Synthesis and Study of Antibacterial Effect of 3,4 -Diaryl-6-oxo- 1-phenyl-6,7-dihydro-1H-pyrazolo[3,4-b]pyridine-5-carbonitrile
Objectives: The present study was focused on environment friendly synthesis of cynopyridone compounds. New improved, three component, one-pot, solvent-free method was successfully developed for the synthesis of 3,4 -diaryl-6-oxo-1-phenyl-6,7-dihydro-1H-pyrazolo[3,4-b]pyridine- 5-carbonitrile using ammonium acetate as a green catalyst. Materials and Methods: Use of multicomponent, one pot synthetic approach in organic synthesis is becoming popular due their simple procedure and high yield of the product. This approach requires less time and minimum raw materials as compared to stepwise synthetic methods. Aromatic aldehyde, ethyl cyanoacetate and 3-aryl-1-phenyl-1H-pyrazol-5-amine (or 1,3-diphenyl-1H-pyrazol-5-amine) in presence of ammonium acetate at elevated temperature produce title compound in good yield. Structure determination of newly synthesized compounds were done by using IR and NMR spectroscopy. Furthermore, compounds were screened for their in vitro antibacterial activity towards gram-positive (B. subtilis, S. aureus) and gram-negative (K. pneumoniae, E. coli) bacteria by using the disc diffusion method. Results: The results of the antibacterial study showed that many substituted cynopyridone compounds have good to moderate antibacterial activity. Compounds having two halogen substituents showed better activity as compare to other compounds. Conclusion: This new improved method offers many advantages like easy workup, mild reaction conditions, good quality product and improvement in product yield as compared to earlier methods. By using this multi-component approach, we can significantly reduce the production cost and environmental pollution.