Benzimidazoles synthesis in the presence of nano silica chloride as a solid acid catalyst at room temperature

چکیده مقاله

Benzimidazole moieties are classified under several class of drugs,1 based on the possible substitution at different positions of benzimidazole nucleus. Benzimidazole derivatives exhibit significant activity against several viruses such as HIV and also possessing antitumour activity. In addition, benzimidazoles are very important precursors in organic synthesis.2 In the past few decades, a series of significant methods has been subsequently developed to construct benzimidazole. The coupling of o-phenylenediamine with carboxylic acids. These methods are usually performed under strongly acidic conditions, high reaction temperature, and sometimes suffer from low yields. Recently, o-phenylenediamine and aldehydes have been used as starting materials in the preparation of 2-substituted benzimidazoles over various oxidant or catalysts.3 Higher yields, easier work-up, and use of nontoxic solvent are the advantages of this protocol. In this study, we report a simple and efficient method for the synthesis of benzimidazole derivatives using nano silica chloride as a catalyst and atmospheric air as an oxidant at room temperature.