C(Cl)(=O)C(Cl)=O.[Br:7][C:8]1[N:13]=[CH:12][C:11]([CH2:14][CH2:15][C:16]([CH3:24])([S:20]([CH3:23])(=[O:22])=[O:21])[C:17](O)=[O:18])=[CH:10][CH:9]=1.C[Si](C)(C)[O:27][NH2:28].CO>ClCCl.O.CN(C=O)C>[Br:7][C:8]1[N:13]=[CH:12][C:11]([CH2:14][CH2:15][C:16]([CH3:24])([S:20]([CH3:23])(=[O:22])=[O:21])[C:17]([NH:28][OH:27])=[O:18])=[CH:10][CH:9]=1DMF (1.6 uL, 0.02 mmol, 0.01 equiv) was added to a solution of oxalyl chloride (1.0 mL, 2.07 mmol, 1.0 equiv) and 4-(6-bromopyridin-3-yl)-2-methyl-2-(methylsulfonyl)butanoic acid (695 mg, 2.07 mmol, 1.0 equiv) in dichloromethane (20 mL) at room temperature. After 10 min (gas evolution subsided), O-(trimethylsilyl)hydroxylamine (843 uL, 6.2 mmol, 3.0 equiv) was added and the reaction was allowed to stir overnight. Methanol (8.8 mL) was added, and the reaction was allowed stir for an additional hour. The reaction was diluted with water (80 mL), and the resulting mixture was extracted with ethyl acetate (2×65 mL). The combined organic layers were washed with brine (40 mL), dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure to provide the title compound as a white powder (666 mg, 92%). MS (LCMS) m/z 353.0 (M+1).
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