Chiral monophosphorus compounds

Description

This application is a Divisional of Ser. No.10/256,700 filed on Sep. 27, 2002.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to catalysts comprising chiral monophosphorus compounds and their use, the chiral monophosphorus compounds themselves and also their precursors. For the purposes of the invention, chiral monophosphorus compounds are, in particular, chiral monophosphites, monophosphoramidites and monophosphonites.

2. Brief Description of the Prior Art

It is already known that chiral monophosphites or their transition metal complexes can be used for asymmetric syntheses (cf. A. Alexakis, Tetrahedron Asymmetry, 1997, 8, 3193-3196; C. Claver et al., Chem. Commun., 2000, 2383-2384; W. Chen, J. Xiao, Tetrahedron Letters, 42, 2001, 2897-2899; M. Reetz, G. Mehler, Angew. Chem., 2000, 112, 4047-4049). The use of chiral monophos-phoramidites or their transition metal complexes in asymmetric syntheses is known, for example from van den Berg et al., J. Am. Chem. Soc., 2000, 122, 11539-11540, and H. Waldmann, Chem. Eur. J. 2000, 6, 671-675, and the use of chiral monophosphonites is known from C. Claver et al., Chem. Commun., 2000, 961-962.

However, all chiral ligands known hitherto are derived from the basic framework of 2,2′-dihydroxy-1,1′-binaphthyl or other polycyclic dihydroxybisaryls. The dis-advantage of such ligands is that only limited substitution opportunities are available for varying the electronic and steric properties. Use in various asymmetric reaction types and applicability to many substrates does, however, make a broad range of possible substitutions desirable.

Furthermore, there is a need to develop catalysts which, particularly when used in asymmetric hydrogenations, give not only a high enantioselectivity but also high conversions and mild to moderate reaction conditions.

SUMMARY OF THE INVENTION

It has now surprisingly been found that chiral monophosphorus compounds of the general formula (I) or catalysts based on these are particularly suitable for asymmetric syntheses,
where

• • R¹ is an unsubstituted or substituted 1,1′-biphenyl-2,2′-diyl radical and R² is a radical selected from the group consisting of substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted alkoxy, substituted or unsubstituted aryloxy and tertiary amino.
  • R² is preferably substituted or unsubstituted alkoxy or substituted or unsubstituted aryloxy or tertiary amino, particularly preferably substituted or unsubstituted alkoxy or substituted or unsubstituted aryloxy.

DETAILED DESCRIPTION OF THE INVENTION

The following is a detailed description of the invention with particular reference to its preferred elements. Unsubstituted or substituted alkyl is, by way of example and preferably, an unbranched, branched, cyclic or acyclic C₁-C₁₈-alkyl radical which is either unsubstituted or at least partially substituted by fluorine, chlorine, bromine, oxo, hydroxy, unsubstituted or substituted aryl, C₁-C₆-alkoxy such as methoxy, ethoxy, isopropoxy or n-propoxy, n-butoxy, or tert-butoxy, primary, secondary or tertiary amino, cyano or carboxyl groups or derivatives thereof. Examples of derivatives of carboxyl groups are esters, amides and salts.

Unsubstituted or substituted alkyl is particularly preferably a branched, cyclic or acyclic C₃-C₁₂-alkyl radical which is either unsubstituted or at least partially substituted by fluorine, oxo, hydroxy, methoxy, ethoxy, phenyl, 2-methoxyphenyl, 2-pyridyl, 3-pyridyl, 4-pyridyl, amino, dimethylamino, diethylamino, diisopropylamino, cyano or carboxyl groups, their salts such as sodium or potassium salts or their esters such as methyl or ethyl esters or their amides such as dimethylamides or diethylamides.

Unsubstituted or substituted alkyl is very particularly preferably isopropyl, tert-butyl, cyclohexyl, 1-butyl, 2-butyl, 2-ethylhex-1-yl, benzyl, 2-methoxybenzyl, 2-pyridylmethyl, 1-phenylethyl.

Unsubstituted or substituted alkoxy is, by way of example and preferably, an unbranched, branched, cyclic or acyclic C₁-C₁₈-alkoxy radical which is either unsubstituted or at least partially substituted by fluorine, chlorine, bromine, oxo, free or protected hydroxy, C₁-C₆-alkoxy such as methoxy, ethoxy, isopropoxy or n-propoxy, n-butoxy or tert-butoxy, substituted or unsubstituted C₆-C₁₀-aryl such as phenyl or 2-pyridyl, primary, secondary or tertiary amino, cyano or carboxyl groups or derivatives thereof.

Unsubstituted or substituted alkoxy is particularly preferably an unbranched, branched, cyclic or acyclic C₂-C₁₂-alkoxy radical which is either unsubstituted or at least partially substituted by fluorine, chlorine, free or protected hydroxy, substituted or unsubstituted phenyl, 2-pyridyl, C₁-C₆-alkoxy such as methoxy, ethoxy, isopropoxy or n-propoxy, n-butoxy or tert-butoxy, C₁-C₆-dialkylamino, C₁-C₆-alkylcarbonylamino, benzoylamino, 4-methylphenylsulphonylamino, imidazolyl, phthalimidyl, C₁-C₆-alkyloxycarbonyl, C₁-C₄-dialkylaminocarbonyl.

Unsubstituted or substituted alkoxy is very particularly preferably an unbranched, branched, cyclic or acyclic C₂-C₆-alkoxy radical which is either unsubstituted or at least partially substituted by fluorine, chlorine, free or protected hydroxy, mono-substituted or disubstituted or unsubstituted phenyl, 2-pyridinyl, C₁-C₄-dialkylamino, C₁-C₄-alkylcarbonylamino, benzoylamino, 4-methylphenyl-sulphonylamino, imidazolyl, phthalimidyl, C₁-C₄-alkyloxycarbonyl, C₁-C₄-dialkyl-aminocarbonyl, C₁-C₄-alkoxy such as methoxy, ethoxy, isopropoxy or n-propoxy, n-butoxy or tert-butoxy.

Unsubstituted or substituted alkoxy is even more preferably methoxy, ethoxy, isopropoxy, cyclohexyloxy, phenoxy, (R)-1-phenylethoxy or (S)-1-phenylethoxy.

