Junchao Yu, J. Cal, Yi-Sheng Gao
Aug 27, 2010
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Journal
Chinese Journal of Chemistry
Abstract
8-Hyaroxysubspinosin was elucidated as 2,8-dihydroxy-3-ethoxymethyl-1-methoxyanthraquinone (2) in the literature. Here, the structure revision and synthesis of 8-hydroxysubspinosin were presented. It should be revised to 3,5-dihydroxy-2-ethoxymethyl-1-methoxyanthraquinone (5), i.e. 5-hydroxydamnacanthol-ω-ethyl ether by comparison with the synthetic sample. 5 was synthesized by alkylation of 3-bromo-7-methoxyphthalide (10) with 2,6-dimethoxytoluene in the presence of stannic chloride, followed by reductive cleavage, cyclization, oxidation, demethylation, selective acetylation, methylation, bromination and condensation with sodium ethoxide. The isomer 1,3-dihydroxy-2-ethoxymethyl-5-methoxyanthraquinone (5b) was also obtained.