Unraveling two pathways for NHPI-mediated electrocatalytic oxidation reaction

Two pathways for N-hydroxyphthalimide (NHPI)-mediated electrocatalytic oxidation using phenylacetate derivatives as template substrates were first reported for benzylic CH oxidation to oxygenated and non-oxygenated products. DFT calculation indicates that the hydrogen-atom transfer (HAT) process between phthalimido-N-oxyl (PINO) and substrate is a rate-determined step. Aromatic α-keto esters and 2-((1,3-dioxoisoindolin-2-yl)oxy)-2-aryl acetate obtained by cross-coupling between benzylic radical and PINO can be selectively synthesized through controlling the concentration of PINO radical. This method provides a deep understanding for selective weak CH oxidation using NHPI as redox mediator.