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- …

T HORIE, M TSUKAYAMA, Y KAWAMURA…

Index: Horie, Tokunaru; Tsukayama, Masao; Kawamura, Yasuhiko; Yamamoto, Shigeo Chemical & Pharmaceutical Bulletin, 1987 , vol. 35, # 11 p. 4465 - 4472

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Citation Number: 18

Abstract

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 ...