Université de Bordeaux, Institut des Sciences Moléculaires (CNRS-UMR 5255), Institut Européen de Chimie et Biologie, 2 rue Robert Escarpit, 33607 Pessac Cedex, France.
Chemistry. 2012 Jul 16;18(29):9063-74. doi: 10.1002/chem.201200517. Epub 2012 Jun 15.
C-glucosidic ellagitannins constitute a subclass of bioactive polyphenolic natural products with strong antioxidant properties, as well as promising antitumoral and antiviral activities that are related to their capacity to interact with both functional and structural proteins. To date, most synthetic efforts toward ellagitannins have concerned glucopyranosic species. The development of a synthetic strategy to access C-glucosidic ellagitannins, whose characteristic structural feature includes an atropoisomeric hexahydroxydiphenoyl (HHDP) or a nonahydroxyterphenoyl (NHTP) unit that is linked to an open-chain glucose core by a C-aryl glucosidic bond, is described herein. The total synthesis of the biarylic HHDP-containing 5-O-desgalloylepipunicacortein A (1 β) was achieved by either using the natural ellagic acid bis-lactone as a precursor of the requested HHDP unit or by implementing an atroposelective intramolecular oxidative biarylic coupling to forge this HHDP unit. Both routes converged in the penultimate step of this synthesis to enable a biomimetic formation of the key C-aryl glucosidic bond in the title compound.
C-糖苷型鞣花单宁是具有强抗氧化性能的生物活性多酚天然产物的一个子类，具有有前途的抗肿瘤和抗病毒活性，这与其与功能和结构蛋白相互作用的能力有关。迄今为止，鞣花单宁的大多数合成工作都涉及吡喃葡萄糖物种。本文描述了一种合成 C-糖苷型鞣花单宁的策略，其特征结构特征包括一个非对映异构的六羟基二苯甲酰基（HHDP）或九羟基三苯甲酰基（NHTP）单元，通过 C-芳基糖苷键与开链葡萄糖核心连接。通过使用天然鞣花酸双内酯作为所需 HHDP 单元的前体，或者通过实施对映选择性的分子内氧化双芳基偶联来构建该 HHDP 单元，实现了含双芳基 HHDP 的 5-O-去没食子酰基表儿茶素 A（1β）的全合成。这两种途径在该合成的倒数第二步中汇聚，使标题化合物中关键的 C-芳基糖苷键能够进行仿生形成。
