornadiene (NBD) complex which is equally valuable is outlined below in Scheme 6. It should be noted that pyridine can be replaced by any Lewis base and the product can be further derivatized to complexes of the type [RuCl(diphosphine)(diamine)LB]X and [RuCl(diphosphine)(aminophosphine)LB]X (where LB is Lewis base).
The procedures described in this Example can be generalized into the following method for the preparation of cationic or dicationic catalysts:
wherein M, X and LB are as defined for the compounds of the disclosure and diphosphine is a P2 ligand as defined for the compounds of the disclosure and ligand is a neutral displaceable ligand such as p-cymene, benzene, COD and NBD and x is an integer that depends on the structure of the complex (typically x is 2).
The cationic catalysts derived from the precursors described in this Example have been tested in hydrogenation using identical procedures as for the cations derived from treatment of the RuCl2(diphosphine)(diamine) or RuCl2(diphosphine)(PN) complexes with anion abstracting agents in the presence of Lewis bases. The complexes prepared via the [RuCl(PP)(py)2]BF4 precursor display essentially identical behavior in hydrogenation of acetophenone.
To a CH2Cl2 solution of [RuCl(R-binap)(py)2]BF4 (0.08 g, 0.0796 mmol) was added a CH2Cl2 solution of the R-R-cydn (9.1 mg, 0.0796 mmol) under inert (Ar) atmosphere. The reaction mixture was allowed to stir overnight at ambient temperature. The solution was then concentrated, and the residue was recrystallized from CH2Cl2/Et2O. The solid that precipitated was then filtered in air to obtain an amber-yellow color solid. Yield: 0.06 g, 70%. This catalyst was examined for its catalytic ability to convert acetophenone to its corresponding alcohol, and showed a 98% conversion with an enantiomeric excess of 80%.
To a CH2Cl2 solution of the [RuCl(R-binap)(py)2]BF4 (0.077 g, 0.0770 mmol) was added a CH2Cl2 solution of 2-(diphenylphosphino)ethylamine (17.6 mg, 0.0770 mmol) under inert atmosphere. The reaction mixture was allowed to stir overnight at ambient temperature. During this time some precipitate formed. The solution was then filtered, the filtrate was concentrated, and the residue was recrystallized from CH2Cl2/Et2O. The solid that precipitated was then filtered in air to obtain an amber-yellow color solid. Yield: 0.05 g, 54%. This catalyst was examined for its catalytic ability to convert acetophenone to its corresponding alcohol, and showed a 72% conversion and an enantiomeric excess of 22%.
The first step of the reaction is carried out in air. To a 500 mL schlenk flask containing a pear-shaped stirring bar is charged with a ethanol solution (200 mL) of RuCl3.3H2O, and bicycle[2.2.1]hepta-2,5-diene(norbornadiene) (10 mL, 0.12 mol). The mixture is vigorously stirred at room temperature for 24 hour. During this time the brick red to brown solid precipitated from the solution. On completion of the reaction the suspension is filtered using a medium porosity glass filter frit and washed thoroughly with acetone (50 mL). Drying of the solid gives 3.8 g of insoluble brick red solid. (ref Inorganic Syntheses. New York: John Wiley and Sons, 1989: 250-251)
The second step of the reaction is carried out under Argon and the work-up procedure was slightly modified from the original literature. [(NBD)RuCl2]x (2.0 g, 7.57 mmol) was rapidly stirred in pyridine (50 mL) for 1 week at room temperature under argon. The mixture changed from brown to greenish-yellow over this period. The pyridine was then removed under vacuum to give a greenish yellow solid. The solid was then dissolved in CH2Cl2 and the insoluble black material was filtered off. The CH2Cl2 solution was then concentrated, and recrystallized from hexanes 2 times, yielding a dark-orange crystalline materials. Yield: 3.0 (93%). 1H NMR (400 MHz, CD2Cl2): d 1.55 (br s, 2H, CH2), 4.05 (br s, 2H, bridgehead CH), 4.85 (m, 4H, olefin), 7.25 (br t, J=11.9 Hz, 4H), 7.7 (br t, J=11.9 Hz, 2H), 8.54 (br d, J=12.0 Hz, 4H).(ref Chirality 2000, 12: 514-522)
The third step of the reaction is carried out in the dry box. To a small vial is charged (NBD)RuCl2(Pyridine)2 (0.1 g, 0.23 mmol) and 1 equiv. of AgBF4 (46 mg, 0.23 mmol) and CH2Cl2 (5 mL). The solution was allowed to stir for 1 hour. Precipitate was observed during this period. The precipitate was then filtered off, and the filtrate was concentrated and recrystallized from Et2O to obtain a pale greenish-yellow solid. Yield: 80 mg, 72%.
