Utility of the Enaminonitrile Moiety in the Synthesis of Some Biologically Active Thienopyrimidine Derivatives

Because of its broad spectrum of biological activities, a novel series of thienopyrimidines and fused thienopyrimidines have been synthesized by reacting the enaminonitrile 1 with different reagents. Thus, reaction of 1 with urea, thiourea, formic acid and/or formamide afforded pyrimidine derivatives 2, 3, 4, and 5, respectively. Compound 4 reacted with POCl3/PCl5 giving the chloro-derivative 7 which upon treatment with thiourea, hydrazine, piperidine and/or thiols, produced 4-thio, 4-hydrazino, 4-piperidino- and 4-S-substituted pyrimidine derivatives 8–11, respectively. Treatment of 9 with ethyl chloroformate, sodium nitrite/hydrochloric acid, benzoyl chloride, acetic and/or formic acid, benzaldehyde/piperidine and CS2/pyridine provided the carbazate 13, tetrazole 14, triazoles 15, and 16a, b, Schiff's base 17 and triazole 18, respectively. Some of the new synthesized compounds were screened for antibacterial activity. The structures of these compounds were confirmed by FT-IR, 1H NMR and correct elemental analysis.