An expeditious synthesis of benzimidazole derivatives catalyzed by Lewis acids

An expeditious and efficient route for the synthesis of benzimidazole derivatives by the reaction of o-phenylenediamines with orthoesters in the presence of Lewis acids was described. ZrCl4, SnCl4 · 5H2O, TiCl4, BF3 · Et2O, ZrOCl2 · 8H2O and HfCl4 exhibited high catalytic activity for this transformation.