Se-Aryl-N-phenylphenoselenazinium salts: aryl radical precursors incorporating a photosensitizer unit

Se-Aryl-N-phenylphenoselenazinium salts were synthesized as triarylselenonium salts incorporating a photosensitizer unit. Under blue-light irradiation, these served as aryl radical precursors, yielding arylphosphonates, phenol, and phenylboronic ester. The reaction mechanism was investigated by spectroscopic methods, which suggests that the aryl radical formation proceeds through intramolecular charge transfer and intermolecular photoredox cycles.