In 900 ml of dimethyl sulfoxide was suspended 41.2 g (1.0 mol) of 60% sodium hydride having been washed with hexane, and 226.7 g (1.0 mol) of trimethyloxosulfonium iodide was added to the suspension in divided portions with stirring under cooling with ice. After the evolution of hydrogen gas ceased, stirring was continued at room temperature for an additional 2-hour period. A solution of 193.0 g (0.57 mmol) of 1-(2,4-difluorophenyl)-2-((4-methoxyphenyl)methylthio)-2-methylpropan-1-one in 110 ml of dimethyl sulfoxide was added thereto, followed by stirring for 12 hours. The reaction mixture was poured into ice-water, followed by extraction with ethyl acetate. The organic layer was washed with a saturated sodium chloride aqueous solution and dried. The solvent was removed by distillation under reduced pressure. The residue was subjected to column chromatography and eluted with a mixed solvent of hexane and ethyl acetate (10:1). The solvent was removed by distillation under reduced pressure, and the residue was recrystallized from a mixed solvent of diethyl ether and hexane to obtain 135.8 g (68%) of (±)-2-(2,4-difluorophenyl)-2-(1-((4-methoxyphenyl)methylthio)-1-methylethyl)oxirane as a colorless crystal.
