Solvent- and catalyst-free synthesis of bis-adducts of 3-formylchromone as potential antimicrobial agents

A facile and ecofriendly synthesis of new (chromon-3-yl)bis(heteroaryl)methanes 5a-d, from 3-formylchromone 1 and active methylene compounds 2-4 is reported under solvent-free, catalyst-free thermal heating condition in good yields. The synthesized compounds were characterized on the basis of elemental and spectral (IR, H-1 NMR, and mass spectrometry) analysis. All the target compounds were evaluated for their in vitro antimicrobial activity against Streptococcus pyogenes, Methicillin resistant Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Escherichia coli bacterial strains, and fungal cultures of Candida albicans, Aspergillus fumigatus, Trichophyton mentagrophytes, and Penicillium marneffei by disk diffusion assay with slight modifications. The minimum inhibitory concentration was determined for the test compounds as well as for reference standards. Among the tested compounds, 5b has shown the most potent antibacterial as well as antifungal activities.