Organic compounds -- part of the class 532-570 series – Organic compounds – Heavy metal containing
Patent
1997-07-09
1998-06-02
Nazario-Gonzalez, Porfirio
Organic compounds -- part of the class 532-570 series
Organic compounds
Heavy metal containing
502162, 556144, 556148, C07F 1702, C07F 1502, B01J 3100
Patent
active
057602646
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a process for preparing optically active metallocenylphosphines from prochiral acylmetallocenes.
BACKGROUND OF THE ART
Optically active phosphines are being used to an increasing extent as ligands for chiral transition metal complexes. The latter are in turn used as catalysts in homogeneously catalyzed enantioselective reactions ("asymmetric syntheses").
Optically active phosphines used include, in particular, metallocenylphosphines having chiral substituents on the cyclopentadiene ring. An important group of such metallocenylphosphines is represented by the general formulae ##STR1## and their mirror images.
In these formulae, M is iron, ruthenium or nickel; R.sup.1 and R.sup.1' are identical or different and are each a C.sub.1 -C.sub.4 -alkyl group, a C.sub.1 -C.sub.4 -perfluoroalkyl group, a C.sub.2 -C.sub.4 -alkenyl group, a C.sub.3 -C.sub.6 -cycloalkyl group or an unsubstituted or substituted acyl group; R.sup.2 and R.sup.3 are either, independently of one another, hydrogen or a C.sub.1 -C.sub.4 -alkyl group or together with the nitrogen atom form a five- or six-membered saturated heterocyclic ring which may also contain further heteroatoms; R.sup.4 and R.sup.5 are each, independently of one another, a C.sub.1 -C.sub.4 -alkyl group, a C.sub.3 -C.sub.6 -cycloalkyl group or an aryl group which may be unsubstituted or substituted by one or more methyl or methoxy groups or by one or more fluorine atoms, or R.sup.4 and R.sup.5 together with the phosphorus atom form a saturated five- or six-membered heterocyclic ring. Here and in the following, C.sub.1 -C.sub.4 -alkyl groups are in each case unbranched and branched primary, secondary and tertiary alkyl groups having up to four carbon atoms, i.e. methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl and tert-butyl. C.sub.1 -C.sub.4 -Perfluoroalkyl groups are the corresponding perfluorinated groups, preferably trifluoromethyl. C.sub.2 -C.sub.4 -Alkenyl groups are, for example, vinyl, allyl, propenyl, 1-butenyl, 2-butenyl, 3-butenyl and isopropenyl; C.sub.3 -C.sub.6 -cycloalkyl is cyclopropyl, cyclobutyl, cyclopentyl and preferably cyclohexyl. Aryl groups are monocyclic and polycyclic aromatic hydrocarbon radicals, in particular phenyl and naphthyl. Examples of such metallocenylphosphines and their use may be found, inter alia, in T. Hayashi et al., Bull. Chem. Soc. Jpn. 1980, 53, 1138-1151 (M.dbd.Fe).
The compounds of the formulae Ia and Ib each contain not only the chiral centre at the carbon atom adjacent to R.sup.1 but also a chiral plane through the 1,2-disubstituted cyclopentadiene ring. However, among the possible stereoisomers, the introduction of the phosphino group forms only those in which both chirality elements have the opposite configuration, i.e. the (R.sup.*,S.sup.*) stereoisomers according to the convention employed in Chemical Abstracts. Here and in the following, the S--(R.sup.*,S.sup.*) stereoisomer, in which the absolute configuration in respect of the chiral plane is S, is depicted in each case.
If the two substituents R.sup.4 and R.sup.5 on the phosphorus atom are different, the latter forms an additional chiral centre.
The previous processes for preparing the optically active metallocenylphosphines of the formula I (see, for example, B. T. Hayashi et al., loc. cit.) generally require racemate resolution of a precursor (cf. D. Marquarding et al., J. Am. Chem. Soc. 1970, 92, 5389).
This racemate resolution requires not only a considerable outlay, but also reduces the yield because, as a rule, only one of the two enantiomers is required and the other may be regarded as waste.
BROAD DESCRIPTION OF THE DESCRIPTION
It is an object of the present invention to open up a route to the optically active metallocenylphosphines of the formula Ia/lb which does without racemate resolution and makes it possible to prepare the S--(R.sup.*,S.sup.*) stereoisomer depicted or its mirror image as required in a targeted manner.
According to the invention, this o
REFERENCES:
Hayashi et al., J. Organomet. Chem., vol. 370, Nos. 1 to 3 (1989) pp. 129 to 139.
Marquarding et al., J. Am. Chem. Soc., vol. 92, No. 18, (1970), pp. 5389 to 5393.
C. R. Hauser and J. K. Lindsay, J. Am. Chem., (1957), 22, 482.
Lambusta et al., Tetrahedron: Asymmetry, vol. 4, (5) pp. 919-924.
Hayashi et al., Bull. Chem. Soc. Jpn., vol. 4, No. 5, (1980), pp. 1138-1151 .
Lonza AG
Nazario-Gonzalez Porfirio
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