A convenient ‘one-pot’ synthesis and in vitro microbiological evaluation of novel 2,7-diaryl-[1,4]-diazepan-5-ones

Abstract

A convenient method for the ‘one-pot’ synthesis of novel target molecule 2,7-diaryl-[1,4]-diazepan-5-ones from the respective 2,6-diaryl-piperidin-4-ones was catalyzed by NaHSO₄.Al₂O₃ heterogeneous catalyst in dry media under microwave irradiation in solvent-free conditions. Moreover, the catalyst could be recovered and re-used up to 4 times after washing with ethyl acetate. They were evaluated for potential antibacterial activity against Staphylococcus aureus, β-Haemolytic streptococcus, Vibreo cholerae, Salmonella typhii, Escherichia coli, Klebsiella pneumonia, Pseudomonas and antifungal activity against Aspergillus flavus, Aspergillus fumigatus, Mucor, Candida albicans and Rhizopus. Structure-Activity Relationship (SAR) led to the conclusion that, of all the compounds 25–32 tested, compound 30 exerted strong in vitro antibacterial activity against S. aureus, S. typhii, and Pseudomonas and all the compounds 25–32 were less active against E. coli, whereas all the compounds 25–32 displayed potent in vitro antifungal activity against all the fungal strains used, except compound 30, which was more effectual against Mucor.

Keywords::

• 2,7-diaryl-[1,4]-diazepan-5-ones
• NaHSO₄.Al₂O₃ Heterogeneous Catalyst
• Green Chemistry
• Antibacterial activity
• Antifungal activity

Acknowledgements

The Authors are thankful to Professor K. Pandiarajan, Head, Department of Chemistry, Annamalai University for providing the necessary facilities. P. Sureshkumar, V. Kanagarajan and J. Thanusu are highly thankful to the Annamalai University authorities for providing financial support in the form of Research Fellowship.