Process for producing optically active threo-dihydroxyphenylserine derivatives.

摘要

Optically active threo-dihydroxyphenylserine derivatives represented by the forumla: wherein R1 and R2 each represents or form together a protecting group for the phenolic hydroxyl group, R3 represents a protecting group for the amino group and R4 represents a protecting group for the carboxyl group, which are intermediates for L-threo-3-(3,4-dihydroxyphenyl)-serine, are prepared by asymmetrical hydrogenation of ketones represented by the formula: wherein R1, R2, R3 and R4 are as defined above, in a solvent in the presence of optically active ruthenium phosphine complexes represented by the formula: wherein X represents a chlorine atom, a bromine atom or an acetoxy group, R5 represents a lower alkyl group of 1 - 5 carbon atoms, Z represents a phenyl group or a p-tolyl group and n is 0 or 1.