Hydrochloric Acid → (2S)-2-(2,4-Difluorophenyl)-2-oxiranemethanol

In 14 ml of methanol was dissolved 4.06 g of (S)-2-(2,4-difluorophenyl)-1-isobutyryloxy-3-methane-sulfonyloxy-2-propanol obtained in Example 44. After a temperature of the resulting liquid was kept at 5° C, 14 ml of aqueous solution of 2N sodium hydroxide was added dropwise thereto with cooling at 15° C. or below. After dropping, the resulting liquid was stirred at a temperature of 10° to 15° C. for 2 hours. Thereto 1N hydrochloric acid was added until the liquid was adjusted to pH 7 and methanol was removed under reduced pressure. To the residue was added ethyl acetate to extract. The resulting organic layer was washed with saturated aqueous solution with sodium chloride. The solvent was removed under reduced pressure and the residue was purified by column chromatography on silica gel (eluent n-hexane/ethyl acetate=1/1) to give 2.04 g of oily (S)-2-(2,4-difluorophenyl)-2,3-epoxy-1-propanol. An optical purity thereof was determined in the same manner as in Example 35. (Elution time: 9.24 minutes ((S)-form) and 10.7 minutes ((R)-form)).