Some novel 3,5-diaminothiophenes (5, 7 and 11) and 2,3-dihydrothiazoles (10 and 13) were synthesized from the reaction of malononitrile with 4-isothiocyanatosulfonamide (2) in the presence of potassium hydroxide followed by in situ hetero-cyclization of the resulting adduct (3) with various α-halogenated reagents.