A methylene chloride solution (20 ml) of (4S,5R)-tert-butyl 4-(fluoromethyl)-5-(4-(3-(hydroxymethyl)isoxazol-5-yl)phenyl)-2,2-dimethyloxazolidine-3-carboxylate (876 mg, 2.16 mmol) is cooled to 0° C. and methanesulfonyl chloride (250 mg, 2.16 mmol) is added followed by diisopropylethylamine (278 mg, 2.16 mmol). The reaction is stirred for one hour at 0° C. The reaction is diluted with methylene chloride (20 ml) and washed with water (2×10 ml). The organic phase is dried over sodium sulfate and concentrated to give the title compound (987 mg): m/z (Cl) 485 ([M+H]+.
