5-Amino-3-methylisoxazole → N-(3-methyl-5-isoxazolyl)-5-bromothiophene-2-sulfonamide

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N-(3-methyl-5-isoxazolyl)-5-bromothiophene-2-sulfonamide was prepared in the same manner as described in Example 14 from 5-bromothiophene-2-sulfonyl chloride and 5-amino-3-methyl isoxazole. Purification was achieved by extraction of the crude sulfonamide into aqueous 2N NaOH, washing of the aqueous layer with ethyl acetate and acidification, using concentrated HCl, to pH ~2. Re-extraction into ethyl acetate was followed by washing of the organic material with water, brine and drying over magnesium sulfate. After evaporation of solvents, a brownish solid remained which was sufficiently pure to use in the next step.

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