l-Proline: an efficient catalyst for the one-pot synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazoles

A simple highly versatile and efficient synthesis of 2,4,5-trisubstituted imidazoles is achieved by three-component cyclocondensation of 1,2-dicarbonyl compound, aldehyde and ammonium acetate using l-proline as a catalyst in methanol at moderate temperature. To explore the utility of this method 1,2,4,5-tetrasubstituted imidazoles were also synthesized. The key advantages of this process are high yields, cost effectiveness of catalyst, easy work-up and purification of products by non-chromatographic methods.