Substituted or unsubstituted aryl is, by way of example and preferably, a carbocyclic aromatic radical having from 6 to 18 framework carbon atoms or a heteroaromatic radical having from 5 to 18 framework carbon atoms in which no, one, two or three framework carbon atoms per ring, but at least one framework carbon atom in the total molecule, can be replaced by heteroatoms selected from the group consisting of nitrogen, sulphur and oxygen. Furthermore, the carbocyclic aromatic radicals or heteroaromatic radicals can be substituted by up to five identical or different substituents per ring selected from the group consisting of free or protected hydroxy, iodine, bromine, chlorine, fluorine, cyano, free or protected formyl, C₁-C₁₂-alkyl such as methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, cyclohexyl, n-hexyl, n-octyl or isooctyl, C₆-C₁₂-aryl such as phenyl, tri(C₁-C₆-alkyl)siloxyl such as trimethylsiloxyl, triethylsiloxyl or tri-n-butylsiloxyl and radicals of the general formula (II),
A-B-D-E   (II),
where, independently of one another,

• • A is absent or is a C₁-C₈-alkylene radical such as methylene, 1,2-ethylene, 1,1-ethylene, 1,3-propylene, 1,2-propylene, 1,4-butylene or 2,3-butylene and
  • B is absent or is oxygen, sulphur or NR³,
    • where
    • R³ is hydrogen, C₁-C₁₆-alkyl such as methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, cyclohexyl, n-hexyl, n-octyl or isooctyl or C₆-C₁₀-aryl such as phenyl or 2-, 3- or 4-tolyl and
    • D is a carbonyl group and
    • E is R⁴, OR⁴, NHR⁵ or N(R⁵R⁶)₂,
      • where
      • R⁴ is C₁-C₁₂-alkyl, C₆-C₁₀-aryl and
      • R⁵ and R⁶ are each, independently of one another, C₁-C₈-alkyl or C₆-C₁₀-aryl or the N(R⁵R⁶)₂ moiety is a cyclic amino radical,
        and radicals of the general formulae (IIIa) and (IIIb)
        A-E   (IIIa)
        A-COX   (IIIb)
        where A and E are as defined above and X is OH, NH₂ or OM, where M can be an alkali metal ion, half an equivalent of an alkaline earth metal ion, an ammonium ion or an organic ammonium ion.

Examples of carbocyclic aromatic radicals having from 6 to 18 framework carbon atoms are phenyl, naphthyl, phenanthrenyl, anthracenyl or fluorenyl, heteroaromatic radicals having from 5 to 18 framework carbon atoms in which no, one, two or three framework carbon atoms per ring, but at least one framework carbon atom in the total molecule, can be replaced by heteroatoms selected from the group consisting of nitrogen, sulphur and oxygen are, for example, pyridinyl, oxazolyl, thienyl, benzofuranyl, benzothienyl, dibenzofuranyl, dibenzothienyl, furanyl, indolyl, pyridazinyl, pyrazinyl, pyrimidinyl, triazolyl or quinolinyl.

For the purposes of the invention, protected formyl is a formyl radical which has been protected by conversion into an aminal, acetal or a mixed aminal-acetal, with the aminals, acetals and mixed aminal-acetals being able to be acyclic or cyclic.

For the purposes of the invention, protected hydroxy is a hydroxy radical which has been protected by conversion into an acetal, carbonate, carbamate or carboxylate. Examples are conversion into a tetrahydropyranyl adduct, into a benzyloxycarbonyl, allyloxycarbonyl or tert-butyloxycarbonyl derivative.

Substituted or unsubstituted aryloxy is, by way of example and preferably, a radical of the formula (IV)
—O—Ar   (IV)
where Ar has the same widest meaning as indicated above for substituted or unsubstituted aryl.

Unsubstituted or substituted aryloxy is particularly preferably a radical of the general formula (IV), in which Ar is phenyl, naphthyl, anthracenyl, phenanthrenyl, pyridinyl, pyrazinyl, pyridazinyl or pyrimidinyl which can be substituted by no, one, two or three further substituents per ring selected from the group consisting of free or protected hydroxy, bromine, chlorine, fluorine, cyano, methyl, ethyl, n-propyl, isopropyl, n-butyl, n-pentyl, n-hexyl, phenyl, benzyl, C₁-C₁₂-perfluoroalkyl such as trifluoromethyl, pentafluoroethyl, and substituents of the general formulae (II) and (IIIa) and (IIIb) in which, in each case independently of one another,

• • A is absent or is methylene,
  • B is absent or is oxygen or NR³,
    • where
    • R³ is hydrogen, methyl or ethyl and
    • D is a carbonyl group and
    • E is R⁴, OR⁴, NHR⁵ or NR⁵R⁶,
      • where
      • R⁴ is methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, benzyl, 2-hydroxyethyl, trifluoromethyl or phenyl and
      • R⁵ and R⁶ are each, independently of one another, methyl, ethyl, n-propyl, isopropyl, n-butyl, benzyl, 2-hydroxyethyl or phenyl or
      • the NR⁵R⁶ moiety is morpholinyl, piperidinyl or pyrolidinyl and
      • X is OH, NH₂, or OM, where M is a sodium, potassium or ammonium ion.

Unsubstituted or substituted aryloxy is very particularly preferably a radical of the general formula (IV), in which Ar is phenyl which is substituted by no, one or two further substituents selected from the group consisting of fluorine, chlorine, cyano, methoxy, methyl, ethyl, phenyl, trifluoromethyl, and radicals of the general formulae (II) and (IIIa) and (IIIb) in which

• • A and B are absent and
  • D is a carbonyl group and
  • E is R⁴ or OR⁴,
    • where
    • R⁴ is methyl, ethyl or phenyl.

Unsubstituted or substituted aryloxy is even more preferably phenoxy, 2,4-di-methylphenoxy, 3,5-dimethylphenoxy, 3,5-bis(trifluoromethyl)-phenoxy, 4-methylphenoxy, 3-methylphenoxy, 3-methoxyphenoxy, 4-methoxyphenoxy, 2-methoxyphenoxy, 2-methylphenoxy, 2,4-dichlorophenoxy, 2-ethoxycarbonyl-phenyl, 2-methoxycarbonyl, 2-acetylphenyl, 4-acetylphenyl or 2,6-dimethylphenoxy.

Tertiary amino is, for example, alkylarylamino, dialkylamino or diarylamino, preferably dialkylamino or diarylamino. Cyclic amino radicals are also encompassed by the invention.

Preferred examples of tertiary amino are di(substituted or unsubstituted (C₁-C₁₂-alkyl)amino such as dimethylamino, diethylamino, diisopropylamino, di-n-butylamino, di-(R)-phenylethylamino, di-(S)-phenylethylamino, dibenzylamino and di(substituted or unsubstituted C₆-C₁₀-aryl)amino, such as diphenylamino, di-(p-tolyl)amino or cyclic amino radicals such as R,R-dimethylpyrrolidino, S,S-dimethylpyrrolidino, morpholino, piperidino, tetramethylpiperidino.

