C19-diterpene alkaloids are a class of alkaloids with pharmacologically important activities having an intricately fused hexacyclic ABCDEF-ring system. Here we report expeditious assembly of the ACE-ring substructure 4a by applying a three-component coupling strategy. A radical-polar crossover reaction between an AE-ring radical precursor, a C-ring radical acceptor and an aldehyde was realized by the actions of Et₃B and O₂, resulting in the installation of three new stereocenters and extension of the carbon chain corresponding to the B-ring. As the ACE-ring 4a possesses the correct C4,11-quaternary and C10-tertiary carbons, 4a would serve as an advanced intermediate for constructing the entire C19-diterpene alkaloid structures.

中文翻译：

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C19-二萜生物碱的ACE环亚结构的三组分偶联方法。

C19-二萜生物碱是一类具有药理学重要活性的生物碱，具有复杂稠合的六环ABCDEF-环系统。在这里，我们报告通过应用三组件耦合策略快速组装ACE环子结构4a。通过Et ₃ B和O ₂的作用，实现了AE环自由基前体，C环自由基受体和醛之间的自由基-极性交叉反应，从而安装了三个新的立体中心并延伸了碳链对应于B环。由于ACE环4a具有正确的C4,11-季碳和C10-叔碳，因此4a将用作构建整个C19-二萜生物碱结构的高级中间体。