Electroredox Carbene Organocatalysis with iodine cocatalyst

Oxidative carbene organocatalysis, inspired from Vitamin B1 catalyzed oxidative activation from pyruvate to acetyl coenzyme A, have been developed as a versatile synthetic method. To date, the α-, β-, γ-, δ- and carbonyl carbons of (unsaturated)aldehydes have been successfully activated via oxidative N-heterocyclic carbene (NHC) organocatalysis. In comparison with chemical redox or photoredox methods, electroredox methods, although widely used in mechanistic study, were much less studied in NHC catalyzed organic synthesis. Herein, an electroredox NHC organocatalysis system with iodine cocatalyst was developed. With the help of non-uniform distribution of electrolysis system, NHC and iodine, which was normally not compatible in chemical reaction, cooperated well in the electrochemical system. This cocatalyst system provided general solutions for electrochemical single-electron-transfer (SET) oxidation of Breslow intermediate towards versatile transformations. Radical clock experiment and cyclic voltammetry results suggested an anodic radical coupling pathway.