Transient N-Aziridinyl Radicals in Olefin Functionalization

Aziridines are the smallest nitrogen-containing heterocycles and are responsible for the biological activity of aziridine-natural products and active pharmaceutical ingredients (APIs). Classically, aziridines are prepared from acyclic precursors via 1) [2+1] cycloaddition of a nitrene equivalent with an olefin, 2) [2+1] cycloaddition of a carbene equivalent with an imine, or 3) via intramolecular cyclization of β-functionalized amines. In comparison, introduction of intact aziridines is an uncommon disconnection. Here, we highlight the recent development of N-aziridinyl radicals as novel intermediates in synthetic chemistry that enable olefin hydroxyaziridination. These intermediates, generated by photoredox activation of N-pyridinium aziridine precursors, afford access to products of a heretofore unknown epoxide opening with N-aziridine nucleophiles and introduce new disconnections of olefin aziridination chemistry.