Synthesis, characterization and RHFlab initio simulations of 2-amino-1,3,4-thiadiazole and its annulated ring junction pyrimidine derivatives

Michael addition reaction of the 2-amino-1,3,4-thiadiazole to chalcone as biselectrophile - afforded 5,7-diphenyl-6-[1,3-diphenylpropan-1-on-3-yl][l,3,4]thiadiazolo[3,2-[a]pyrimidine [3] instead of 5,7-diphenyl-5H-[l,3,4]thiadiazolo[3,2-a]pyrimidine [5] via further Michael addition at C[5] in pyrimidine moiety. The structure 3 was established through the aspect of ab initio calculations, elemental analysis and spectral data