- SYNTHESIS OF 5,8-DIHYDROXY-6,7-DIMETHOXYFLAVONES AND REVISED STRUCTURES FOR SOME NATURAL FLAVONES
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Six 5,8-dihydroxy-6,7-dimethoxyflavones and three 8-hydroxy-5,6,7-trimethoxyflavones were synthesized from 2',5'-dihydroxy-3',4',6'-trimethoxyacetophenone by adapting the selective O-alkylation and dealkylation, and the differentiation between the flavones and their isomeric 6-hydroxyflavones was clarified by 1H NMR and UV spectra.Four natural flavones proposed as 5,8-dihydroxy-6,7-dimethoxyflavones, must have other structures and three are shown to be isomeric 5,7-dihydroxy-6,8-dimethoxyflavones.A flavone, isolated from Helichrysum, is revised to the isomeric 7-hydroxy-5,6,7-trimethoxyflavone,
- Horie, Tokunaru,Kawamura, Yasuhiko,Yamamoto, Hitoshi,Kitou, Takeshi,Yamashita, Kazuyo
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p. 1201 - 1210
(2007/10/02)
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