Synthesis of 3', 4', 5-Trihydroxy-6, 7, 8-trimethoxyflavone and Its Related Compounds

Abstract

3', 4'-Bis(benzyloxy)-, 4'-benzyloxy-5, 6, 7, 8-tetramethoxy- and 3', 4', 6-tris(benzyloxy)-5, 7, 8-trimethoxyflavones, ([7a], [7b] and, [7c], respectively) were synthesized from the corres-ponding 2-hydroxyacetophenones and the substituted benzoyl chloride via 3 steps. The desired hydroxyflavones [3a-c], which could be inhibitors of lens aldose reductase, were obtained by the hydrogenolysis of benzyloxyflavones [7 a-c] followed by the selective demethylation with anhydrous aluminum chloride in acetonitrile. A natural flavone isolated from Sideritis leucantha Cavanilles was found to be identical with the title compound [3a].