An efficient, one-pot method for preparation of tri and tetra-substituted imidazoles by condensation of benzil, aldehydes, and ammonium acetate or primary amine in the presence of a catalytic amount of citric acid or poly(4-vinylpyridinium tribromide) (P.V.P.Br3) under solvent-free conditions is reported. The remarkable advantages of this method are the inexpensive green catalyst, mild reaction conditions, simple procedures, and excellent yields of products.
