Organo-mediator enabled electrochemical 1,4-aryl migration of N-aryl-2-iodobenzamides/N-sulfonyl-2-iodoanilines to access biaryls

Abstract

Herein, an electroreductive radical 1,4-aryl migration of N-aryl-2-iodobenzamides/N-sulfonyl-2-iodoanilines promoted by catalytic amounts of 9-bromophenanthrene as a redox mediator is described. This protocol proceeds smoothly in an undivided cell under mild conditions, producing a wide range of structurally versatile biaryls in moderate to good yields without any transition metal catalysts, chemical reductants, or sacrificial anodes. Preliminary mechanistic studies revealed that the generation of aryl radicals via cathodic single-electron reduction is crucial, with sequential intramolecular 5-exo-trig spirocyclization, C–N bond cleavage, and hydrogen atom abstraction.