• • R¹ is, by way of example and preferably, an unsubstituted or substituted 1,1′-biphenyl-2,2′-diyl radical of the general formula (VI),
    where the radicals R⁷, R⁸, R⁹and R¹⁰ are each selected independently from the group consisting of fluorine, chlorine, bromine, unsubstituted or substituted protected hydroxy, unsubstituted or substituted C₁-C₆-alkyl, unsubstituted or substituted C₁-C₆-alkoxy, unsubstituted or substituted C₁-C₆-alkylthio, cyano, free or protected formyl, unsubstituted or substituted C₆-C₁₂-aryl, tri(C₁-C₆-alkyl)siloxyl and radicals of the general formula (II),
    A-B-D-E   (II),
    where, independently of one another,
  • A is absent or is a C₁-C₈-alkylene radical and
  • B is absent or is oxygen, sulphur or NR³,
    • where
    • R³ is hydrogen, C₁-C₁₆-alkyl or C₆-C₁₀-aryl and
    • D is a carbonyl group and
    • E is R⁴, OR⁴, NHR⁵ or NR⁵R⁶,
      • where
      • R⁴ is C₁-C₁₂-alkyl or C₆-C₁₀-aryl and
      • R⁵ and R⁶ are each, independently of one another, C₁-C₈alkyl or C₆-C₁₀-aryl or the NR⁵R⁶ moiety is a cyclic amino radical,
        and radicals of the general formulae (IIIa) and (IIIb) with the widest meaning indicated above.

The two radicals R¹⁰ together can also be bridging. The invention also encompasses cases in which the two radicals R¹⁰ are each chiral or are together chiral and bridging.

Furthermore, the two radicals can also form a nonaromatic ring.

R¹ is particularly preferably an unsubstituted or substituted 1,1′-biphenyl-2,2′-diyl radical of the general formula (VI) in which the radicals R⁷, R⁸, R⁹ and R¹⁰ are each selected independently from the group consisting of fluorine, chlorine, bromine, free or protected hydroxy, unsubstituted or substituted C₁-C₄-alkyl, unsubstituted or substituted C₁-C₄-alkoxy, unsubstituted or substituted C₁-C₄-alkylthio, cyano, C₆-aryl, tri(C₁-C₄-alkyl)siloxyl and radicals of the general formula (II),
A-B-D-E   (II)
where, independently of one another,

• • A is absent or is a C₁-C₄-alkylene radical and
  • B is absent or is oxygen or NR³,
  • where R³ is hydrogen, C₁-C₆-alkyl or C₆-C₁₀aryl and
  • D is a carbonyl group and
  • E is R⁴, OR⁴, NHR⁵ or NR⁵R⁶,
  • where R⁴ is C₁-C₆-alkyl or C₆-C₁₀aryl and
  • R⁵ and R⁶ are each, independently of one another, C₁-C₄-alkyl or C₆-aryl or the NR⁵R⁶ moiety is a cyclic amino radical,
  • and radicals of the general formulae (IIIa) and (IIIb) with the widest meaning indicated above.

The two radicals R¹⁰ can together also be bridging. Bridges formed in this way are, preferably and by way of example, bridges of the formula (VII)
—O-G¹-K-G²-O—  (VII)
where G¹ and G² can each, independently of one another, either be absent or be a carbonyl group or a carbonylamino group,

• • K can be an unsubstituted or substituted C₂-C₆-alkylene chain.
  • R¹ is very particularly preferably an unsubstituted or substituted 1,1′-biphenyl-2,2′-diyl radical of the general formula (VI) in which the radicals R⁷, R⁸, R⁹ and R¹⁰ are each selected independently from the group consisting of fluorine, chlorine, bromine, free or protected hydroxy, unsubstituted or substituted C₁-C₄-alkyl, unsubstituted or substituted C₁-C₄-alkoxy and radicals of the general formula (II),
    A-B-D-E   (II)
    in which, independently of one another,
  • A is absent and
  • B is absent or is oxygen,
    and
  • D is a carbonyl group and
  • E is R⁴, OR⁴, NHR⁵ or NR⁵R⁶,
  • where R⁴ is C₁-C₄-alkyl or C₆-C₁₀-aryl and
  • R⁵ and R⁶ are each, independently of one another, C₁-C₄-alkyl or the NR⁵R⁶ moiety is a cyclic amino radical,
  • and radicals of the general formulae (IIIa) and (IIIb) with the widest meaning indicated above or the two radicals R¹⁰ are bridges of the general formula (VII) in which G can either be absent or be a carbonyl group or a carbonyl amino group and
  • K is an unsubstituted or substituted C₂-C₄-alkylene chain.
  • R¹ is even more preferably one of the following radicals:
    or a radical of the general formula (VIII)
    where G¹-K-G² together represent (R)-1,2-propanediyl, (S,S)-1,2-cyclohexanediyl, (R,R)-1,2-cyclohexanediyl, 1,2-ethanediyl, 1,3-propanediyl, 1,4-butanediyl or 1,4-dioxobutanediyl or one of the following radicals:
    It may be pointed out at this point that any combinations of the abovementioned preferred meanings of R² with the preferred meanings of R¹ are encompassed by the invention.

The invention encompasses all stereoisomeric compounds of the chiral monophosphorus compounds of the general formula (I), both in pure form and in the form of any mixtures of stereoisomeric compounds, for example racemates or diastereomeric mixtures.

Preferred compounds of the general formula (I) are:

