Studies of the selective O-alkylation and dealkylation of flavonoids. IX. A new method for synthesizing 3, 5-dihydroxy-7, 8-dimethoxyflavones from 3-hydroxy-5, 7, 8- …
2-Hydroxy-3, 4, 6-trimethoxy-ω-(ρ-methoxybenzoyloxy) acetophenone was prepared from 2, 3, 4, 6-tetramethoxyacetophenone via the corresponding ω-bromoacetophenone. Cyclization of the acetophenone with ρ-methoxybenzoic anhydride by application of the Allan-Robinson reaction afforded 3-hydroxy-4', 5, 7, 8-tetramethoxyflavone along with 2-(α- hydroxy-4-methoxybenzylidene)-4, 6, 7-trimethoxycoumaranone. The 5-methoxy group in ...
