Synthesis and antimicrobial activity of novel coumarin derivatives from 4-methylumbelliferone

Abstract

Considering the potential interest of heterocyclic compounds, the aim of the present study is to synthesize new coumarin derivatives, to provide their full chemical characterization and to evaluate their antimicrobial activities. The reaction of ethyl 2-(4-methyl-2-oxo-2H-chromen-7-yloxy) acetate 2 with sodium hydroxide afforded the corresponding 2-(2-oxo-4-methyl-2H-chromen-7-yloxy) acetic acid 3 which was esterified using a series of alcohols in the presence of iodine to yield a new series of coumarin esters 4a–j. On the other hand, treatment of the key intermediate 2 with an aqueous solution of hydrazine in ethanol at reflux gave the corresponding hydrazide 5 which further converted into coumarin derivatives 6a–f and 7a–c by condensation with a series of aromatic aldehydes and cyclic anhydrides, respectively. The synthesized compounds were completely characterized by 1H NMR, 13C NMR, IR and HRMS. The antibacterial and antifungal activities of the new synthesized compounds were evaluated using the disc diffusion method and seemed to be significant.