Photoredox catalytic intramolecular imine C–H bond functionalization using ligand free Cu(ii) salts

Photocatalysis is a powerful method for organic synthesis because of the lack of side products/waste materials and high efficiency, but suitable reaction types are still underexplored. Inspired by the function of a directing group for C-H bond activation, we induce the directing group notion into photocatalysis to activate the C-H bond through light treatment only if any metal-directing group complexes are photoinitiators. Herein, we found that conjugated N, O-bidentate copper(II) complexes were novel photoinitiators, and thereby could be used as the directing group to activate their intramolecular imine C(sp(2))-H to produce the corresponding cyclized products via a UV triggered free radical mechanism.