Hybridaphniphylline B (1) is a Daphniphyllum alkaloid possessing 11 rings and 19 stereocenters. Here we report the first total synthesis of 1 featuring a late-stage intermolecular Diels-Alder reaction of a fully elaborated cyclopentadiene and asperuloside tetraacetate. The diene was prepared on the basis of a scalable route to daphnilongeranin B (4). Claisen rearrangement of an allyl dienol ether was exploited as a key step; the subtle variation of the substrate and use of protic solvents suppressed the undesired Cope rearrangement. Daphniyunnine E (6) and dehydrodaphnilongeranin B (7), two congeners of 4, were also synthesized. The dienophile arose from (+)-genipin through glycosylation and lactonization. A one-pot protocol was developed for the diene formation and Diels-Alder reaction; one of the cycloadducts was converted into 1 through reductive desulfurization and global deacetylation.

中文翻译：

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杂合茶碱 B 的全合成

Hybridaphniphylline B (1) 是一种具有 11 个环和 19 个立体中心的水蚤生物碱。在这里，我们报告了 1 的第一次全合成，其特征是完全精心设计的环戊二烯和阿斯珀鲁糖苷四乙酸酯的后期分子间 Diels-Alder 反应。二烯是根据可扩展的 daphnilongeranin B 路线制备的 (4)。烯丙基二烯醇醚的克莱森重排被用作关键步骤；底物的细微变化和质子溶剂的使用抑制了不需要的 Cope 重排。还合成了 Daphniyunnine E (6) 和 dehydrodaphnilongeranin B (7)，即 4 的两个同源物。亲二烯体通过糖基化和内酯化从 (+)-京尼平产生。为二烯形成和 Diels-Alder 反应开发了一锅法；