A one pot, efficient and eco-friendly synthesis of 1,3,4-thiadiazolo[3,2-a] pyrimidine scaffold via Aza–Michael addition and intramolecular cyclo-elimination reactions in poly ethylene glycol (PEG)

Potassium carbonate in poly (ethylene glycol-400) has been found to be a highly effective and efficient medium for the straight forward, convenient, one pot and green synthesis of ethyl 2-substituted phenyl-7-oxo-7 H -[1,3,4]- thiadiazolo [3,2-a]- pyrimidine-6-corboxylate and -6-corbonitrile through intramolecular cyclo-elimination of Michael adducts formed between the reaction of 2-amino-5 substituted thiadiazoles with diethyl-2- (ethoxymethylene) malonate and ethyl-2- cyano-3-ethoxyacrylate respectively. The structures of all the new compounds have been elucidated using IR, 1 H and 13 C NMR, mass spectral data and elemental analyses.