Patent ID: 8143052

Claim:
A process for preparing an optically active (S or R)-α-amino acid represented by the formula (II): wherein R represents an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an aralkyl group, a heteroarylalkyl group, an aryl group or a heteroaryl group, each of which may have a substituent(s), and * represents an asymmetric carbon atom, and an optically active (R or S)-α-amino acid ester represented by the formula (III): wherein R has the same meaning as defined above, R 1 represents an alkyl group which may have a substituent(s), and * represents an asymmetric carbon atom, provided that it has an opposite absolute configuration to that of the compound of the formula (II), which comprises selectively reacting water with one of enantiomers of an α-amino acid ester which is a racemic mixture and represented by the formula (I): wherein R and R 1 have the same meanings as defined above, in the presence of a lipase in an organic solvent in a single phase without causing phase separation from a reaction system.