Patent ID: 7915019

Claim:
A process for preparing an optically active (S or R)-β-amino acid represented by the formula (II): wherein R represents an aryl group which may have a substituent(s), and * represents an asymmetric carbon atom, and an optically active (R or S)-β-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 a reverse absolute configuration to that of the compound of the formula (II), which comprises selectively reacting water and one of enantiomers of a β-amino acid ester represented by the formula (I): wherein R and R 1 have the same meanings as defined above, which is a racemic mixture, in the presence of a lipase in an organic solvent, wherein water is present in an amount equal to, or less than, its solubility in the organic solvent.