Pyridine → N-(3,4-Dimethyl-5-isoxazolyl)-2-methylbenzo[b]thiophene-3-sulfonamide

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Reaction Steps

2-Methylbenzo[b]thiophene-3-sulfonyl chloride (1.7 mmoles, 0.41 g) was added to a solution of 3,4-dimethyl-5-aminoisoxazole (0.75 mmoles, 84 mg), 4-dimethylaminopyridine (DMAP; 50 mg) and pyridine (5 ml) at ambient temperature. After 24 h, the reaction mixture was diluted with ethyl acetate (50 ml) and washed with 2% HCl (3×50 ml). The organic phase was dried (MgSO4), filtered and concentrated to collect a brown-orange solid, which was dissolved in a solution of methanol (10 ml) and NaOH (60 mg). The solution was stirred 1 h at ambient temperature, then the methanol was evaporated and the resulting residue was diluted with 2% HCl (50 ml), and extracted with ethyl acetate (75 ml). The organic phase was dried (MgSO4), filtered and concentrated to collect a tan solid. Recrystallization from chloroform and hexanes resulted in 93 mg (38%) of N-(3,4-dimethyl-5-isoxazolyl)-2-methylbenzo[b]thiophene-3-sulfonamide as light yellow crystals, m.p. 174°-176° C.

Provenance & Evidence