• • (S)-5,5′-dichloro-6,6′-dimethoxy-1,1′-biphenyl-2,2′-diyl isopropyl phosphite,
  • (R)-5,5′-dichloro-6,6′-dimethoxy-1,1′-biphenyl-2,2′-diyl isopropyl phosphite,
  • (R)-5,5′-dichloro-6,6′-dimethoxy-1,1′-biphenyl-2,2′-diyl(R)-1-phenylethyl phosphite,
  • (R)-5,5′-dichloro-6,6′-dimethoxy-1,1′-biphenyl-2,2′-diyl(S)-1-phenylethyl phosphite,
  • (S)-5,5′-dichloro-6,6′-dimethoxy-1,1′-biphenyl-2,2′-diyl(R)-1-phenylethyl phosphite,
  • (S)-5,5′-dichloro-6,6′-dimethoxy-1,1′-biphenyl-2,2′-diyl(S)-1-phenylethyl phosphite,
  • (S)-5,5′-dichloro-6,6′-dimethoxy-1,1′-biphenyl-2,2′-diyl cyclohexyl phosphite,
  • (R)-5,5′-dichloro-6,6′-dimethoxy-1,1′-biphenyl-2,2′-diyl cyclohexyl phosphite,
  • (S)-5,5′-dichloro-6,6′-dimethoxy-1,1′-biphenyl-2,2′-diyl phenyl phosphite,
  • (R)-5,5′-dichloro-6,6′-dimethoxy-1,1′-biphenyl-2,2′-diyl phenyl phosphite,
  • (S)-5,5′-dichloro-6,6′-dimethoxy-1,1′-biphenyl-2,2′-diyl 2,6-dimethylphenyl phosphite,
  • (R)-5,5′-dichloro-6,6′-dimethoxy-1,1′-biphenyl-2,2′-diyl 2,6-dimethylphenyl phosphite,
  • (S)-5,5′,6,6′-tetramethyl-3,3′-bis(tert-butyl)-1,1′-biphenyl-2,2′-diyl isopropyl phosphite,
  • (R)-5,5′,6,6′-tetramethyl-3,3′-bis(tert-butyl)-1,1′-biphenyl-2,2′-diyl isopropyl phosphite,
  • (S)-5,5′,6,6′-tetramethyl-3,3′-bis(tert-butyl)-1,1′-biphenyl-2,2′-diyl(rac)-1-phenyl-ethyl phosphite,
  • (R)-5,5′,6,6′-tetramethyl-3,3′-bis(tert-butyl)-1,1′-biphenyl-2,2′-diyl(rac)-1-phenyl-ethyl phosphite,
  • (S)-5,5′,6,6′-tetramethyl-3,3′-bis(tert-butyl)-1,1′-biphenyl-2,2′-diyl(S)-1-phenyl-ethyl phosphite,
  • (R)-5,5′,6,6′-tetramethyl-3,3′-bis(tert-butyl)-1,1′-biphenyl-2,2′-diyl(S)-1-phenyl-ethyl phosphite,
  • (S)-5,5′,6,6′-tetramethyl-3,3′-bis(tert-butyl)-1,1′-biphenyl-2,2′-diyl(R)-1-phenyl-ethyl phosphite,
  • (R)-5,5′,6,6′-tetramethyl-3,3′-bis(tert-butyl)-1,1′-biphenyl-2,2′-diyl(R)-1-phenyl-ethyl phosphite,
  • (S)-5,5′,6,6′-tetramethyl-3,3′-bis(tert-butyl)-1,1′-biphenyl-2,2′-diyl diphenylmethyl phosphite,
  • (R)-5,5′,6,6′-tetramethyl-3,3′-bis(tert-butyl)-1,1′-biphenyl-2,2′-diyl diphenylmethyl phosphite,
  • (S)-5,5′,6,6′-tetramethyl-3,3′-bis(tert-butyl)-1,1′-biphenyl-2,2′-diyl methyl phosphite,
  • (R)-5,5′,6,6′-tetramethyl-3,3′-bis(tert-butyl)-1,1′-biphenyl-2,2′-diyl methyl phosphite,
  • (S)-5,5′,6,6′-tetramethyl-3,3′-bis(tert-butyl)-1,1′-biphenyl-2,2′-diyl 2,6-dimethyl-phenyl phosphite,
  • (R)-5,5′,6,6′-tetramethyl-3,3′-bis(tert-butyl)-1,1′-biphenyl-2,2′-diyl 2,6-dimethyl-phenyl phosphite,
  • (S)-5,5′,6,6′-tetramethyl-3,3′-bis(tert-butyl)-1,1′-biphenyl-2,2′-diyl 2,6-diisopropylphenyl phosphite,
  • (R)-5,5′,6,6′-tetramethyl-3,3′-bis(tert-butyl)-1,1′-biphenyl-2,2′-diyl 2,6-diisopropylphenyl phosphite,
  • (S)-5,5′,6,6′-tetramethyl-3,3′-bis(tert-butyl)-1,1′-biphenyl-2,2′-diyl phenyl phosphite,
  • (R)-5,5′,6,6′-tetramethyl-3,3′-bis(tert-butyl)-1,1′-biphenyl-2,2′-diyl phenyl phosphite,
  • (S)-5,5′,6,6′-tetramethyl-3,3′-bis(tert-butyl)-1,1 ′-biphenyl-2,2′-diyl ethyl phosphite,
  • (R)-5,5′,6,6′-tetramethyl-3,3′-bis(tert-butyl)-1,1 ′-biphenyl-2,2′-diyl ethyl phosphite
  • (S)-5,5′,6,6′-tetramethyl-3,3′-bis(tert-butyl)-1,1 ′-biphenyl-2,2′-diyl 4-tert-butyl-phenyl phosphite,
  • (R)-5,5′,6,6′-tetramethyl-3,3′-bis(tert-butyl)-1,1 ′-biphenyl-2,2′-diyl 4-tert-butyl-phenyl phosphite.

The chiral monophosphorus compounds of the invention can be prepared in a manner known per se. For example, they can be prepared by

• • reacting diols of the general formula (IX),
    HO—R¹—OH   (IX)
    where R¹ is as defined under the general formula (I),
  • with activated phosphines of the general formula (X)
    (Akt)_nP(R²)_3-n   (X)
    where
  • Akt is chlorine, bromine, iodine, dialkylamino such as dimethylamino or diethylamino and
  • R² is as defined under the general formula (I) and
  • n is 2 or 3,
  • in the presence of a base such as triethylamine or after deprotonation of the starting diol of the general formula (IX).

Akt is preferably chlorine or dimethylamino or diethylamino, particularly preferably chlorine.

If n=3, compounds of the general formula (XI)
are initially formed as intermediates and these can be reacted in a further step with a compound of the general formula (XII)
H—R¹¹   (XII),
where R¹¹ is a radical selected from the group consisting of substituted or unsubstituted alkoxy, substituted or unsubstituted aryloxy and secondary or tertiary amino, with these radicals being defined as under R¹, either in the presence of a base such as triethylamine or after prior deprotonation to give the chiral monophosphorus compounds of the general formula (I).

The compounds of the general formula (XI) are likewise encompassed by the invention.

