Patent ID: 6583312
Filing Date: 2003-06-24
Classification: C07C

Abstract:
A process for preparing optically active trimethyllactic acid and/or esters thereof having formula (I) wherein R1 represents hydrogen, alkyl, aryl, aralkyl, or heterocyclyl, comprising enatiomerically hydrogenating trimethylpyruvic acid and/or esters thereof having formula (II) â€ƒwherein R1 has the meanings specified for formula (I), in the presence of a catalyst comprising one or more noble metal complexes containing optically active bisphosphines as ligands selected from the group consisting of (1) a bisphosphine of formula (B1) â€ƒwhere R2 denotes phenyl, 3-methylphenyl, 4-methylphenyl, 3,5-dimethylphenyl, 4-methoxyphenyl, 3,5-dimethyl-4-methoxyphenyl, cyclohexyl, or cyclopentyl, or (2) a bisphosphine of formula (B2) â€ƒwhere R3 denotes phenyl, 4-methylphenyl, 3,5-dimethylphenyl, 4-methoxyphenyl, 3,5-dimethyl-4-methoxyphenyl, or cyclohexyl, or (3) a bisphosphine of formula (B3) â€ƒwhere R3 denotes phenyl, 4-methylphenyl, 3,5-dimethylphenyl, 4-methoxyphenyl, 3,5-dimethyl-4-methoxyphenyl, or cyclohexyl, R4 denotes H, methyl, or methoxy, R5 denotes H, methyl, methoxy, or chlorine, and R6 denotes methyl, methoxy, or trifluoromethyl, or (4) a bisphosphine of formula (B4) â€ƒwhere R7 represents methyl, ethyl, propyl, or isopropyl, or (5) 2,3-bis(diphenylphosphino)butane of formula (B5) (6) 1,2-bis(diphenylphosphino)propane of formula (B6) (7) 5,6-bis(diphenylphosphino)-2-norbornane of formula (B7) (8) 1-substituted 3,4-bis(diphenylphosphino)pyrrolidine of formula (B8) (9) 2,4-bis(diphenylphosphino)pentane of formula (B9) (10) 2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino)butane of formula (B10) (11) 1,2-bis-[(o-methoxyphenyl)phenylphosphino]ethane of formula (B11) (12) 1-[1â€²,2-bis(diphenylphosphino)ferrocenyl]ethanol of formula (B12) (13) 1-tert-butoxycarbonyl-4-diphenylphosphino-2-diphenylphosphinomethyl-pyrrolidine of formula (B13) (14) a bisphosphine of formula (B14) â€ƒwhere R8 denotes phenyl, cyclohexyl, 4-methylphenyl, 4-methoxyphenyl, 3,5-dimethylphenyl, 3,5-dimethyl-4-methoxyphenyl, 4-tert-butyl, or 3,5-di-tert-butyl, or (15) a ferrocenyldiphosphine of formula (B15) â€ƒwhere R8 denotes phenyl, cyclohexyl, 4-methylphenyl, 4-methoxyphenyl, 3,5-dimethylphenyl, 3,5-dimethyl-4-methoxyphenyl, 4-tert-butyl, or 3,5-di-tert-butyl, and R9 denotes C1-C8-alkyl, phenyl, or phenyl monosubstituted to trisubstituted by C1-C4-alkoxy.