π-Extended Iodoarene as an Electrochemical Mediator for Oxidative C-N Coupling: Reactions, Mechanism, and Kinetics

Herein, we present the design and application of π-extended iodoarenes for electrocatalytic C-N bond coupling reac-tions. The extended π-systems of such compounds lower the oxidation potentials and stabilize the radical cation states, thus facilitating the selective and efficient electrochemical generation of hypervalent iodine. The electrocatalytic C-N coupling reactions of various N-protected aminobiphenyl derivatives were achieved, including those of substrates with the tert-butoxycarbonyl protecting group, which has never been applied to electrochemical C-N coupling reactions. A mechanistic study suggests the presence of halogen-bonding interactions of the radical cation state of the iodoarene with Lewis bases, and the coordination of Lewis bases evidently promotes electrochemical oxidation to generate hypervalent iodine species. A kinetic study using foot-of-the-wave analysis (FOWA) was also employed for the first time to examine electrochemical hypervalent iodine catalysis.