Photocatalytic Radical Functionalization of Alkenylammonium Salts.

Alkenylammonium salts are introduced as an underdeveloped class of electron-deficient radical acceptors. Under visible-light photoredox catalysis combined with halogen atom transfer (XAT) or hydrogen atom transfer (HAT) activation modes, these cationic alkenes react with a broad range of alkyl radical precursors. The transformation enables the modular construction of structurally diverse quaternary ammonium compounds under mild conditions. The synthetic utility of the protocol is demonstrated through cyclopropanation, late-stage functionalization, and one-pot demethylation to access tertiary amines. This work establishes alkenylammonium salts as versatile building blocks in catalytic radical chemistry, thereby expanding the synthetic strategies for the preparation of quaternary ammonium salts and tertiary alkylamines.