Transition-Metal-Free Anti-Markovnikov Hydroarylation of Alkenes with Aryl Chlorides through Consecutive Photoinduced Electron Transfer

Abstract

The hydroarylation of alkenes has emerged as a powerful strategy for arene functionalization. However, aryl chlorides remain a large challenge in this type of reaction due to the chemical inertness of the C(sp 2 )−Cl bond and high negative reduction potential. Herein, we report an anti-Markovnikov radical hydroarylation of alkenes with aryl chlorides via visible-light photoredox catalysis. The key reactive aryl radicals can be efficiently achieved from aryl chlorides by consecutive photoinduced electron transfer. This transition-metal-free protocol features mild conditions, a wide substrate scope, and functional group tolerance, producing a diverse range of linear alkylarenes in moderate to good yields. The reaction is proposed to proceed through a radical-polar crossover pathway.

Triple Radical Sorting: Aryl-Alkylation of Alkenes

“…Traditionally, alkenes have been coupled with aryl halides through the venerable Heck or reductive Heck reactions to form single C–C bonds. , A notable advantage of alkenes, however, is the fact that they possess two potential sites of functionalization that could be harnessed for the rapid buildup of molecular complexity. Recently introduced radical-based strategies have expanded the scope of aryl-alkene coupling and have permitted aryl-heteroatom difunctionalization of alkenes − (Figure a). To date, however, methods that capitalize on the susceptibility of alkenes to difunctionalization as a means to achieve simultaneous formation of multiple C–C bonds remain underdeveloped.…”