The first total synthesis of (±)-eleutherol and eleuthoside A, the natural cytotoxic substances extracted from medicinal Indonesian plant, is described. First, the synthesis of (±)-eleutherol has been ­accomplished in nine steps starting from bromo methoxy aldehyde with the aid of diazo-transfer chemistry approach. Second, a metal-­catalyzed intramolecular cyclization reaction of the corresponding ­diazonaphthoquinone led to the desired eleuotherol, which served as a precursor to eleuthoside A. Then, several glycosidation routes, using different glucosyl donors, were experimented to reach effective O-glycosidation of eleutherol. The only successful strategy involved Koenigs–Knorr glycosidation using peracetyl glycosyl bromide in the presence of Ag 2 O and quinoline. This strategy furnished our desired acetylated glycoside of β-configuration, regioselectively. Finally, deacetylation and successive separation of diastereomers were conducted to give eleuthoside A.

中文翻译：

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Eleuthoside A 的全合成；Rh催化重氮萘醌分子内环化的应用

描述了从印度尼西亚药用植物中提取的天然细胞毒性物质 (±)-eleutherol 和 eleuthoside A 的首次全合成。首先，在重氮转移化学方法的帮助下，从溴甲氧基醛开始，(±)-eleutherol 的合成分九步完成。其次，金属催化的相应重氮萘醌的分子内环化反应产生所需的刺五加酚，其作为刺五加苷 A 的前体。然后，使用不同的葡萄糖基供体对几种糖苷化途径进行了实验，以实现刺五加酚的有效 O-糖苷化。唯一成功的策略涉及在 Ag 2 O 和喹啉存在下使用全乙酰糖基溴进行 Koenigs-Knorr 糖苷化。这种策略提供了我们想要的 β-构型乙酰化糖苷，区域选择性地。最后，进行非对映异构体的脱乙酰化和连续分离，得到 eleuthoside A。