Synthesis and Biological Studies of 4‐Methyl-7‐Ethylcoumarin Derivatives Containing Azo Group

Abstract

New 4-methyl-7-ethylcoumarin derivatives bearing the azo group were synthesized through series ‎of sequential reactions and tested for their biological activity. Starting from 4‎-methyl-7-ethylcoumarin ‎ prepared from a reaction of m-ethyl phenol and ethyl acetoacetate by pechmann ‎condensation reaction, nitration of 4 -methyl-7-ethyl coumarin using nitric acid was carried out in the ‎presence of sulfuric acid to produce one isomer from 4-methyl-7-ethyl-8-nitrocoumarin under the ‎cold condition at (2-5Cº). Then reducing nitro group used iron metal in an acidic medium to form ‎corresponding amino coumarin, which was converted to azo dyes by reacting its diazonium salt ‎with different phenol derivatives. Mass, FT-IR, 1H-NMR, 13C-NMR, UV spectra, and ‎TLC chromatography signposted the preparation compounds. The synthetic ‎compounds' biological activities were evaluated against Gram-positive bacteria (Staphylococcus ‎aureus) and Gram-negative bacteria (Escherichia coli) at 1×10-3M. It was found that compounds 4 ‎and 6 have a broad spectrum against different types of bacteria, Staphylococcus aureus, and ‎Escherichia coli, compared to the standard drug vancomycin. In contrast, all compounds showed ‎moderate activity against fungi compared with nystatin. The newly synthesized compounds also ‎showed powerful antioxidants compared with ascorbic acid as a standard, especially compound 7 ‎, which showed high effectiveness as an antioxidant compared to the same reference Ascorbic Acid.