Studies with Heterocyclic β-Enaminoniriles: A Simple Route for the Synthesis of Polyfunctionally Substituted Thiophene, lmidazo[1,2:1′,6′]pyrimido[5,4-b]thiopheneand Thieno[3,2-d]pyrimidine Derivatives

摘要

Reaction of 3,5-diaminothiophene-2-carbonitrile derivatives 3a-c with ethoxycarbonylmethyl isothio-cyanate and/or N-[bis(methylthio)methylene]glycine ethyl ester led to formation of 7-substituted-8-amino-5-thioxo-6H-imidazo[1,2:1′,6′]pyrimido[5,4-b]thiophene-2(3H)-one derivatives 6a-c and 7-substituted-8-amino-5-(methylthio)imidazo[1,2:1′,6′]pyrimido[5,4-b]thiophene-2(3H)-one 7a-c, respectively. Also, the synthetic potential of the β-enaminonitrile moiety in 3a-c has been explored; it proved to be a promising candiate for the synthesis of 1,6-disubstituted-2,4-diamino-7,8-dihydro-8-oxopyrrolo[1,2-a]thieno[2,3-e]py-rimidine derivatives 10a-f and pyrido[2′,3′:6,5]pyrimido[3,4-a]benzimidazole derivatives 12a,b.