To a stirred solution of N-[[4-(5-methyl-3-phenylisoxazol-4-yl)phenyl]sulfonyl]acetamide (Example 39) (0.612 g, 1.72 mmol) in dichloromethane was treated with ethyl bromoacetate (0.20 mL, 0.29 g, 1.72 mmol) and Et3N (0.26 mL, 0.19 g, 1.89 mmol). After 7 days the reaction was still incomplete by TLC. Additional ethyl bromoacetate (0.20 mL, 0.29 g, 1.72 mmol) and Et3N (0.26 mL, 0.19 g, 1.89 mmol) were added and the reaction was stirred for an additional 6 days. The reaction was diluted with dichloromethane and washed with KHSO4 solution, NaHCO3 solution, and brine, dried over MgSO4, filtered and concentrated in vacuo yielding a clear oil. This oil was purified by flash chromatography yielding N-acetyl-N-[[4-(5-methyl-3-phenylisoxazol-4-yl)phenyl]sulfonyl]glycine, ethyl ester (0.243 g, 32%) as a clear colorless oil of suitable purity for use in the next step: 1H NMR (CDCl3 /300 MHz) 8.03 (d, 2H, J=8.7 Hz), 7.47-7.27 (m, 9H), 4.61 (s, 2H), 4.21 (q, 2H, J=7.1 Hz), 2.51 (s, 3H), 2.33 (s, 3H), 1.28 (t, 3H, J=7.1 Hz). FABLRMS m/z 443 (M+H). FABHRMS m/z 442.1201 (M+, C22H22N2O6S Calc'd 442.1199).
