Regioselective synthesis and theoretical studies of novel bis(tetrahydro[1,2,4]triazolo[5,1-b]quinazolin-8(4H)-ones) catalyzed by ZnO nanoparticles

摘要

A novel series of bis(tetrahydro[1,2,4]triazolo[5,1-b]quinazolin-8(4H)-ones) were prepared in a regioselective manner via a three component reaction of bis-aldehydes with 5-amino-1,2,4-triazole and dimedone under microwave irradiation as well as under conventional heating. The reactions were carried out in the absence as well as in the presence of ZnO nanoparticles as a heterogeneous catalyst. Best results were achieved when these reactions were carried out under MW heating. The presence of ZnO nanoparticles was found to improve the yields of the reactions but did not change the regioselectivity the products. The reaction mechanism and the unambiguous structural elucidation of the expected regioisomers were studied using DFT calculations as well as 2D-HMBC spectroscopy.