Spin-Selective Generation of Triplet Nitrenes: Olefin Aziridination through Visible-Light Photosensitization of Azidoformates

Azidoformates are interesting potential nitrene precursors, but their direct photochemical activation can result in competitive formation of aziridination and allylic amination products. Herein, we show that visible‐light‐activated transition‐metal complexes can be triplet sensitizers that selectively produce aziridines through the spin‐selective photogeneration of triplet nitrenes from azidoformates. This approach enables the aziridination of a wide range of alkenes and the formal oxyamination of enol ethers using the alkene as the limiting reagent. Preparative‐scale aziridinations can be easily achieved under continuous‐flow conditions. Mit Spin zu Heterocyclen: Nützliche photochemische Aziridinierungen mithilfe eines durch sichtbares Licht aktivierten Übergangsmetall‐Photosensibilisators liefern Nitrene ausschließlich in ihrem Triplett‐Spinzustand. Verschiedene aliphatische und aromatische Alkene werden glatt und ohne konkurrierende allylische Insertionen aziridiniert. TrocN3=2,2,2‐Trichlorethylazidoformiat.