Catalytic photoactivation of a triarylamine electron donor-acceptor complex for difunctionalization of alkenes

Abstract

The photoactivation of electron donor-acceptor complexes is a useful tool for the generation of radical species in synthetic chemistry. However, alkene difunctionalization via catalytic donor-acceptor complexes remains less developed. Herein, we report a versatile catalytic photoactivation of an electron donor-acceptor complex platform for the difunctionalization of alkenes without a need for precious transition metal catalysts or synthetically elaborate organic dyes. By taking advantage of the visible light potential of aggregates between triarylamines and S-fluoromethyldiaryl sulfonium salts, photoinduced single-electron transfer is initiated to generate a stable radical cation, which acts as an endogenous oxidant to convert the radical addition intermediate into a cationic species. Subsequent N-nucleophilic addition enables the difunctionalization of styrenes. This general photocatalyst-free protocol is applied to fluoroalkylative sulfonamidation, amidation, hydrazidation, azidation, and anilination reactions under mild conditions.