Design and Synthesis of New Fused-Heterocycles of [1,3]Thiazolo[4,5-d]pyrimidines via Michael Addition Reaction

– In a simple and efficient convenient method, a series of new fused heterocycles of [1,3]thiazolo[4,5-d]­pyrimidines, 4a–4c were synthesized with good yields. As starting materials, thiosemicarbazide was condensed with 4-N,N-dimethylbenzaldehyde to afford thiosemicarbazone 1 which further cyclized with mercaptoacetic acid to produce 4-thiazolidinone 2. Furthermore, chalcones 3a–3c was prepared through fusion of 4-thiazolidinones with various aldehydes. Finally, the entitled compounds 4a–4c has been obtained via Michael addition reaction of 4-thiazolidinones with thiourea. The chemical structures for all new compounds were deduced from their elemental and spectral analysis.