Electron
donor–acceptor (EDA) complex-mediated single-electron
transfer (SET) is a crucial method for generating carbon radicals.
Hydrogen atom transfer (HAT) enables the direct generation of alkyl
radicals. We report a dual-role EDA-SET/HAT photoreaction system for
carbon–carbon bond formation using a phenol catalyst and aryl
iodide. This system facilitates addition of alkyl radicals generated
from ethers, amide, sulfide, and cycloalkane to arenes. Mechanistic
studies revealed that EDA complex formation is mediated by halogen
bonding between phenoxide and aryl iodide. Irradiation of the EDA
complex with visible light generates an aryl radical, which abstracts
a hydrogen atom from an sp3 carbon to form an alkyl radical.