兰州大学樊春安团队报道了ent-Kaurane-， ent-Atisane-， ent-Beyerane-， ent-Trachylobane-和ent-Gibberellane-型二萜的不对称发散合成。相关研究成果发表在2022年12月20日出版的国际学术期刊《美国化学会杂志》。

基于具有ent-kaurane和ent-trachylobane核的常见合成子的后期转化，开发了九种C8乙醇桥联二萜A1–A9（candol A、powerol、sicanadiol、epi-candol B、atisiene、ent-atisan-16α-ol、4-decoxy-4-methyl-GA12、tracinol和ent-beyerane）的不对称发散合成的通用策略。通过烯烃/烯酮的区域选择性和非对映选择性铁介导的氢原子转移（HAT）6-exo-trig环化和烯烃/酮的3-exo-tring环化，战略性地探索了关键先进的ent-kaurane-和ent-trachylobane型构建块的快速组装，显示了HAT引发反应中密集功能化多环底物与πC═C和πC═O体系多重反应性。

在快速构建了五个主要结构骨架（ent-kaurane-、ent-atisane-、ent-beyerane-、ent-trachylobane-和ent-gillellane型）之后，可以从容易获得的手性γ-环香叶醇1和已知的手性γ取代环己烯酮2，其中首次实现了candol A（A1，8步）、powerol（A2，9步）、sicanadiol（A3，10步）、epi-candol A（A4，8步步）、ent-atisan-16α-ol（A6，11步）和trachinol （A8，10步步）的对映选择性全合成。

附：英文原文

Title: Asymmetric Divergent Synthesis of ent-Kaurane-, ent-Atisane-, ent-Beyerane-, ent-Trachylobane-, and ent-Gibberellane-type Diterpenoids

Author: Xian-He Zhao, Le-Le Meng, Xiao-Tao Liu, Peng-Fei Shu, Cheng Yuan, Xian-Tao An, Tian-Xi Jia, Qi-Qiong Yang, Xiang Zhen, Chun-An Fan

Issue&Volume: December 20, 2022

Abstract: A unified strategy toward asymmetric divergent syntheses of nine C8-ethano-bridged diterpenoids A1–A9 (candol A, powerol, sicanadiol, epi-candol A, atisirene, ent-atisan-16α-ol, 4-decarboxy-4-methyl-GA12, trachinol, and ent-beyerane) has been developed based on late-stage transformations of common synthons having ent-kaurane and ent-trachylobane cores. The expeditious assembly of crucial advanced ent-kaurane- and ent-trachylobane-type building blocks is strategically explored through a regioselective and diastereoselective Fe-mediated hydrogen atom transfer (HAT) 6-exo-trig cyclization of the alkene/enone and 3-exo-trig cyclization of the alkene/ketone, showing the multi-reactivity of densely functionalized polycyclic substrates with πC═C and πC═O systems in HAT-initiated reactions. Following the rapid construction of five major structural skeletons (ent-kaurane-, ent-atisane-, ent-beyerane-, ent-trachylobane-, and ent-gibberellane-type), nine C8-ethano-bridged diterpenoids A1–A9 could be accessed in the longest linear 8 to 11 steps starting from readily available chiral γ-cyclogeraniol 1 and known chiral γ-substituted cyclohexenone 2, in which enantioselective total syntheses of candol A (A1, 8 steps), powerol (A2, 9 steps), sicanadiol (A3, 10 steps), epi-candol A (A4, 8 steps), ent-atisan-16α-ol (A6, 11 steps), and trachinol (A8, 10 steps) are achieved for the first time.

DOI: 10.1021/jacs.2c09985

Source: https://pubs.acs.org/doi/10.1021/jacs.2c09985