The separation of stereoisomers can be carried out, for example, by separating biphenyl compounds of the general formula (VI) into the enantiomers by cocrystallization with suitable chiral, enantiomerically enriched auxiliaries, for example chiral enantiomerically pure amines. The preparation of enantiomerically pure biphenols of the general formula (VI) can likewise be carried out by firstly reacting the mixture of stereomeric isomers with a suitable activated phosphorus compound such as PCl₃ or P(NMe₂)₃ (cf. K. Sasse, Methoden der Organischen Chemie, Houben-Weyl, Georg Thieme Verlag, 1964, Vol. XII/2, 4th edition, 5-130) and reacting this product further with an enantiomerically pure alcohol, for example menthol, to produce diastereomeric phosphites which can be separated in a customary fashion and lead after subsequent cleavage to the enantiomerically enriched biphenols of the general formula (VI). Furthermore, compounds of the formula (VI) and of the formula (I) can be separated into their enantiomers by chromatography on chiral stationary phases. Furthermore, enantiomerically pure biphenyl compounds of the formula (VI) can be obtained by reaction with enantiomerically pure biselectrophiles and substituted 2,2′,6,6′-tetrahydroxy-1,1′-biphenyls using a method analogous to that of T. Harada et al. (Organic Letters, 2000, Vol.2, p. 1319).

The invention also encompasses catalysts which comprise transition metal complexes of the novel chiral monophosphorus compounds of the general formula (I). These are, in particular, transition metal complexes of ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium, platinum and copper, preferably those of ruthenium, rhodium, iridium, nickel, palladium, platinum and copper.

As catalysts, it is possible to use, for example, either isolated transition metal complexes or transition metal complexes which are generated from the chiral monophosphorus compounds of the general formula (I) and a metal compound.

Preference is given to using transition metal complexes generated from chiral monophosphorus compounds of the general formula (I) and at least one metal compound as catalysts.

Suitable metal compounds are, by way of example and preferably, those of the general formula
M(Y¹)_p   (XIIIa),
where

• • M is ruthenium, rhodium, iridium, nickel, palladium, platinum or copper and
  • Y¹ is chloride, bromide, acetate, nitrate, methanesulphonate, trifluoromethanesulphonate or acetylacetonate and
  • p is 3 in the case of ruthenium, rhodium and iridium, 2 in the case of nickel, palladium and platinum and 1 in the case of copper,
  • or metal compounds of the general formula (XIIIb)
    M(Y²)_pB¹₂   (XIIIb)
    where
  • M is ruthenium, rhodium, iridium, nickel, palladium, platinum or copper and
  • Y² is chloride, bromide, acetate, methanesulphonate, trifluoromethanesulphonate, tetrafluoroborate, hexafluorophosphate perchlorate, hexafluoroantimonate, tetra(3,5-bistrifluoromethylphenyl)borate or tetraphenylborate and
  • p is 1 in the case of rhodium and iridium, 2 in the case of nickel, palladium, platinum and ruthenium and 1 in the case of copper,
  • B¹ are each a C₂-C₁₂-alkene such as ethylene or cyclooctene, or a nitrile such as acetonitrile, benzonitrile or benzyl nitrile, or
  • the B¹₂ moiety is a (C₄-C₁₂)-diene such as norbornadiene or 1,5-cyclooctadiene,
  • or metal compounds of the general formula (XIIIc)
    [MB²Y¹₂]₂   (XIIIc),
    where
  • M is ruthenium and
  • B² is an aryl radical such as cymene, mesityl, phenyl or cyclooctadiene, norbornadiene or methylallyl,
  • or metal compounds of the general formula (XIIId)
    Me_p[M(Y³)₄]  (XIIId),
    where
  • M is palladium, nickel, iridium or rhodium and
  • Y³ is chloride or bromide and
  • Me is lithium, sodium, potassium, ammonium or organic ammonium and
  • is 3 in the case of rhodium and iridium and 2 in the case of nickel, palladium and platinum,
  • or metal compounds of the general formula (XIIIe)
    [M(B³)₂]An   (XIIIe),
    where
  • M is iridium or rhodium and
  • B³ is a (C₄-C₁₂)-diene such as norbornadiene or 1,5-cyclooctadiene and
  • An is a noncoordinating or weakly coordinating anion such as methanesulphonate, trifluoromethanesulphonate, tetrafluoroborate, hexafluorophosphate perchlorate, hexafluoroantimonate, tetra(3,5-bistrifluoromethylphenyl)borate or tetraphenylborate.

Further suitable metal compounds are, for example, Ni(1,5-cyclooctadiene)₂, Pd₂(dibenzylideneacetone)₃, Pd[PPh₃]₄, cyclopentadienyl₂Ru, Rh(acac)(CO)₂, Ir(pyridine)₂(1,5-cyclooctadiene), Cu(phenyl)Br, Cu(phenyl)Cl, Cu(phenyl)I, Cu(PPh₃)₂Br, [Cu(CH₃CN)₄]BF₄ and [Cu(CH₃CN)₄]PF₆ or multinuclear bridged complexes such as [Rh(1,5-cyclooctadiene)Cl]₂ and [Rh(1,5-cyclooctadiene)Br]₂, [Rh(ethene)₂Cl]₂, [Rh(cyclooctene)₂Cl]₂.

Preference is given to using the following metal compounds:

• • [Rh(COD)Cl]₂, [Rh(COD)₂Br], [Rh(COD)₂]ClO₄, [Rh(COD)₂]BF₄, [Rh(COD)₂]PF₆, [Rh(COD)₂]OTf, [Rh(COD)₂]BAr₄ (Ar=3,5-bistrifluoromethylphenyl)[Rh(COD)₂]SbF₆ RuCl₂(COD), [(cymene)RuCl₂]₂, [(benzene)RuCl₂]₂, [(mesityl)-RuCl₂]₂, [(cymene)RuBr₂]₂, [(cymene)RuI₂]₂, [(cymene)Ru(BF₄)₂]₂, [(cymene)-Ru(PF₆)₂]₂, [(cymene)Ru(BAr₄)₂]₂, (Ar=3,5-bistrifluoromethylphenyl), [(cymene)-Ru(SbF₆)₂]₂, [Ir(cod)₂Cl]₂, [Ir(COD)₂]PF₆, [Ir(COD)₂]ClO₄, [Ir(COD)₂SbF₆ [Ir(COD)₂]BF₄, [Ir(COD)₂]OTf, [Ir(COD)₂]BAr₄ (Ar=3,5-bistrifluoromethylphenyl), RuCl₃, NiCl₂, RhCl₃, PdCl₂, PdBr₂, Pd(OAc)₂, Pd₂(dibenzylideneacetone)₃, Pd(acetylacetonate)₂, CuOTf, Cul, CuCl, Cu(OTf)₂, CuBr, CuI, CuBr₂, CuCl₂, CuI₂,
  • [Rh(nbd)Cl]₂, [Rh(nbd)₂Br], [Rh(nbd)₂]ClO₄, [Rh(nbd)₂]BF₄, [Rh(nbd)₂]PF₆, [Rh(nbd)₂]OTf, [Rh(nbd)₂]BAr₄ (Ar=3,5-bistrifluoromethylphenyl) [Rh(nbd)₂]SbF₆ RuCl₂(nbd), [Ir(nbd)₂]PF₆, [Ir(nbd)₂]ClO₄, [Ir(nbd)₂]SbF₆ [Ir(nbd)₂]BF₄, [Ir(nbd)₂]OTf, [Ir(nbd)₂]BAr₄ (Ar=3,5-bistrifluoromethylphenyl), Ir(pyridine)₂(nbd), [Ru(DMSO)₄Cl₂], [Ru(CH₃CN)₄Cl₂], [Ru(PhCN)₄Cl₂], [Ru(COD)Cl₂]_n, [Ru(COD)(methallyl)₂], [Ru(acetylacetonate)₃]

