A Ni-catalyzed (4 + 2) cycloaddition of alkynes and azetidinones toward piperidinones was used as key reaction in the enantioselective synthesis of naturally occurring indolizidine alkaloids. The reaction benefits from the use of an easily accessible azetidinone as an advanced and divergent intermediate to build the indolizidine core. This methodology has been applied in the total syntheses of (+)-septicine, (+)-ipalbidine, and (+)-seco-antofine to illustrate the applicability of the general approach.

中文翻译：

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通过镍催化的（4 + 2）环化合成吲哚并咪唑生物碱。

炔烃和氮杂环丁酮向哌啶子酮的Ni催化（4 + 2）环加成反应是天然吲哚并立定生物碱的对映选择性合成的关键反应。该反应得益于使用容易获得的氮杂环丁酮作为先进且发散的中间体来构建吲哚并立定核心。此方法已应用于（+）-败血碱，（+）-依帕立定和（+）-seco-antofine的总合成中，以说明通用方法的适用性。