The first total synthesis of daphgraciline has been achieved, which also represents the first example of the synthesis of Daphniphyllum yuzurine-type alkaloids (∼50 members). The unique bridged azabicyclo[4.3.1] ring system in the yuzurine-type subfamily was efficiently and diastereoselectively assembled via a mild type II [5+2] cycloaddition for the first time. The compact tetracyclic [6–7–5–5] skeleton was installed efficiently via an intramolecular Diels–Alder reaction, followed by a benzilic acid-type rearrangement. The synthetically challenging spiro tetrahydropyran moiety in the final product was installed diastereoselectively via a Ti^III-mediated reductive epoxide coupling reaction. Potential access to enantioenriched daphgraciline is presented.

中文翻译：

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Yuzurine型生物碱Daphgraciline的全合成

实现了daphgraciline的首次全合成，这也代表了Daphniphyllum yuzurine型生物碱（~50个成员）合成的第一个例子。yuzurine 型亚家族中独特的桥联氮杂双环[4.3.1] 环系统首次通过温和的 II 型 [5+2] 环加成反应高效且非对映选择性地组装。紧凑的四环 [6-7-5-5] 骨架通过分子内 Diels-Alder 反应有效安装，然后进行苯甲酸型重排。最终产品中具有合成挑战性的螺四氢吡喃部分通过 Ti ^III介导的还原性环氧化物偶联反应非对映选择性地安装。介绍了获得对映体富集 daphgraciline 的潜在途径。