Optically active antifungal azoles. I. Synthesis and antifungal activity of (2R,3R)-2-(2,4-difluorophenyl)-3-mercapto-1-(1H-1,2,4-triazol-1-yl)-2-b utanol and its stereoisomers.

(2R,3R)-2-(2,4-Difluorophenyl)-3-mercapto-1-(1H-1,2,4-triazol-1-yl )-2-butano l [(2R,3R)-7] and its stereoisomers [(2S,3R)-, (2S,3S)- and (2R,3S)-7] were prepared from the optically active oxiranes 6 by a newly developed ring-opening reaction and evaluated for antifungal activity. The thiol (2R,3R)-7 showed extremely potent antifungal activity in vitro and in vivo. The optically active oxirane (2R,3S)-6, a useful intermediate for the synthesis of sulfur-containing antifungal azoles 5, was synthesized from methyl (R)-lactate [(R)-8] via eight steps in a stereocontrolled manner. The key step in the synthesis is the Grignard reaction of an amide derivative [(R)-12a] of (R)-lactic acid with 2,4-difluorophenyl-magnesium bromide (13).