[NH2:1][C:2]1[O:6][N:5]=[C:4]([CH3:7])[C:3]=1[Br:8].[H-].[Na+].[O:11]1[CH:15]=[CH:14][C:13]([C:16]2[S:20][C:19]([S:21](Cl)(=[O:23])=[O:22])=[CH:18][CH:17]=2)=[N:12]1>C1COCC1>[Br:8][C:3]1[C:4]([CH3:7])=[N:5][O:6][C:2]=1[NH:1][S:21]([C:19]1[S:20][C:16]([C:13]2[CH:14]=[CH:15][O:11][N:12]=2)=[CH:17][CH:18]=1)(=[O:22])=[O:23]A solution of 5-amino-4-bromo-3-methylisoxazole (177 mg, 1.0 mmol) in dry THF (2 mL) was added to a suspension of sodium hydride (60% dispersion in mineral oil, 90 mg, 2.2 mmol) in dry THF (1 mL) at 0-5° C. After stirring at 0-5° C. for 5 min, the reaction was warmed to room temperature for 10 min to complete the reaction. The reaction mixture was re-cooled to 0° C., and 5-(3-isoxazolyl)thiophene-2-sulfonyl chloride (273 mg, 1.1 mmol), which had been dissolved in dry THF (2 mL), was added slowly. Stirring was continued for 1 h; during this period the reaction mixture slowly attained ambient temperature. THF was removed under reduced pressure. The residue was dissolved in water (10 mL), the pH was adjusted to 2-3 by adding concentrated HCl, and was extracted with methylene chloride (3×10 mL). The combined organic layers was dried over anhydrous magnesium sulfate and concentrated under reduced pressure to give N-(4-bromo-3-methyl-5-isoxazolyl)-5-(3-isoxazolyl)thiophene-2-sulfonamide. The pure material was obtained by recrystallization using hexanes/ethyl acetate (160 mg, 41% yield), m.p. 120-123° C.
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