Ellagitannin chemistry. The first synthesis of dehydrohexahydroxydiphenoate esters from oxidative coupling of unetherified methyl gallate
Ellagitannin chemistry. The first synthesis of dehydrohexahydroxydiphenoate esters from oxidative coupling of unetherified methyl gallate
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DOI：
10.1021/jo971354k
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发表时间：
1997-12-12
影响因子：
3.6
通讯作者：
Feldman, KS
中科院分区：
文献类型：
--
作者：
Quideau, S;Feldman, KS
邻氯苯酚催化的没食子酸甲酯在无水乙醚中的氧化二聚反应以较高的产率生成了淡黄色的脱氢六羟基二苯酸二甲酯(DHHDP)。这种没食子酸甲酯脱氢二聚体在丙酮中迅速重排，得到两个额外的DHHDP区域异构体的混合物。其中一个物种对应于脱氢纤维素单宁天然产物中常见的脱氢六羟基二苯酰基的异构体。二亚硫酸钠催化还原初始生成的脱氢六羟基二苯酸二甲酯和/或其衍生的区域异构体，可有效地生成六羟基苯二酸二甲酯(HHDP)。N-(羧氧基)-L-半胱氨酸苄酯与脱氢六羟基联苯酸二甲酯(S)在四氢呋喃溶液中加成，生成两个非对映异构体S-S-半胱氨酸二甲酯。
A simple o-chloranil-mediated oxidative dimerization of methyl gallate in anhydrous ether furnishes a dimethyl dehydrohexahydroxydiphenoate (DHHDP) product as a pale yellow precipitate in good yield. This methyl gallate dehydrodimer rapidly rearranges in acetone to give a mixture of two additional DHHDP regioisomers. One of these species corresponds to the isomer of the dehydrohexahydroxydiphenoyl group commonly observed in dehydroellagitannin natural products. Sodium dithionite-mediated reduction of the initially formed dimethyl dehydrohexahydroxydiphenoate and/or its derived regioisomers efficiently furnishes dimethyl hexahydroxydiphenoate (HHDP). Addition of N-(carbobenzyloxy)-L-cysteine benzyl ester to dimethyl dehydrohexahydroxydiphenoate(s) in THF solution produces two diastereomeric S-S-cysteinyl derivatives of dimethyl hexahydroxydiphenoate.