In an Ar filled flask, 0.100 g (0.11 mmol) of RuCl2(R-binap)(R,R-cydn) and 0.045 g (0.24 mmol) of AgBF4 were combined. CH2Cl2 (7 mL) was added and the resulting rust coloured suspension was left to stir at ambient temperature for two hours after which time it was filtered through Celite. The orange filtrate was reduced to dryness leaving a yellow/orange residue. Yield: 0.085 g (77%). 31P NMR (ppm, CD2Cl2): 0.48 (d, JPP=39 Hz), 64.89 (d, JPP=39 Hz).
In an Ar filled flask, 0.115 g (0.11 mmol) of RuCl2(R-binap)(Ph2PCH2CH2NH2) and 0.044 g (0.24 mmol) of AgBF4 were combined. CH2Cl2 (7 mL) was added and the resulting dark orange suspension was left to stir at ambient temperature for two hours after which time it was filtered through Celite. The yellow filtrate was concentrated to approximately 1 mL in volume and Et2O was added (10 mL) affording pale yellow solids. The solids were filtered off, washed with Et2O (3×5 mL) and dried in vacuo. Yield: 0.119 g (94%). 31P NMR (ppm, CD2Cl2): 15.3 (d, JPP=18 Hz), 17.2 (d, JPP=18 Hz), 62.2 (br m).
In an Ar filled flask, 0.200 g (0.20 mmol) of RuCl2(R,R-DPPcydn) and 0.093 g (0.48 mmol) of AgBF4 were combined. CH2Cl2 (7 mL) was added and the resulting dark yellow/green suspension was left to stir at ambient temperature for two hours after which time it was filtered through Celite. The yellow filtrate was concentrated to approximately 1 mL in volume and Et2O was added (10 mL) affording pale yellow solids. The solids were filtered off, washed with Et2O (3×5 mL) and dried in vacuo. Yield: 0.169 g (92%). 31P NMR (ppm, CD2Cl2): broad signals at 42.2 and 63.3 ppm barely discernable above baseline.
Acetonitrile (5 mL) was added to 210 mg (0.319 mmol) of N1,N2-bis(2-(diphenylphosphino)benzylidene)cyclohexane-1,2-diamine, (R,R)-cyP2N2 and 102 mg (0.302 mmol) of iron(II)tetrafluoroborate hexahydrate[Fe(OH2)6][BF4]2 and the mixture was stirred for one hour. The solution was concentrated to ca. 1 mL and then 20 mL of diethyl ether was added dropwise. The mixture was stirred for 30 minutes and then the solid was collected on a glass frit and dried in vacuo. Yield: 240 mg, 82%. 31P{1H} NMR (121 MHz, CD3CN): 52.7 ppm.
A solution of N1,N2-bis(2-(ditolylphosphino)benzyl)(R,R)-cyclohexane-1,2-diamine(R,R)-cyPAr2(NH)2 (149 mg, 0.207 mmol) and iron(II)tetrafluoroborate hexahydrate[Fe(OH2)6][BF4]2 (70 mg, 0.207 mmol) was stirred at r.t. in MeCN (5 mL) for 20 min. The resulting purple solution was concentrated to 1 mL and 10 mL of Et2O were added. A purple powder precipitated and was isolated by filtration. Yield: 170 mg, 87%. 31P{1H} NMR (121 MHz, CD3CN): 35.3 ppm.