Even greater preference is given to Rh(COD)₂ trifluoromethanesulphonate, Rh(nbd)₂PF₆ and Rh(nbd)₂BF₄.

The amount of metal compound used can be, for example, from 25 to 200 mol % based on the chiral monophosphorus compound of the general formula (I) which is used, preferably from 30 to 100 mol %, very particularly preferably from 40 to 60 mol % and even more preferably from 45 to 55 mol %.

The catalysts comprising transition metal complexes generated in situ or isolated transition metal complexes are suitable, in particular, for use in a process for preparing chiral compounds.

The catalysts are preferably used for asymmetric 1,4-additions, asymmetric hydroformylations, asymmetric hydrocyanations, asymmetric Heck reactions and asymmetric hydrogenations, particularly preferably asymmetric hydrogenations. Preferred asymmetric hydrogenations are, for example, hydrogenations of prochiral C═C bonds, for example prochiral enamines, olefins, enol ethers, C═O bonds, for example prochiral ketones, and C═N bonds, for example prochiral imines. Particularly preferred asymmetric hydrogenations are hydrogenations of prochiral enamines and olefins.

The amount of metal compound used or of transition metal complex used can be, for example, from 0.001 to 5 mol % based on the substrate used, preferably from 0.001 to 0.5 mol %, very particularly preferably from 0.001 to 0.1 mol % and even more preferably from 0.001 to 0.008 mol %.

In a preferred embodiment, asymmetric hydrogenations can be carried out, for example, by generating the catalyst in situ from a metal compound and a chiral monophosphorus compound of the general formula (I) in the presence or absence of a suitable solvent, adding the substrate and placing the reaction mixture under hydrogen pressure at the reaction temperature.

As metal compounds for asymmetric hydrogenations, preference is given to using compounds of the general formula (XIIIe)
[M(B³)₂]An   (XIIIe),
where

• • M is rhodium and
  • B³ is a (C₄-C₁₂)-diene such as norbornadiene or 1,5-cyclooctadiene and
  • An is a noncoordinating or weakly coordinating anion such as methane-sulphonate, trifluoromethanesulphonate, tetrafluoroborate, hexafluorophosphate, perchlorate, hexafluoroantimonate, hexachloroantimonate, tetra(3,5-bistrifluoromethylphenyl)borate or tetraphenylborate or
  • binuclear complexes such as [Rh(1,5-cyclooctadiene)Cl]₂ and [Rh(1,5-cyclo-octadiene)Br]₂, [Rh(ethene)₂Cl]₂, [Rh(cyclooctene)₂Cl]₂.

Particularly preferred metal compounds for asymmetric hydrogenations are [Rh(1,5-cyclooctadiene)₂]BF₄, [Rh(1,5-cyclooctadiene)₂]PF₆, [Rh(norbornadiene)₂]PF₆ and [Rh(norbornadiene)₂]BF₄.

In a particularly preferred embodiment, metal compound and monophosphorus compound are dissolved in a degassed solvent in a baked-out glass autoclave. The mixture is stirred for about 5 minutes and the substrate in a degassed solvent is subsequently added. After setting the appropriate temperature, the hydrogenation is carried out under H₂ pressure.

Suitable solvents for the asymmetric hydrogenation are, for example, chlorinated alkanes such as methylene chloride, short-chain C₁-C₆-alcohols such as methanol, isopropanol or ethanol, aromatic hydrocarbons such as toluene or benzene, ketones such as acetone or carboxylic esters such as ethyl acetate.

The asymmetric hydrogenation is carried out, for example, at a temperature of from −20° C. to 200° C., preferably from 0 to 100° C. and particularly preferably from 20 to 70° C.

The hydrogen pressure can be, for example, from 0.1 to 200 bar, preferably from 0.5 to 50 bar and particularly preferably from 0.5 to 5 bar.

The catalysts of the invention are particularly suitable for processes for preparing chiral active compounds in pharmaceuticals and agrochemicals, or intermediates for these two classes.

The advantage of the present invention is that activities of far above 1 000 h⁻¹ (TOF) which have hitherto not been achieved can be achieved using ligands which are simple to prepare, in particular in asymmetric hydrogenations.

The invention is further illustrated but is not intended to be limited by the following examples in which all parts and percentages are by weight unless otherwise specified.

EXAMPLES Example 1 Synthesis of (S)-5,5′-dichloro-6,6′-dimethoxy-1,1′-biphenyl-2,2′-dioxy)chlorophosphane

A solution of 1 g (3.17 mmol) of (S)—Cl-MeO-biphenol is added dropwise to a mixture of 0.41 ml (4.12 mmol) of PCl₃ and 0.97 ml (6.98 mmol) of NEt₃ in 5 ml of THF while cooling in ice. The mixture is stirred at RT for 1 hour, the precipitate which has formed is filtered off and is washed with a little solvent. Removal of the solvent gives the product as a yellowish oil.

¹H-NMR (CDCl₃): δ [ppm]=3.57 (s, 3H, OCH₃); 3.59 (s, 3H, OCH₃); 6.92 (d, ³J=8.7, 1H, H_{b or b′}); 7.01 (dd, 1H, ³J=8.7, J(H-P)=1.1, 1H, H_{b or b′}); 7.46 (br d, ³J=8.7, 2H, H_{a and a′}); ³¹P-NMR (CDCl₃): δ [ppm]=176.4

Examples 2-6 Synthesis of (S)-phosphites

3.17 mmol of the appropriate alcohol (i-propanol, cyclohexanol, (R)-1-phenyl-ethanol, phenol, 2,6-dimethylphenol) are dissolved in 5 ml of THF and admixed with 0.44 ml (3.17 mmol) of NEt₃. 1.204 g (3.17 mmol) of phosphochloridite from Example 1, dissolved in 10 ml of THF, are added dropwise at 0° C. After 1 hour, the precipitate which has formed is filtered off and is washed with a little THF. Removal of the solvent gives the phosphites as white to slightly yellowish solids or oils.

