Water → HCID 57046045, compound

To a solution of (2S, 4R)-2-[2-(hydroxymethyl)-thiazol-4-yl]-4-methanesulfonyloxy-1-(4-nitrobenzyloxycarbonyl) pyrrolidine (2.1 g) in acetonitrile (50 ml) was added chlorosulfonyl isocyanate (0.48 ml) at 0°-5° C. and the mixture was stirred at ambient temperature for 1 hour. Water (3 ml) was added to the solution at the same temperature and the mixture was stirred for 20 hours. After the solvent was removed, the residue was dissolved in ethyl acetate, and washed with water, saturated sodium bicarbonate and brine successively. The dried organic layer was evaporated to give (2S,4R)2- [2-(carbamoyloxymethyl)thiazol-4-yl]-4-methanesulfonyloxy-1-(4-nitrobenzyloxycarbonyl) pyrrolidine (2.2 g).