Asymmetric synthesis of the sulfoxide metabolite of ON-579 by the kagan protocol

A synthesis of both enantiomers of bio-active metabolite of ON-579; 4-[2-(4-chlorophenyl-sulfonylamino)-ethylsulfinyl]-2,6-difluorophnoxyacetic acid was accomplished by the asymmetric oxidation of ON-579 methyl ester followed by hydrolysis. Difference in TXA2 receptor antagonizing activity was noted for the enantiomers in an U46619-induced rabbit platelet aggregation inhibitory activity.