A solution of N1,N2-bis(2-(dixylylphosphino)benzyl)(R,R)-cyclohexane-1,2-diamine (R,R)-cyPAr2(NH)2 (161 mg, 0.207 mmol) and iron(II)tetrafluoroborate hexahydrate [Fe(OH2)6][BF4]2 (70 mg, 0.207 mmol) was stirred at r.t. in MeCN (5 mL) for 20 min. The resulting purple solution was concentrated to 1 mL and 10 mL of Et2O were added. A purple powder precipitated and was isolated by filtration. 3: Yield: 190 mg, 91%. 31P{1H} NMR (121 MHz, CD3CN): 39.2 ppm.
A solution of N1,N2-bis(2-(3,5-di-tert-butyl-4-methoxy-phenylphosphino)benzyl)(R,R)-cyclohexane-1,2-diamine (R,R)-cyPAr2(NH)2 (255 mg, 0.207 mmol) and iron(II)tetrafluoroborate hexahydrate [Fe(OH2)6][BF4]2 (70 mg, 0.207 mmol) was stirred at r.t. in MeCN (5 mL) for 20 min. The resulting brown solution was concentrated to 1 mL and 10 mL of Et2O were added. A beige-brown powder precipitated and was isolated by filtration. Yield: 190 mg, 91%. 31P{1H} NMR (121 MHz, CD3CN): 47.5 ppm.
Synthesis of [Fe(NCMe)2((R,R)-dpenPPh2N2)][BF4]2, (5). A solution of (1R,2R)-(+)-1,2-diphenylethylenediamine (63 mg, 0.297 mmol), 2-(diphenylphosphino)benzaldehyde (172 mg, 0.593 mmol), and iron(II)tetrafluoroborate hexahydrate [Fe(OH2)6][BF4]2 (100 mg, 0.296 mmol) was stirred overnight under reflux in MeCN (5 mL). The red orange solution was concentrated to 1 mL and 10 mL of Et2O were added. A red-orange powder precipitated and was isolated by filtration. Yield: 290 mg, 92%. 31P{1H} NMR (121 MHz, CD3CN): 52.3 ppm.
A solution of [Fe(NCMe)2((R,R)-dpen-PPh2N2)][BF4]2 (130 mg, 0.122 mmol) and tBuNC (14 μL, 0.122 mmol) in acetone (3 mL) was stirred for 15 min. The resulting orange-yellow solution was evaporated to dryness to give an orange powder). 6: Yield: 55 mg, 41%. 31P{1H} NMR (121 MHz, CD3CN): 56.1 (2JP-P=48 Hz), 44.8 (2JP-P=48 Hz) ppm.
A solution of [Fe(NCMe)2((R,R)-cy-PPh2N2)][BF4]2 (40 mg, 0.039 mmol) and NaBArF (71 mg, 0.079 mmol) in dichloromethane (5 mL) was stirred for 1 hour. The resulting orange-yellow solution was filtered on celite and evaporated to dryness to give an orange powder. 7: Yield: 90 mg, 89%. 31P{1H} NMR (121 MHz, CD3CN): 55.2 (2JP-P=54 Hz), 48.1 (2JP-P=54 Hz) ppm.
A solution of Fe(NCMe)2((R,R)-dpenPPPh2N2)][BF4]2 (185 mg, 0.173 mmol) in acetone (10 mL) was stirred under CO overnight. The resulting orange solution was evaporated to dryness to give an orange powder. The NMR of the crude product shows an AB pattern characteristic of the formation of [Fe(CO)(NCMe)((R,R)-dpenPh2N2)][BF4]2, (7) (purity<50%) with other unidentified impurities. 31P{1H} NMR (121 MHz, CD3CN): 52.9 (2JP-P=40 Hz), 49.7 (2JP-P=40 Hz), 9.1, −2.4, −19.6, −22.1 ppm.
