Glyoxylic acid as catalyst: A simple selective synthesis of 1,2-disubstituted benzimidazoles in aqueous media

Glyoxylic acid (5 mol%) performs as a novel highly water-soluble catalyst for the synthesis of 2-aryl-1-arylmethyl-1H-benzimidazoles from a wide range of substituted o-phenylenediamines and various substituted aldehydes in good to excellent isolated yields (85-95%) using water as solvent at ambient temperature. The remarkable advantages offered by this method are easily and inexpensive available catalyst, simple procedure, mild conditions, much faster (20-40 min) reactions and excellent yields of products. (c) 2008 Shivaji N. Thore. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.