2-Amino benzothiazole (1) and 2-amino-6-methyl benzothiazole (4) in N, N'-dimethyl formamide (DMF) and anhydrous potassium carbonate reacted with bis(methylthio) methylene malononitrile (2) to afford 3-cyano-4-imino-2-methylthio-4H-pyrimido [2,1-b] [1,3] benzothiazole (3) and 3-cyano-4-imino-2-methylthio-8-methyl-4H-pyrimido [2,1-b] [1,3] benzothiazole (5), respectively. The latter were further reacted with selected N-, O- and C- nucleophiles such as aryl and hetaryl amines, substituted phenols and compounds with an active methylene group.