Facile Route for the Synthesis of Benzothiazoles and Benzimidazoles in the Presence of Tungstophosphoric Acid Impregnated Zirconium Phosphate under Solvent-Free Conditions

Rapid and efficient condensation reactions of o-phenylenediamine and o-aminothiophenol with various aldehydes were carried out using tungstophosphoric acid impregnated zirconium phosphate in solvent-free conditions to afford the corresponding 2-substituted arylbenzimidazole and aryl-benzothiazole derivatives in good to excellent yields. This procedure constitutes a simple and practical green synthetic method for 2-arylbenzimidazoles and 2-arylbenzothiazoles and their structural analogs. Furthermore, the catalyst can be reused for several times but it will be less active. (C) 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:202-207, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20534