An Efficient Microwave-assisted Synthesis of Some New Pyridyl Pyrazoline Substituted Coumarins and Its Biological Evaluation

Background: Coumarin belongs to a group known as benzopyrones which consist of a benzene ring joined to a pyrone nucleus which possesses varied biological activities. The current work described the Microwave-assisted synthesis of various pyridyl pyrazoline substituted coumarins. These newly formed coumarin derivatives are characterized by spectra analysis and screened for their in vitro antimicrobial screening against bacterial and fungal pathogens by Broth dilution method. Methods: In the synthetic method, the target compounds were synthesized by reacting different coumarin chalcones with hydrazine hydrate in acetic acid or propionic acid and phenylhydrazine derivatives in acetic acid respectively with the help of microwave irradiation method. Results: The structures of all the synthesized compounds were established by IR, 1H-NMR, 13C-APT and some representative mass spectral data. The target compounds were also screened for their in vitro antimicrobial screening against a representative panel of bacteria (Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Salmonella typhi) and fungi (Aspergillus niger and Candida albicans). Conclusion: In conclusion, the final products were obtained by utilizing Microwave Irradiation (MWI) technique in excellent yields with a short reaction time. Among all the synthesized compounds, 3a, 3d, 7a and 7c were found to have significant activity against bacterial and fungal strains.