The Keggin heteropoly acid, silicotungstic acid, H4SiW12O40, has been demonstrated to be highly efficient for an expeditious, one-pot synthesis of 1-methyl-2-(hetero) arylbenzimidazoles from N-methyl-1, 2-phenylenediamine and (hetero) aryl aldehydes in ethyl acetate at room temperature. The catalyst works equally well for N-phenyl-1, 2- phenylenediamine.
