Retigeranic acid A is a uniquely structured pentacyclic sesterterpene bearing eight stereogenic centers. We report a concise route to the core structure of (−)-retigeranic acid A. The stereochemistry of its six chiral centers and three quaternary carbon centers was well-controlled. This route features two intramolecular Pauson–Khand reactions (IMPKRs): the first forged the D and E rings to deliver the triquinane subunit, and the second constructed the A and B rings and diastereoselectively installed the quaternary C_6a center.

中文翻译：

---

(-)-Retigeric Acid A 核心结构的合成路线

Retigeric acid A 是一种结构独特的五环二萜，带有八个立体中心。我们报告了 (-)-retigeric acid A 核心结构的简洁路线。其六个手性中心和三个季碳中心的立体化学得到了很好的控制。该路线具有两个分子内 Pauson-Khand 反应 (IMPKR)：第一个锻造 D 和 E 环以传递三喹烷亚基，第二个构建 A 和 B 环并非对映选择性地安装四元 C _6a中心。