One-pot synthesis of coumarin derivatives via microwave assisted Pechmann reaction and biological activity of substituted coumarin derivatives

Abstract

Pechmann reaction is mainly used for the synthesis of substituted coumarins as it can be executed with straight forward primary resources and gives coumarin derivatives with excellent yields. In the present work coumarin derivatives have been synthesized by condensation of β-ketoesters and substituted phenols under microwave irradiation in solvent free condition in which oxalic acid is used as catalyst. Oxalic acid is found to be a potential environment friendly catalyst for synthesis of coumarins. The new method of synthesis described here offers a number of advantages of being convenient, safe, gentle, shorter reaction time, high yield, and cleanness as compared to the conventional methods. The synthesized compounds have been systematically characterized by IR and MS analyses. All products are examined for antimicrobial activity against the Gram positive (Staphylococcus aureus and Bacillus subtilis) and Gram negative (Escherichia coli and Salmonella typhi) bacteria and antifungal activity against two fungal species (Aspergillus sp. and Fusarium graminearum). All the compounds inhibited the growth of bacteria as well as fungi.