Gould-Jacob type of reaction for the synthesis of thieno[3,2-e]pyrimido[1,2-c]pyrimidines (5) has been carried out conventionally by the condensation between 4-aminothieno[2,3-d]pyrimidines (2) and diethyl ethoxymethylenemalonate (3) via acyclic intermediates diethyl N-[5,6-disubstituted thieno[2,3-d]pyrimidin-4-yl]aminomethylenemalonates (4) and the results obtained were compared with single step microwave technique under solvent free conditions for the synthesis of 5.