| Under microwave assistant method, heterocycle fused pyrimide carboxylate derivatives with polysubstituents were synthesized by the one pot multicomponents reaction with2-aminothiazole,2-aminobenzothiazole,2-amino-5-phenyl-[1,3,4]thiadiazol and different aromatic aldehydes and ethyl acetoacetate in the solvent of acetic acid. Six5H-thiazolo[3,2-a]pyrimidine-6-carboxylate derivatives and six5H-[1,3,4]thiadiazolo[3,2-a]pyrimidine-6-carboxylate were obtained. Their structures were characterized and confirmed byIR and NMR spectrum.The three components of2-aminothiazole, benzaldehyde, and ethyl acetoacetate werechoosed as the model reaction by the microwave heating. Different conditions were carriedout such reaction temperature, reaction time, reaction solvents and vary catalysts, and then aoptimal reaction condition was got. Under the optimized set of general conditions the role of2-aminoheterocycle with aromatic aldehydes with various substituent groups were exmined inthis one pot reaction. The results showed that not all aldehydes could be suitable for this onepot reaction and gave the correspondent aim products, which means that general methodwithout the microwave assistant is not popular for the aromatic aldehyde in this one potreaction.While2-aminopyridine reacted with aromatic aldehydes and ethyl acetoacetate in onepot reaction under microwave assistant, the aromatic aldehydes didn’t reacted with the othertwo substrates and the pyridine fuse pyrimide derivatives were not obtained. However, thecorrespondent pyrido[1,2-a]pyrimidin-4-one was observed and characterized by the IR andNMR spectrum. The optimal reaction conditions were obtained under microwave heating.Compared with the general method, the microwave method has shorter reaction time andhigher yields.Slow evaporation of solvent has been got single crystal of ethyl7-methyl-5-phenyl-5H-thiazolo[3,2-a]pyrimidine-6-carboxylate, ethyl7-methyl-5-phenyl-5H-thiadiazolo [3,2-a]pyrimidine-6-carboxylate and ethyl7-methyl-2,5-diphenyl-5H-[1,3,4]thiadiazolo[3,2-a]pyrimidine-6-carboxylate. And the X-ray diffraction analysis, the structures of the compounds were determined. |
