Intermolecular Aza Paternò-Büchi Reaction of <i>N</i> -(Fluorosulfonyl)imines and Triplet-State Aromatic Alkenes

Intermolecular aza Paternò-Büchi reaction between N-(fluorosulfonyl)imines and aromatic alkenes has been developed through the photoinduced generation of a triplet state of the aromatic alkene. The N-fluorosulfonyl group proved crucial in enabling this transformation to furnish azetidines, as no product formation was observed in the reaction using N-tosylimines. Theoretical studies revealed that the highly electrophilic fluorosulfonyl-substituted nitrogen facilitates efficient nitrogen–carbon bond formation with triplet-state styrenes. Furthermore, by taking advantage of facile derivatization of the fluorosulfonyl group, we demonstrated its reductive deprotection to generate unprotected azetidines.