Facile Synthesis of 1,2-Disubstituted Benzimidazoles Usingp-Toluenesulfonic Acid through Grinding
Method
摘要:
An efficient synthetic method for the highly selective synthesis of pharmacologically active 1,2-disubstituted benzimidazole derivatives fromo-phenylenediamine and various aromatic aldehydes catalyzed byp-toluenesulfonic acid through grinding under solvent-free condition is described. The reaction requires the catalyst only during the conversion of intermediateN,N '-dibenzylidene-o-phenylenediamine into the desired product. The products were obtained within a short time with good yields by using only a mortar and pestle, which makes the proposed method convenient and cost-effective.
A cost-effective and eco-friendly synthesis of 2-aryl-1-arylmethyl-1H-benzimidazoles has been developed through the condensation of different aldehydes with o-phenylenediamine using alumina-sulfuric acid as a recyclable heterogeneous solid acid catalyst. Morphological properties of the catalyst have been investigated. Effect of different solvents and comparison of alumina-sulfuric acid with different acid catalysts have also been studied. A plausible mechanistic pathway has been proposed on the basis of the isotope labelling experiments where catalytic behaviour of alumina-sulfuric acid has been explained. (C) 2014 Elsevier Ltd. All rights reserved.