Patent ID: 6982344

Claim:
A method comprising reacting a racemate represented by the formula R 1 —SO 2 —NH—R 2 (II) wherein R 1 and R 2 are the same or different and each is an optionally substituted hydrocarbon group or an optionally substituted heterocyclic group, and only one of R 1 and R 2 contains one asymmetric carbon, or a salt thereof with an optically active compound represented by the formula R a —COOH (III) wherein R a is an optically active and optionally substituted hydrocarbon group or an optically active and optionally substituted heterocyclic group, a salt thereof or a reactive derivative thereof to give a diastereomeric mixture represented by the formula wherein each symbol is as defined above, or a salt thereof, and resolving the diastereomeric mixture or a salt thereof wherein resolution is carried out by solvent extraction, liquid exchange, phase transfer, salting out, crystallization, recrystallization or chromatography, to produce the diastereomer having a steric configuration of the asymmetric carbon for R 1 or R 2 of an R configuration or an S configuration, or a salt thereof.