Ultrasound Assisted Synthesis, Characterization and Antimicrobial Evaluation of Novel Oxazolidinone- Biphenyl Chalcone Hybrid Derivatives

Abstract:

Objective: The main objective of our present study, is to potentiate the antibacterial activity of biphenyl chalcones and oxazolidinones, thus in order to achieve the potent antibacterial agents, we coupled both derivatives by using green chemistry approach for Buchwald’s protocol under ultrasound irradiation. Methodology: Ultrasonication technique was used to couple a series of 24 novel bromo-biphenyl-chalcone derivatives and 5-chloromethyl-oxazolidinone in the presence of copper iodide (CuI) (10 mol %) for the amidation of chalcones and (±)-trans-1,2-diaminocyclohexane was used to solubilize CuI and potassium carbonate (K₂CO₃) as base, which provided the products in good yields after short reaction times under mild conditions. Results and Discussion: Herewith we report the synthesis of 24 novel oxazolidinone-biphenyl chalcone hybrid derivatives (7a-7x). All the synthesized compounds were characterized by spectral data and evaluated for in vitro antibacterial and antifungal activities. Antibacterial and antifungal activities were tested using the serial dilution method. From the screening studies it was observed that compounds 7c to 7g have shown significant antibacterial activities against the both the strains of gram-positive and gram-negative bacteria at 3.125 μg/ml when compared to the standard drugs ciprofloxacin and linezolid and were as other compounds showed moderate to weak activities. In case of antifungal studies the compounds 7e-7g showed moderate activities at 12.5 μg/ml compared to standard fluconazole and whereas other compounds showed weak activities. Conclusion: We have developed an experimentally simple, efficient, short time and high yielding CuI-mediated N-arylation of oxazolidinones under ultrasound irradiation with a simple set up at room temperature. This approach would be a worthwhile in the development of green chemistry protocols. Compounds 7c to 7g have shown significant antibacterial activities against the both the strains of gram-positive and gram-negative bacteria.

Key words: Buchwald’s Protocol, Ultrasound (US) irradiation, Lithium hydroxide monohydrate (LiOH.H₂O), Aryl aldehydes, Biphenyl chalcones, 5-chloromethyloxazolidinone.