This research is aimed at synthesizing pyrimidine heterocycles that contain 1,3,4-thiadiazole ring moiety by microwave-assisted multi-component reactions. For this purpose, synthesizing of [1,3,4] thiadiazolo[3,2-a]pyrimidine-6-carboxylate derivatives was carried out in a single-step reaction using aromatic aldehydes, ethyl acetoacetate, and different derivatives of 1,3,4-thiadiazoles (with molar ratio of 1:2:1 respectively) in the presence of [Et3NH]+[HSO4]- ionic liquid, under solvent-free conditions.Graphical abstractThis research, synthesis of [1,3,4] thiadiazolo[3,2-a]pyrimidine-6-carboxylate derivatives was carried out in a single-step reaction using aromatic aldehydes, ethyl acetoacetate and different derivatives of 1,3,4-thiadiazoles (with molar ratio of 1:2:1, respectively) in the presence of [Et3NH]+[HSO4]- ionic liquid under solvent-free microwave irradiation.