To a solution of 3-Acetoxymethyl-1-(4-methoxy-benzenesulfonyl)-azepane-2-carboxylic acid (107 mg, 0.28 mmoL) in 5.6 mL dichloromethane was added N,N-Diisopropyl ethyamine (0.195 mL, 1.12 mmoL). This solution was cooled to 0° C. and Hydroxyl amine (58.4 mg, 0.84 mmoL) was added followed by PyBroP (155 mg, 0333 mmoL). The reaction was warmed to ambient temperature after 15 minutes and was stopped after 5.5 hours. The residue was diluted with ethyl acetate and washed sequentially with 0.5N HCl, and brine. The organic layer was dried over anhydrous magnesium sulfate and filtered. The solvent was evaporated under reduced pressure and the residue was purified by column chromatography (silica: 0.5% to 1.5% methanol in dichloromethane) to yield Acetic acid 2-hydroxycarbamoyl-1-(4-methoxy-benzene sulfonyl)-azepan-3-ylmethyl ester; MS: (M-H)- =399.
