Synthetic Studies of the Flavone Derivatives. V. The Use of DDQ in the Dehydrogenation of Flavanones. (I).

Abstract

A novel procedure is described for the expedient preparation of flavone. Application of 2, 3-dichloro-5, 6-dicyano-1, 4-benzoquinone (DDQ) in boiling dioxane as dehydrogenating agent to the several flavanones, e.g. 5, 6, 7-trimethoxy-, 4', 5, 7-trimethoxy-, 4', 5, 6, 7-tetramethoxy-, 4', 5, 6, 7, 8-pentamethoxy-, 4'-benzyloxy-5, 6, 7-trimethoxy-, 3', 4', 5, 6, 7-pentamethoxy-, 4'-benzyloxy-3', 5, 6, 7-tetramethoxy- and 3', 4'-dibenzyloxy-5, 6, 7-trimethoxyflavanone, furnishes a convenient and appropriate method for the preparation of the corresponding flavones, in excellent yields or without any contamination of undesired products.