Patent ID: 9682913
Date: 2017-06-20
CPC Classifications: A61K,A61P,C07B,C07C,C07D

Claim:
1. A method for improving optical purity of a hydroxycarboxylic acid of the following formula (1a) or (1b) or a derivative thereof, the method comprising the steps of: reacting the hydroxycarboxylic acid of the following formula (1a) or (1b): wherein R 1 represents a C 1-8 alkyl group, with at least one optically inactive base selected from the group consisting of an alkali metal alkoxide and a secondary amine in the presence of a solvent and, subsequently, performing recrystallization, to thereby form a hydroxycarboxylic acid salt of the following formula (IIIa) or (IIIb): wherein R 1 has the same meaning as defined above, and R 2 represents an alkali metal or a secondary amine.