Process for preparing optically active carnitine ester

摘要

A process for preparing an optically active carnitine ester represented by formula (I):wherein R represents a lower alkyl group; and X represents a halogen atom,is disclosed, comprises asymmetrically hydrogenating a gamma-trimethylammonium-3-oxobutanoic ester halide represented by formula (II):wherein R and X are as defined above,in the presence of a ruthenium-optically active phosphine complex as a catalyst. An optically active carnitine ester of any desired isomerism can be obtained through simple operation in high yield at high optical purity. The substrate used is easily available.