Synthesis and derivatization of novel 4-aroylthiophene-and furan-2-sulfonamides

Sulfonation of 3-aroylthiophenes and furans with sulfuric acid in acetic anhydride regioselectively affords the corresponding 2,4-disubstituted heterocycle. Benzylamine derivatives of the parent sulfonamides are obtained either by Mannich reaction of aryl phenols, or via a sequence employing free radical bromination followed by selective ammonolysis. This methodology provides ready access to a wide variety of regioselectively-substituted heterocycles.