Electrocatalytic\nAnaerobic Oxidation of Benzylic Amines\nEnabled by Ferrocene-Based Redox Mediators

The generation and functionalization of carbon- or nitrogen-centered\nradicals are of great interest for their potential synthetic utility.\nHere, we report the anaerobic electrocatalytic oxidation of two primary\nbenzylic amines, benzylamine and 2-picolylamine, in the presence of\na catalytic quantity of an electron deficient ferrocene derivative\nas a single-electron redox mediator. The use of the appropriate redox\nmediator prevented fouling of the electrode surface and significantly\ndecreased the potential at which the catalytic oxidation reaction\noccurred. Simulation of the electrochemical results revealed an E<sub>r</sub>C<sub>i</sub>′ catalytic process between the redox\nmediator and both substrates and significant difference in the electron\ntransfer rate between the two substrates and electrochemically oxidized\nmediator. Through anaerobic controlled-potential electrolysis, we\ndemonstrated a method with a Faradaic efficiency of 90% forming the\ndesired coupled imine product of benzylamine oxidation while avoiding\nan excess of problematic overoxidation, hydrolysis, and other side\nreactions. Based on the electrochemical data along with the product\nanalyses using IR and <sup>1</sup>H and <sup>13</sup>C NMR spectroscopies,\nthe proposed mechanistic steps for the redox mediated electrocatalytic\nprocess were laid out.