Example 2 (S)-5,5′-Dichloro-6,6′-dimethoxy-1,1′-biphenyl-2,2′-diyl isopropyl phosphite

¹H-NMR (CDCl₃): δ [ppm]=1.29 (d, ³J=6.2, 3H, CH₃), 1.33 (d, ³J=6.2, 3H, CH₃); 3.53 and 3.54 (s, 3H, OCH₃); 4.53 (dsep, ³J=6.2, J(H-P)=9.0, 1H, CH); 6.83 (dd, ³J=8.7, J(H-P)=0.8, 1H, H_{b or b′}); 6.96 (dd, ³J=8.7, J(H-P)=1.2, 1H, H_{b or b′}); 7.37 (d, ³J=8.7, 1H, H_{a or a′}); 7.40 (dd, ³J=8.7, J(H-P) =0.5, 1H, H_{a or a′}); ³¹P-NMR (CDCl₃): δ [ppm]=145.3

Example 3 (S)-5,5′-Dichloro-6,6′-dimethoxy-1,1′-biphenyl-2,2′-diyl cyclohexyl phosphite

¹H-NMR (CDCl₃): δ [ppm]=1.00-2.00 (kB, 10H, CH₂); 3.53 and 3.54 (s, 3H, OCH₃); 4.19 (dsep, J=4.5, J(H-P)=9.1, 1H, CH); 6.83 (dd, ³J=8.7, J(H-P)=0.7, 1H, H_{b or b′}); 6.96 (dd, ³J=8.7, J(H-P)=1.1, 1H, H_{b or b′}); 7.36 (d, ³J=8.7, 1H, H_{a or a′}); 7.40 (d, ³J=8.7, 1H, H_{a or a′}); ³¹P-NMR (CDCl₃): δ [ppm]=146.1

Example 4 (S)-5,5′-Dichloro-6,6′-dimethoxy-1,1′-biphenyl-2,2′-diyl(R)-1-phenylethyl phosphite

¹H-NMR (CDCl₃): δ [ppm]=1.59 (d, ³J=6.5, 3H, CH₃); 3.49 and 3.53 (s, 3H, OCH₃); 5.38 (dq, ³J=6.5, J(H-P) =9.4, 1H, CH); 6.17 (dd, ³J =8.7, J(H-P)=0.7, 1H, H_{b or b′}); 6.95 (dd, ³J=8.7, J(H-P)=1.1, 1H, H_{b or b′}); 7.21 (d, ³J=8.7, 1H, H_{a or a′}); 7.25-7.38 (kB, 5H, H_arom); 7.38 (d, ³J=8.7, 1H, H_{a or a′}); ³¹P-NMR (CDCl₃): δ [ppm]=146.9

Example 5 (S)-5,5′-Dichloro-6,6′-dimethoxy-1,1′-biphenyl-2,2′-diyl phenyl phosphite

¹H-NMR (CDCl₃): δ [ppm]=3.59 and 3.61 (s, 3H, OCH₃); 6.90 (dd, ³J=8.7, J(H-P)=0.6, 1H, H_{b or b′}); 7.06 (dd, ³J=8.7, J(H-P)=1.1, 1H, H_{b or b′}); 7.13-7.21 (kB, 3H, H-2 and H-4); 7.32-7.38 (kB, 2H, H-3); 7.40 (d, ³J=8.7, 1 H, H_{a or a′}); 7.47 (d, ³J=8.7, 1H, H_{a or a′}); ³¹P-NMR (CDCl₃): δ [ppm]=141.4

Example 6 (S)-5,5′-Dichloro-6,6′-dimethoxy-1,1′-biphenyl-2,2′-diyl 2,6-dimethylphenyl phosphite

¹H-NMR (CDCl₃): δ [ppm]=2.40 (s, 6H, CH₃), 3.61 (s, 6H, OCH₃); 7.02 (dd, ³J=8.7, J(H-P)=1.0, 1H, H_{b or b′}); 7.02-7.12 (kB, 3H, H_arom); 7.03 (dd, ³J=8.7, J(H-P)=0.8, 1H, H_{b or b′}); 7.45 (d, ³J=8.7, 1H, H_{a or a′}); 7.46 (d, ³J=8.7, 1H, H_{a or a′}); ³¹P-NMR (CDCl₃): δ [ppm]=145.1

Hydrogenations

Examples 7-11 Hydrogenation of Dimethyl Itaconate

In a baked-out glass autoclave, 0.02 mmol of bis(norbornadiene)rhodium(I) tetrafluoroborate [Rh(nbd)₂]BF₄ and 0.04 mmol of the appropriate phosphite are dissolved in 5 ml of degassed methylene chloride. The mixture is stirred for about 5 minutes and 8 mmol of dimethyl itaconate and 0.2000 g of diglyme in 15 ml of degassed methylene chloride are subsequently added. After setting the appropriate temperature, the mixture is hydrogenated for 2 hours under a hydrogen partial pressure of 0.5 bar. Conversion and ee are determined by gas chromatography.

The results are summarized in Table 1.

	TABLE 1
	Conversion	ee [%],
	[%]	configuration

Example	Ligand (configuration)	RT	0° C.	RT	0° C.

7	R = i-Propyl (S) from	100	100	96 (S)	97 (S)
	Example 2
8	R = Cyclohexyl (S) from	100	100	91 (S)	94 (S)
	Example 3
9	R = (R)-1-Phenylethyl (S)	100	100	97 (S)	99 (S)
	from Example 4
10	R = Phenyl (S) from	100	87	82 (S)	91 (S)
	Example 5
11	R = 2,6-Dimethylphenyl	58	41	59 (S)	74 (S)
	(S) from Example 6

Example 12-13 Hydrogenation of Dimethyl Itaconate

In a baked-out glass autoclave, 0.02 mmol of bis(bicyclo[2.1.1]hepta-2,5-diene)rhodium(I) tetrafluoroborate[Rh(nbd)₂]BF₄ and 0.04 mmol of the appropriate phosphite are dissolved in 50 ml of degassed methylene chloride. The mixture is stirred for about 5 minutes and 200 mmol of dimethyl itaconate and 5.000 g diglyme in 250 ml of degassed methylene chloride are subsequently added. After setting the appropriate temperature, the mixture is hydrogenated for 2.5 hours under a hydrogen partial pressure of 0.5 bar. Conversion and ee are determined by gas chromatography.

