To a stirred solution of phenyl 5-(1-hydroxy-2-methylpropan-2-yl)isoxazol-3-ylcarbamate (prepared as described in Example 131A steps 1 through 4) (250 mg, 0.91 mmol) and pyridine (0.15 mL, 1.81 mmol) in dichloromethane (5 mL) at 0° C., was added dropwise, 4-nitrophenylsulfonyl chloride (245 mg, 1.08 mmol) in dichloromethane (3 mL). The reaction mixture was warmed to 35° C. and stirred for a further 15 h. Concentration under reduced pressure gave the crude product which was purified via silica gel column chromatography (eluting with 20% ethyl acetate in petroleum ether) to afford 2-methyl-2-(3-(phenoxycarbonylamino)isoxazol-5-yl)propyl 4-nitrobenzenesulfonate (250 mg, 60%) as a yellow solid. 1H NMR (400 MHz, CDCl3) δ 8.36-8.39 (m, 2H), 8.01-8.03 (m, 2H), 7.88 (m, 1H), 7.43-7.45 (m, 2H), 7.21-7.31 (m, 3H), 6.54 (s, 1H), 4.19 (s, 2H), 1.38 (s, 6H).
