Improving methodology for the preparation of highly substituted imidazoles using nano-MgAl2O4 as catalyst under microwave irradiation

An efficient synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazoles by one-step condensation of  an aldehyde, benzil, ammonium acetate and primary amine in the presence of nanocrystalline magnesium aluminate under microwave irradiation is described. The advantages of this catalyst are including simple work-up, low cost and reusability. Compared with conventional methods, the main advantages of the present procedure are its being a green method, its milder conditions, necessary shorter reaction time, and its higher yields and its selectivity. The structures of products were characterized by 1H NMR, 13C NMR, IR, elemental analyses, MS and UV spectral data. Their melting points were compared with literature report.