Nano SiO2-SO3Hcatalyzed synthesis of 2-arylsubstituted benzimidazoles

Benzimidazole derivatives exhibit significant activity against several viruses such as HIV herpes (HSV-1) [2], RNA [3], influenzaand human cytomegalovirus (HCMV The widespreadinterest in benzimidazole-containing structures has promoted extensive studies for their synthesis. While many strategies are available for benzimidazole synthesis there are twogeneral methods for the synthesis of 2-substituted benzimidazoles One is the coupling of phenylenediamines and carboxylic acids or their derivatives nitriles, imidates, or orthoesters), which often requires strong acidic conditions and sometimes combines with very high temperatures or microwave irradiation The other way involves a two step procedure that includes the oxidative cyclo- dehydrogenation of Schiff bases, which are often generated from the condensation of phenylenediamines and aldehydes Various oxidative and catalytic reagents have been employed for this conversion Some of these methods suffer from one or more disadvantages such as high reaction temperature,prolonged reaction time, and toxic solvents etc. In this paper, nano SiO2- SO3H was used for the synthesis of 2-arylsubstituted benzimidazoles by the condensation of aryl aldehyde with o-phenylenediamine.