A novel synthesis of 2-arylbenzimidazoles in molecular sieves-MeOH system and their antitubercular activity

Abstract Arylbenzimidazoles have been synthesized as antimycobacterial agents. An efficient synthesis has been developed for 2-arylbenzimidazoles from o -phenylenediamines and aromatic aldehydes in molecular sieves-methanol system. The methodology is straightforward to get 2-arylbenzimidazoles ( 3a – 3z ) in excellent yields with high chemoselectivity over 2-aryl-1-benzylbenzimidazoles ( 4a – 4z ). All these benzimidazole analogues were evaluated against M. tuberculosis in BACTEC radiometric assay. The compounds 4y and 4z exhibited potential antitubercular activity against M. tuberculosis H 37 R V , MIC at 16 µM and 24 µM respectively. The best compound of the series i.e. compound 4y was well tolerated by Swiss-albino mice in acute oral toxicity. Compound 4y possessing a diarylbenzimidazole core, can further be optimized for better activity.