Bis-(cyanoacetamide)alkanes in heterocyclic synthesis: synthesis of bis-heteryl(carboxymido)alkanes and bis-(heteryl)alkanes of thiophene, pyrrole, thiazole and pyrimidinone series

Bis-N-substituted cyanoacetamides 3a and b reacted with active methylene-containing compounds 2a–c and elemental sulfur to give bis-thiophene 4a and b and bis-pyrrole 6a and b derivatives. Compounds 4a and b reacted with ethyl cyanoacetate 2a to afford bis-thienopyrimidine derivatives 5a and b; on the other hand, 6a and b reacted with cyanothioacetamide 2c to give the corresponding bis-thioxopyrrolopyrimidine derivatives 7a and b. Compounds 7a and b reacted with methyl iodide to give the corresponding bis-2-S-methylpyrrolopyrimidine derivatives 8a and b, which could be, in turn, cyclized into the bis-pyrazolopyrrolopyrimidine derivatives 9a and b by refluxing with hydrazine hydrate. On the other hand, 7a and b reacted with ethyl chloroacetate to yield the corresponding bis-thienopyrrolopyrimidine derivatives 10a and b. Finally, compounds 3a and b reacted with phenylisothiocyanate and elemental sulfur to give the corresponding bis-2-thioxoaminothizole derivatives 11a and b.