Synthesis and in vitro Study of Novel Methylenebis(phenyl‐ 1,5‐benzothiazepine)s and Methylenebis(benzofuryl‐1,5‐benzothiazepine)s as Antimicrobial Agents

AbstractA series of methylenebis(phenyl‐1,5‐benzothiazepine)s 4 and methylenebis(benzofuryl‐1,5‐benzothiazepine)s 5 were prepared by the reaction of methylene‐bis‐chalcones 3 with 2‐aminothiophenol for 4 and followed by the condensation with chloroacetone for 5. The structures of the synthesized compounds have been confirmed by their IR, 1H NMR, 13C NMR, MS and elemental analyses. All the synthesized compounds were tested for their antimicrobial activity against Gram‐positive, Gram‐negative bacteria and fungi. To elucidate the essential structural requirements for the antimicrobial activity, the preliminary structure‐activity relationship has been described. Among the compounds tested, the dimeric compounds 4f, 4g, 5f and 5g were found to be most active against Bacillus subtilis, Bacillus sphaericus, Staphylococcus aureus, Klebsiella aerogenes and Chromobacterium violaceum. Similarly these dimeric compounds showed potent antifungal activity against Candida albicans, Aspergillus fumigatus, Trichophyton rubrum, and Trichophyton mentagrophytes. It is interesting to note that the dimeric compounds with substituents of heterocyclic ring at the 4th position of benzothiazepine system displayed notable antibacterial activity equal to that of streptomycin and penicillin. Further, the activity of all the dimeric compounds was compared with that of their monomeric compounds, and it is interesting to note that almost all the dimeric compounds showed enhanced activity than their monomeric compounds.