A solution of acetophenone (1.0 g, 8.3 mmol) in 2-propanol (10 ml) was added to a 50 mL Schlenk flask. After evacuating and refilling with argon, a mixture of catalyst (e.g. [RuCl(R-binap)(R,R-cydn)]BF4; 0.01 mmol) and KtOBu (20 mg, 0.18 mmol) was added. The resulting mixture was then injected into a 100 mL autoclave which had been previously placed under an atmosphere of H2. The autoclave was pressurized to 200 psig and the reaction mixture was stirred at ambient temperature. The reaction progress was monitored by TLC. Upon completion of the reaction, the solvent was removed under vacuum and the mixture was filtered through silica gel (ca. 6 cm) using 3:1 hexane:ethyl acetate. The solvent was removed from the filtrate affording the product as a colorless liquid. Results are shown in Tables 1-9.
A solution of 2,3,3-trimethylindolenine (0.286 g, 1.8 mmol) in 2-propanol (10 mL) was added to a 50 mL Schlenk flask. After evacuating and refilling with argon, a mixture of catalyst (0.01 mmol) and KOtBu (29 mg, 0.26 mmol) was added. The resulting mixture was then injected into a 100 mL autoclave which had been previously placed under an atmosphere of H2. The autoclave was pressurized to 150 psi and the reaction mixture was stirred at ambient temperature. A solution of Na2CO3 was added to render the mixture basic. The product was extracted with CH2Cl2. The resulting organic phases were dried on MgSO4, filtered and evaporated to dryness. The 1H NMR analysis was used to calculate the conversion. The sample was purified by chromatography on silica gel using hexane and ethyl acetate and submitted for HPLC analysis to determine the e.e. The results are presented in Table 10.
A solution of norcamphor (0.64 g, 5.82 mmol) in 2-propanol (5 mL) was added to a 50 mL Schlenk flask. After evacuating and refilling with argon, a mixture of catalyst (i.e. [RuCl(Ph2PCH2CH2NH2)2]BF4; 0.010 g, 0.015 mmol) and KtOBu (0.02 g, 0.18 mmol) in 2-propanol (5 mL) was added. The resulting mixture was then injected into a 100 mL autoclave which had been previously placed under an atmosphere of H2. The autoclave was pressurized to 200 psig and the reaction mixture was stirred at ambient temperature. The reaction progress was monitored 1H NMR. Results for [RuCl(Ph2PCH2CH2NH2)2]BF4:99:1 endo:exo.
Under argon, a solution of degassed acetophenone (120 mg, 1 mmol) and KOtBu (4.5 mg, 0.04 mmol) was added to a Schlenk flask. The resulting mixture was then injected into a 100 mL autoclave which already contains the iron catalyst (5 mg, 0.005 mmol) and 6 mL of degassed 2-propanol. under an atmosphere of H2. The autoclave was pressurized to 25 atm and the reaction mixture was stirred at 50° C. After 17 hours, the sample was then filtered through silica gel (ca. 2 cm) using CH2Cl2 and submitted for GC analysis. The results are shown in Table 11.
Under argon, the iron complex (5 mg, 0.005 mmol), KOtBu (5 mg, 0.045 mmol) and acetophenone (120 mg, 200 equiv) were stirred in 5 mL of 2-propanol at r.t. The sample was then filtered through silica gel (ca. 2 cm) using CH2Cl2 and submitted for GC analysis. The results are shown in Table 12.
While the present disclosure has been described with reference to what are presently considered to be the preferred examples, it is to be understood that the disclosure is not limited to the disclosed examples. To the contrary, the disclosure is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
All publications, patents and patent applications are herein incorporated by reference in their entirety to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated by reference in its entirety. Where a term in the present application is found to be defined differently in a document incorporated herein by reference, the definition provided herein is to serve as the definition for the term.
a S:C:B = 830:1:18, iPrOH, r.t., PH2 = 150 psi
a S:C:B = 180:1:26, iPrOH, r.t., 150 psi
AS:C:B = 200:1:8, S = PhCOMe, C = catalyst, B = KOtBu;
AS = PhCOMe, C = catalyst, B = KOtBu;
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/CA2008/001905 | 10/30/2008 | WO | 00 | 4/22/2010 |
| Number | Date | Country | |
|---|---|---|---|
| 60983722 | Oct 2007 | US | |
| 61015434 | Dec 2007 | US | |
| 61049869 | May 2008 | US |
