Studies of the Selective O-Alkylation and Dealkylation of Flavonoids. XII. : A New, Convenient Method for Synthesizing 3, 5-Dihydroxy-6, 7-dimethoxyflavones from 3, 5, 6, 7-Tetramethoxyflavones

Tokunaru HORIE; Yasuhiko KAWAMURA; Masao TSUKAYAMA; Shiro YOSHIZAKI

doi:10.1248/cpb.37.1216

Tokunaru HORIE, Yasuhiko KAWAMURA, Masao TSUKAYAMA, Shiro YOSHIZAKI

Author information

Keywords: Allan-Robinson reaction, selective demethylation, 3, 5, 6, 7-tetramethoxyflavone, 5-hydroxy-3, 6, 7-trimethoxyflavone, 6-hydroxy-3, 5, 7-trimethoxyflavone, 5-tosyloxyflavone, 5, 6-dihydroxy-3, 7-dimethoxyflavone, 3, 5-dihydroxy-6, 7-dimethoxyflavone, 3, 5-diacetoxy-6, 7-dimethoxyflavone

JOURNAL FREE ACCESS

1989 Volume 37 Issue 5 Pages 1216-1220

DOI https://doi.org/10.1248/cpb.37.1216

Details

Abstract

The 5-methoxy group on 3, 5, 6, 7-tetramethoxyflavones and the 3-methoxy group on 3, 6, 7-trimethoxy-5-tosyloxyflavones were selectively cleaved with anhydrous aluminum bromide in acetonitrile under controlled conditions without the cleavage of benzyloxy groups on the B ring. By the application of these reactions, seven 3, 5-dihydroxy-6, 7-dimethoxyflavones were easily synthesized from the corresponding 3, 5, 6, 7-tetramethoxyflavones which were synthesized from 3, 6-dihydroxy-2, 4-ω-trimethoxyacetophenone by means of the Allan-Robinson reaction followed by methylation.

Corresponding author

Register with J-STAGE for free!