Synthesis and antifungal activities of optically active isomers of SM-8668

Synthesis and antifungal activities of optically active isomers of SM-8668 (1) are described. These isomers were prepared in eight steps from m-difluorobenzene. The crucial step was optical resolution of a synthetic intermediate dl-threo-2-(2,4-difluorophenyl)-2-(1-methylthio)ethyloxirane (2). Only (2R,3R)-isomer of 1 showed potent antifungal activities both in vitro and in vivo.