Light-Induced Alkylation of (Hetero)aromatic Nitriles in a Transition-Metal-Free C-C-Bond Metathesis

A light-induced C-C-sigma-bond metathesis was achieved through transition-metal-free activation of an unstrained C(sp(3))-C(sp(3))-sigma-bond in 1-benzyl-1,2,3,4-tetrahydroisoquinolines. A photoredox-mediated single-electron oxidation of these precursor amines yield-radical cations which undergo a homolytic cleavage of a C(Sp(3))-C(sp(3))-sigma-bond rather than the well-known alpha-C-H-scission. The resulting carbon-centered radicals are used in the ipso-substitution of (hetero)aromatic nitriles proceeding through another single-electron transfer-mediated C-C-bond cleavage and formation.