Synthesis of New Fused Thieno[3,2-d]pyrimidine Derivatives Based on 4-(Furan-2-yl)-7,7-dimethyl-2-sulfanyl-7,8-dihydro-5H-pyrano[4,3-b]pyridine-3-carbonitrile

Methods of synthesis of new fused thieno[3,2-e]pyridines and thieno[3,2-d]pyrimidines have been developed. 4-(Furan-2-yl)-7,7-dimethyl-2-sulfanyl-7,8-dihydro-5H-pyrano[4,3-b]pyridine-3-carbonitrile has been found to react with 2-chloroacetamides in two directions, depending on the temperature. The reaction at elevated temperature (60–65°C) involved alkylation followed by intramolecular cyclization with the formation of pyrano[4,3-b]thieno[3,2-e]pyridine derivatives, whereas at room temperature, the corresponding 2-sulfanyl­acetamides were obtained. The condensation of pyrano[4,3-b]thieno[3,2-e]pyridine-2-carboxamides with triethyl orthoformate afforded new fused tetracyclic thieno[3,2-d]pyrimidine derivatives.