Behavior of 2-cyano-3-(dimethylamino)-N-(4-phenylthiazol-2-yl)acrylamide towards some nitrogen nucleophiles

The versatile, hitherto unreported 2-cyano-3-(dimethylamino)-N-(4-phenylthiazol-2-yl)acrylamide 2 was synthesized and allowed to react with hydroxylamine, hydrazine and guanidine to afford regioselectively the isoxazole 4, pyrazole 6 and pyrimidine 8 derivatives, respectively. The reaction of 2 with thiourea and / or ethyl glycinate in a basic medium afforded the regioisomeric pyrimidinethione 9 and 3,5-dioxo-1,4-diazepine-6-carbonitrile 14. Compound 2 reacts also with 2-amino-4-phenylthiazole, 2-amino-4-methylpyridine, 2-aminotetrazole, 2-aminobenzothiazole and 2-aminobenzimidazole to give the corresponding bridgehead nitrogen heterocycles namely thiazolo[3,2-a]pyrimidine 18, tetrazolo[1,5-a]pyrimidine 19, pyrimido [2,1-b]benzothiazole 21, and pyrido[1,2-a]benzimidazole 23. The mechanistic aspects for the formation of the newly synthesized compounds is discussed.