Organocatalytic nitrogen transfer to C=C bonds provides straightforward access to aziridines under mild conditions with low financial and environmental impacts; however, previous methods were typically limited to conjugated C=C bonds (that is, activated olefins), whereas aziridination of isolated C=C bonds (that is, unactivated olefins) remains underexplored. Here we demonstrate a strategy for nitrogen transfer to unactivated olefins by utilizing electron-deficient ketones as catalysts. An oxaziridine intermediate, generated in situ from the ketone catalyst and a nitrogen source, transfers nitrogen to unactivated C=C bonds preferentially over activated C=C bonds. This ‘unusual’ chemoselectivity, as well as the enantioselectivity realized through the use of a chiral ketone catalyst, cannot be achieved by previously developed methods that are based on either organocatalysts or metal catalysts. Moreover, mechanistic studies through modified mass spectrometry allow capture and further investigation of the transient oxaziridine intermediate, establishing its essential role in this nitrogen transfer process.

有机催化氮转移至C = C键可在温和条件下直接获得氮丙啶，而对财务和环境的影响很小；但是，以前的方法通常仅限于共轭C = C键（即活化的烯烃），而孤立的C = C键（即未活化的烯烃）的叠氮化仍未得到充分研究。在这里，我们展示了利用缺电子的酮类作为催化剂将氮转移至未活化烯烃的策略。由酮催化剂和氮源原位产生的恶唑烷中间体比活化的C = C键优先转移氮到未活化的C = C键。这种“不寻常的”化学选择性以及通过使用手性酮催化剂实现的对映选择性，以前开发的基于有机催化剂或金属催化剂的方法无法实现。此外，通过改进的质谱仪进行的机理研究允许捕获和进一步研究瞬态恶唑烷中间体，从而确定其在氮转移过程中的重要作用。