MoO2(ONO) Schiff Base Complex: A Homogeneous Catalyst for the Synthesis of Benzimidazoles Under Various Reaction Conditions

The benzimidazole ring is an important pharmacophore in modern drug discovery. Benzimidazolederivatives exhibit significant activity against several viruses such as HIV, HSV-1 andHCMV [1-2]. Benzimidazoles are very important intermediates in organic reactions. Therefore,the preparation of benzimidazoles has gained considerable attention in recent years. Recently,triaryl benzimidazoles as a new class of antibacterial agents against resistant pathogenicmicroorganisms have been synthesized [3]. In this study, benzimidazoles were preparedunder various reaction conditions by taking a 1:1.1 mol ratio mixture of o-phenylenediamineand the arylaldehydes in the presence of 7 mol % MoO2(ONO) Schiff base complex to givethe desired products in excellent yield (Fig. 1). Efficient preparation of benzimidazoles byreaction of o-phenylenediamine with arylaldehydes in the presence of catalytic amounts ofMoO2(ONO) Schiff base complex as a homogeneous catalyst under reflux conditions is reported.Sonication of this system enhanced the catalytic activity of the catalyst and this wasled to higher product yields and shorter reaction times. Another advantage of the systems, underultrasonic irradiation, is the ability to carry out large-scale reactions.