Synthesis and characterization of new 3‐acyl‐7‐hydroxy‐6,8‐substituted‐coumarin and 3‐acyl‐7‐benzyloxy‐6,8‐substituted‐coumarin derivatives

Abstract

Abstract magnified image A new series of 3‐acyl‐6,7,8‐substituted coumarin derivatives has been synthesized in high yields (79–99%) and characterized by means of elemental analysis, mass spectrometry, IR, and 1H NMR spectroscopy. We examined with particular attention the presence of an acyl group at position 3 (ethyl ester, carboxylic acid, and acyl chloride), and of a hydroxyl group at position 7 or a functionalized one like benzyloxy or phthalimido. The hydroxyl group has been modified by an etherification in presence of crown ether with substituted benzyl bromide or chloride to evaluate the influence on chemical characteristics and lipophilicity of coumarin nucleus. Halogens (Cl, Br) and methyl group were introduced in position 6 and 8 of the coumarin ring, respectively, in order to study their effect on reaction feasibility. Some of these 3‐acyl derivatives have been recently assayed as MAO inhibitors and as intermediates (i.e. reactive chloride derivative) to design new anti‐Helicobacter pylori agents. J. Heterocyclic Chem., (2010).