Methanesulfonyl chloride (224.61 μL, 2.90 mmol) is added to di-tert-butyl (1S,2S,4S,5R,6R)-2-[(tert-butoxycarbonyl)amino]-4-hydroxy-bicyclo[3.1.0]hexane-2,6-dicarboxylate (400 mg, 967 μmoles) and triethylamine (472 μL, 3.39 mmol) in tetrahydrofuran (4.84 mL) at 0° C. and stirred. Cooling bath is removed and the reaction is allowed to warm to room temperature and stirred overnight. Dilute with water and saturated aqueous sodium bicarbonate then extract with ethyl acetate. The combined organics are washed with brine, dried over sodium sulfate, filtered, and concentrated to under reduced pressure to give the title compound (600 mg, 1.22 mmol, 100%).
