13-Step Total Synthesis of Atropurpuran Shengling Xie Gui Chen Hao Yan Jieping Hou Yongping He Tongyun Zhao Jing Xu 10.1021/jacs.9b00391.s001 https://acs.figshare.com/articles/journal_contribution/13-Step_Total_Synthesis_of_Atropurpuran/7732598 Herein, we report a concise total synthesis of atropurpuran, a unique and synthetically challenging pentacyclic diterpene that bears a tetracyclo­[5.3.3.0<sup>4,9</sup>.0<sup>4,12</sup>]-tridecane skeleton that is unprecedented among natural terpenes. This 13-step approach features a strategy that include early stage rapid skeleton formation and the late-stage introduction of reactive functional groups, thus allowed a high overall synthetic efficiency with minimal use of PGs. The key transformations of our work include a facile construction of the spiro[5.5]­undecane moiety through an ring-closing enyne metathesis reaction and an efficient formation of the tetracyclo­[5.3.3.0<sup>4,9</sup>.0<sup>4,12</sup>]-tridecane scaffold via an regioselective double oxidative dearomatization/intramolecular Diels–Alder reaction cascade. This efficient approach should also inspire further advances in the synthesis of related complex diterpenes and diterpenoid alkaloids. 2019-02-13 00:00:00 ring-closing enyne metathesis reaction tetracyclo oxidative dearomatization cascade diterpenoid alkaloids moiety tridecane PG spiro Atropurpuran Herein synthetically late-stage introduction strategy reactive atropurpuran skeleton formation scaffold .0 advance pentacyclic diterpene transformation synthesis Diel efficiency 13- step approach features regioselective 13- Step construction Synthesi