In this communication, a nitroso-ene cyclization was devised to rapidly construct 1-azaspiro[4.4]nonane, a key structural motif which was further implemented into the modular synthesis of (±)-cephalotaxine (6). The whole synthesis route to access the key intermediate 7 involves eight steps from a commercially available 1,2-epoxycyclopentane (12) and five purifications on silica gel column. The direct nitroso-ene reaction to 1-azabicyclo[4.4]non-2-one paves a way to a future development of the practical synthesis of cephalotaxus alkaloids.

中文翻译：

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亚硝基环化使得能够获得1-azaspiro [4.4]壬烷及其在（±）-头孢他辛模块化合成中的应用

在这种交流中，设计了亚硝基烯环化反应以快速构建1-azaspiro [4.4]壬烷，这是一个关键的结构基序，该基序被进一步实现为（±）-头孢他辛的模块化合成（6）。进入关键中间体7的整个合成路线涉及从市售1,2-环氧环戊烷（12）进行的八个步骤，以及在硅胶柱上进行五个纯化。与1-氮杂双环[4.4]非-2-酮的直接亚硝基反应为将来合成头孢类生物碱的发展铺平了道路。