Intramolecular, Visible-Light-Mediated Aza Paternò-Büchi Reactions of Unactivated Alkenes.

Azetidines are of particular interest in medicinal chemistry for their favorable properties, including increased resistance to oxidative metabolism and lower lipophilicity. The recent development of [2 + 2] reactions has significantly expanded the limited repertoire of methods for azetidine synthesis, but access to more complex architectures still requires further development. Herein, we report a visible-light-enabled intramolecular [2 + 2] cycloaddition of unactivated alkenes that proved previously unreactive to access tricyclic azetidines with 3D complex structures and high levels of saturation.