Methylation of dihydroquercetin acetates:: Synthesis of 5-O-methyldihydroquercetin
Methylation of dihydroquercetin acetates:: Synthesis of 5-O-methyldihydroquercetin
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DOI：
10.1021/np034005w
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发表时间：
2003-12-01
影响因子：
5.1
通讯作者：
Slade, PW
中科院分区：
文献类型：
--
作者：
Kiehlmann, E;Slade, PW
二氢栎素(1，DHQ)与重氮甲烷甲基化的主要产物为7-O-甲基dhq(9)、7，3‘-二-0-甲基dhq(10)、7，4’-二O-甲基dhq(11)和7，3‘，4’-tri-O-甲基dhq(2)。与DHQ 3，7，3‘，4’-四乙酸酯(6)，DHQ 3，5，3‘，4’-四乙酸酯(5)，DHQ 3，3‘，4’-三乙酸酯(7)，DHQ 7，3‘，4’-三乙酸酯(8)和DHQ 3-乙酸酯(4)相同的反应主要得到5-O-甲基dhq 3，7，3‘，4’-四乙酸酯(15)，7-O-甲基dhq 3，5，3‘，4’-四乙酸酯(13)，7-O-甲基dhq 3，3‘，4’-三乙酸酯(14)，5-O-甲基dhq 7，3‘，4’-三乙酸酯(25)，和7-O-甲基dhq-3-乙酸酯(12)。8的甲基化伴随着分子间的乙酰基从酚氧迁移到杂环的羟基。5-O-甲基dhq(28)可通过25脱乙酰基获得。5，7-二-O-甲基dhq(29)，4个已知的甲醚，13个新的和3个已知的DHQ的甲醚乙酸酯，以及6个具有2，3-顺式立体化学的新异构体。
The major products of methylation of dihydroquercetin (1, dhq) with diazomethane have been identified as 7-O-methyldhq (9), 7,3'-di-0-methyldhq (10), 7,4'-di-O-methyldhq (11), and 7,3',4'-tri-O-methyldhq (2). With dhq 3,7,3',4'-tetraacetate (6), dhq 3,5,3',4'-tetraacetate (5), dhq 3,3',4'-triacetate (7), dhq 7,3',4'triacetate (8), and dhq 3-acetate (4) the same reaction affords mainly 5-O-methyldhq 3,7,3',4'-tetraacetate (15), 7-O-methyldhq 3,5,3',4'-tetraacetate (13), 7-O-methyldhq 3,3',4'-triacetate (14), 5-O-methyldhq 7,3',4'triacetate (25), and 7-O-methyldhq 3-acetate (12), respectively. The methylation of 8 is accompanied by intermolecular acetyl migration from phenolic oxygen to the hydroxy group of the heterocyclic ring. 5-O-Methyldhq (28) is accessible by deacetylation of 25. 5,7-Di-O-methyldhq (29), four known methyl ethers, 13 new and three known methyl ether acetates of dhq, and six new isomers with 2,3-cis stereochemistry were spectroscopically identified.