Photosensitizer-Free Photoinduced Ground-State Triplet Carbene-Assisted Persistent Aryloxy Radical Generation via Hydrogen Atom Transfer

The traditional intermolecular O–H insertion strategy is typically associated with the reactivity exhibited by the singlet spin state, or it can alter the spin state from triplet to singlet by hydrogen bonding. Herein, we report diazoarylidene succinimide that generates a persistent ground-state triplet carbene under visible light (Blue LED, 456 nm) without a photosensitizer. This triplet carbene undergoes an intramolecular O–H insertion via hydrogen atom transfer, forming a persistent aryloxy radical without altering its spin state and leading to biologically relevant 2H-chromenes.