A Convenient One-Pot Synthesis of Novel Benzimidazole-Thiazinone Derivatives and Their Antimicrobial Activity.

The increasing prevalence of antimicrobial resistant highlights the urgent need for the new therapeutic agents. This study aimed to design and synthesize fused tricyclic benzimidazole-thiazinone derivatives (-) through a convenient method and evaluate their antimicrobial activity against various microorganisms. A series of fused tricyclic benzimidazole-thiazinone derivatives was rationally designed and synthesized in one pot by the reaction between trans substituted acrylic acids and 1-benzo[d]imidazole-2-thiol using coupling reagent TBTU (2-(1-benzotriazol-1-yl)-1,1,3,3-tetramethyluronium tetrafluoroborate). The structure of these compounds was confirmed through various spectroscopic techniques like IR, H and C NMR, the DEPT and 2D-HMQC NMR techniques were also performed to confirm the relation of both carbon and proton. Further, the compounds were in vitro evaluated for their effectiveness against the species and a panel of standard bacterial isolates. The synthesized compounds showed moderate antimicrobial activity. Among all of the compounds, exhibited potent inhibition against and at 256 and 512 μg/mL concentrations, respectively. Additional research indicated that compound demonstrated a synergistic effect after combining with the standard antibacterial drug ciprofloxacin. These results suggest that is the best-synthesized antibacterial agent particularly in combination therapies. These findings highlight its promise for further development as a novel antibacterial agent.