The results are summarized in Table 2.

TABLE 2
		Conversion	ee [%],
Example	Ligand (configuration)	[%]	configuration

12	R = i-Propyl (S) from Example	90	97 (S)
	2
13	R = (R)-1-Phenylethyl (S) from	100	99 (S)
	Example 4

Example 14-18 Hydrogenation of methyl 2-acetamidoacrylate

0.0024 mmol of the appropriate phosphite are weighed out and admixed under argon with a solution of 0.0012 mmol of bis(norbornadiene)rhodium(I) hexafluorophosphate [(nbd)₂Rh]PF₆ and 0.12 mmol of methyl 2-acetamidoacrylate in 0.8 ml of degassed CH₂Cl₂. The mixture is subsequently hydrogenated for 23 hours under a hydrogen pressure of 3 bar.

The results are summarized in Table 3.

TABLE 3
		Conversion	ee [%],
Examples	Ligand (configuration)	[%]	configuration
14	R = I-Propyl (S) from	100	94 (R)
	Example 2
15	R = Cyclohexyl (S) from	100	94 (R)
	Example 3
16	R = (R)-1-Phenylethyl (S) from	100	83 (R)
	Example 4
17	R = Phenyl (S) from Example 5	100	77 (R)
18	R = 2,6-Dimethylphenyl (S)	100	18 (R)
	from Example 6

Example 19-20 Hydrogenation of methyl cis-3-acetamidobutenoate

0.0024 mmol of the appropriate phosphite are weighed out and admixed under argon with a solution of 0.0012 mmol of bis(bicyclo[2.1.1]hepta-2,5-diene)rhodium(I) hexafluorophosphate[Rh(nbd)₂]BF₄ and 0.12 mmol of methyl cis-3-acetamidobutenoate in 0.8 ml of degassed CH₂Cl₂. The mixture is subsequently hydrogenated for 23 hours under a hydrogen pressure of 3 bar.

The results are summarized in Table 4.

TABLE 4
Examples	Ligand (configuration)	Conversion [%]	ee [%]
19	R = i-Propyl (S) (Ex. 2)	4	71
20	R = Cyclohexyl (S) (Ex. 3)	3	56 (other
			enantiomer)

Example 21-29 Synthesis of 3,3′-bis(1,1-dimethylethyl)-5,5′,6,6′-tetramethyl-1,1′-biphenyl-2,2′-diol phosphites (BIPHEN phosphites)

In a 250 ml Schlenk flask which had been baked out and flushed with argon three times, 70 ml of toluene and 1.9 ml (0.0137 mol) of triethylamine were cooled to −78° C. (dry ice/acetone). 0.3 ml (0.0034 mol) of phosphorus trichloride was added while stirring vigorously. 1 g (0.0028 mol) of solid (R)- or (S)-BIPHEN was added to this slightly turbid suspension in a countercurrent of argon over a period of 2-3 hours by means of a powder feed device. A white or yellow suspension was formed and this was warmed to room temperature overnight. The mixture was subsequently filtered through an inversion frit under protective gas and the solvent was removed under reduced pressure. This gave a yellow or white solid.

A solution of about 3 mmol (1 eq, 1.1 g) of this solid was added to 41 ml of toluene, 0.43 ml (3 mmol, 1 eq) of triethylamine and the amount of alcohol indicated in the table (Examples 21 to 29). The solution was stirred under argon overnight at room temperature. The mixture was subsequently filtered through an inversion frit to remove the ammonium salt and the solvent was removed under reduced pressure. This gave a yellow or white solid.

The yields and physical data are summarized in Table 5.

TABLE 5
	Amount of
Example:	alcohol	Yield	Analysis
21	0.26 g (0.0028	0.911 g (68%)	31P NMR: δ = 135.29
	mol) of phenol	of yellow solid	ppm
22	0.15 ml (0.0028	0.802 g (67%)	31P NMR: δ = 132.45
	mol; 1 eq) of	of white solid	ppm
	ethanol
231)	0.34 g (0.0028	1.353 g (95%)	31P NMR: δ = 135.77
	mol; 1 eq) of 2,6-	of white solid	ppm
	dimethylphenol
	0.14 g (0.0058
	mol; 1,1 eq) of
	sodium hydride
24	0.11 ml (0.0028	1.151 g (99%)	31P NMR δ = 130.18
	mol; 1 eq) of	of white solid	ppm
	methanol
25	0.424 ml (0.0028	0.978 g (65%)	31P NMR δ = 136.3
	mol; 1 eq) of tert-	of yellow solid	ppm
	butylphenol
26	0.34 ml (0.0028	0.881 g (62%)	31P NMR δ = 141.82
	mol; 1 eq) of	of whitish	ppm and 138.58 (dia-
	phenylethyl	yellow solid	stereomeric pair)
	alcohol
27	0.52 g (0.0028	0.771 g (48%)	31P NMR δ = 136.35
	mol; 1 eq) of	of white solid	ppm
	diphenyl carbinol
28	0.22 ml (0.0028	0.521 g (33%)	31P NMR: δ 142.84
	mol; 1 eq) of	of white solid	ppm
	isopropanol
291)	Five-fold batch	7.23 g (92%)	31P NMR: δ 1365.74
	using 8.1 ml	of yellow solid	ppm
	(0.014 mol; 1 eq)
	of 2,6-
	diisopropylphenol
1)Additional use of sodium hydride as base to form the phenoxide

Examples 30 to 33 Asymmetric Hydrogenation Using BIPHEN Phosphites

The ligands (from Examples 21 and 24) were weighed into the reaction vessels (batch size: 0.09 mmol). The substrates were subsequently each prepared as a stock solution (dilution: 0.13 mol/l) in 5.1 ml of methylene chloride and degassed. 5.6 mg of bis-(1,5-cycloctadiene)rhodium triflate Rh(COD)₂OTf were in each case added and the mixture was degassed again. In a glove box, 0.72 ml of solution was placed in each of the individual vessels (2 mol % of catalyst and 2 mol % of ligand). All batches were hydrogenated in an autoclave (23 h, 3 bar of hydrogen pressure, RT).

The results are summarized in Tables 6 and 7.

TABLE 6
Hydrogenation of methyl cis-3-acetamidobutenoate

	Ligand	21	24

	Conversion [%]	100	100
	ee [%]	11.3	59
	Example No.	30	31

TABLE 7
Hydrogenation of dimethyl itaconate

	Ligand	21	24

	Conversion [%]	100	100
	ee [%]	14	13
	Example No.	32	33

Although the invention has been described in detail in the foregoing for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be limited by the claims.