Process for the asymmetric hydrogenation of carbonyl compounds o

Details Process for the asymmetric hydrogenation of carbonyl compounds o Process for the asymmetric hydrogenation of carbonyl compounds o

1990-04-27

1992-07-07

Robinson, Allen J.

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

564170, 568700, 568880, 568814, 568388, C07D30760, C07C23536

Patent

active

051284880

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to the enantioselective synthesis of organic compounds and it relates more particularly to the asymmetric hydrogenation of carbonyl groups, catalyzed by transition metal complexes containing chiral phosphorus-containing ligands.
Although a reduction catalysed in a homogeneous phase by Wilkinson type complexes, Rh[PPh.sub.3 ].sub.3 Cl, prove to be very effective with respect to the asymmetric synthesis of .alpha.-amino acids from olefinic precursors (H. B. Kagan, "Asymmetric synthesis using organometallic catalysts, Comprehensive organometallic chemistry, G. Wilkinson Ed. (1982) Vol. 8, 463, Pergamon Press, London), it is inoperative, however, in the synthesis of chiral alcohols from ketones.
Moreover, in asymmetric catalysis, it is well known that the different types of ligands are specific for a given starting compound (substrate).
It has now been discovered that asymmetric hydrogenation of carbonyl compounds could be envisaged with excellent results by the use of ligands obtained in a single stage starting with chiral .alpha.-amino alcohols which are commercially produced or which are derived from natural .alpha.-amino acids, such ligands having already been described in European Patent Application EP-A-136,210 for other syntheses (such as asymmetric hydrogenation of dehydroamino acids) and by M. Petit, A. Mortreux, F. Petit, G. Buono and G. Peiffer in "Nouv. J. chim. 10 (7) (1983) 593".
Moreover, it has surprisingly been discovered that the choice of a reaction medium in which the substrate is soluble whereas the final product is insoluble enables, on the one hand, high optical yields to be achieved and, on the other hand, very high substrate:metal catalyst molar ratios (which may range up to 5000) to be employed, which has never been possible to achieve until now. Thus, these ratios are 50 and 200 in the case of the asymmetric hydrogenations of the carbonyl group, described by K. Yamamoto et al. and by K. Tani et al. respectively, the value 200 representing the upper limit which could be achieved so far.
The subject of the present invention is a process for the asymmetric hydrogenation of carbonyl compounds, which is carried out in the presence, on the one hand, of at least one transition metal complex of formula: complexing the metal M; and wherein a compound represented by formula (I) is chosen as the chiral phosphorus-containing ligand: ##STR2## in which formula: R represents a hydrocarbon radical chosen from amongst straight-chain or branched alkyl, cycloalkyl or aryl radicals; residue; amongst hydrogen atoms and hydrocarbon radicals optionally carrying at least one group chosen from amongst alcohol, thiol, thioether, amine, imine, acid, ester, amide and ether groups; and functionalized hydrocarbon radicals; --OPR.sub.2 or --NPR.sub.2 group, both R.sup.5 and R.sup.6 being, in this case, equal to hydrogen when R.sup.1 represents --PR.sub.2, which carry them respectively to together form a heterocycle; and carbon atoms which carry them respectively and the intermediate carbon atoms to together form a heterocycle.
This family of ligands may be divided into three sub-families depending on the number of dihydrocarbylphosphine (--PR.sub.2) radicals present, i.e. monodentate chelates (in which R.sup.1 does not refer to --PR.sub.2 and R.sup.3 does not carry the residue --OPR.sub.2 or --NPR.sub.2); bidentate chelates (in which either R.sup.1 represents --PR.sub.2 in which case R.sup.3 and R.sup.4 do not carry a --OPR.sub.2 or --NPR.sub.2 group, or R.sup.3 or R.sup.4 carry an --OPR.sub.2 or --NPR.sub.2 residue in which case R.sup.1 cannot represent --PR.sub.2) and tridentate chelates (in which R.sup.1 represents a --PR.sub.2 residue and R.sup.3 carries an --OPR.sub.2 or --NPR.sub.2 residue).
As alkyl radicals for R, there will be mentioned C.sub.1 -C.sub.12, especially C.sub.1 -C.sub.6, alkyl radicals, for example methyl, ethyl, isopropyl and tert-butyl radicals. As cycloalkyl radicals for R, there will be mentioned cyclopentyl and cyclohexyl radicals. As aryl radicals for R, th

REFERENCES:
patent: 3968147 (1976-07-01), Solodar
patent: 4539411 (1985-09-01), Broger et al.
patent: 4556740 (1985-12-01), Hansen et al.
M. Petit et al., Nouveau Journal De Chemie, vol. 7, No. 10, pp. 593-96, 1983.
H. B. Kagan, "Asymmetric Synthesis Using Organometallic Catalysts," Comprehensive Organometallic Chemistry, G. Wilinson, Ed. (1982) vol. 8, Pergamon Press, London, pp. 463-498.
K. Tani, "Preparation of New Chiral Peralkyldiphosphines as Efficient Ligands for Catalytic Asymmetric Hydrogenation of .alpha.-Dicarbonyl Compounds", J. Chem. Soc., Chem. Commun., 1984, pp. 1641-1643.

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