2,3-Dichloro-5,6-dicyanobenzoquinone (DDQ) mediated oxidationdehydrogenation of 2-aroyl-3,4-dihydro-2H-benzopyrans : Synthesis of 2-aroylbenzopyran-4-ones

Abstract

DDQ mediated an oxidation-dehydrogenation of 2-aroyl-3,4-dihydro-2H- benzopyran prepared from salicylaldehyde to yield 2-aroylbenzopyran-4-one. Stochiometric amount of DDQ, acetic acid and water in refluxing dioxane are the optimal condition for this oxidation-dehydrogenation reaction. A rationally proposed mechanism for this oxidation-dehydrogenation process is based on the isolation of a reaction intermediate viz., 2-benzoyl-8-methoxy-3,4- dihydrobenzopyran-4-one and the identification of the 18O-labled carbonyl group of benzopyran-4-one demonstrating incorporation of labeled H 218O. © ARKAT USA, Inc.