Fusions of pyrido[4′,3′:4,5]thieno[2,3-d]pyrimidines with N-heterocyclic moieties

Versatile 2-thioxopyrimidine-type building blocks ethyl 3-(2-ethoxy-2-oxoethyl)-4-oxo-2-thioxo-1,2,3,4,5,6,7,8-octahydropyrido[4',3':4,5]thieno[2,3-d]pyrimidine-7-carboxylate (4) and ethyl 4-oxo-2-thioxo-1,2,3,4,5,6,7,8-octahydropyrido[4',3':4,5]thieno[2,3-d]pyrimidine-7-carboxylate (8) were synthesized from diethyl 2-amino-4,5,6,7-tetrahydrothieno[2,3-c]pyridine-3,6-dicarboxylate (1). Derivatives of linear and angular heterocyclic systems having the imidazole and 1,2,4-triazole ring were obtained from the key intermediates 4 and 8, respectively.