Microwave-assisted Catalyzed Synthesis and In vitro Bioactivity Evaluation of Benzimidazoles Bearing Phenolic Hydroxyl

An efficient and facile method was introduced for the synthesis of benzimidazoles in this paper. The optimum reaction conditions were determined. A series of benzimidazoles bearing phenolic hydroxyl(2a-2t) were synthesized in moderate to excellent yields starting from differently substituted hydroxyl benzaldehyde and 4-position substituted o-phenylenediamine via nucleophilic addition in the presence of catalyst Na₂S₂O₅ under microwave irradiation condition. Herein, effects of the catalyst, molar ratio of reactants, reaction temperature and solvent were investigated. The optimal reaction condition was determined. The effect of DMF and EtOH solvent on the reaction was compared. The synthesized compounds were characterized by FTIR, HRMS, ¹H NMR and ¹³C NMR spectroscopy. Further, the bacteriostatic activities of the synthesized compounds were evaluated with ciprofloxacin and itraconazole as a positive control, respectively. Compounds 2b, 2n, 2q and 2r exhi-bited some antibacterial activity. The lowest MIC of antibacterial activity of compound 2b was 32 μg/mL. Meanwhile, the luminescence property of compound 2b was studied. The antibacterial activity of compound 2b, along with their good fluorescence performance highlighted the potential of these compounds as lead structures and owned fluorescence trace for further study towards the development of novel drugs and functional mechanisms in living organisms.