β-Scission by Direct Electrochemical Oxidation: Proton-coupled Electron Transfer Mechanism Dictated by Synthetic Study and Computations

Abstract

β-Scission from alkoxy radical enables selective Csp3-Csp3 bond cleavage under ambient conditions, offering a useful method for organic synthesis. Various photocatalytic systems for β-scission have been reported, where proton-coupled electron transfer (PCET) mechanism plays a key role in the generation of alkoxy radical and thus β-scission. Electrochemical β-scission has been mainly pioneered in the presence of mediator, and a direct electrochemical system has rarely been investigated. Here, we investigated the β-scission via direct electrochemical oxidation using a model compound with β-O-4 linkage. Synthetic experiments suggested smooth progress of β-scission in the presence of collidine as a base. Cyclic voltammetry measurement, voltammetric simulation, and quantum simulation suggested the PCET mechanism is responsible for the electrochemical reaction, which is followed by β-scission process. This report provides fundamental insights into the electrochemical β-scission via direct electron transfer on the electrode, which contribute to future applications such as biomass valorization.

Keywords

• β-scission
• csp3-csp3 bond cleavage
• electrochemical proton-coupled electron transfer
• cyclic voltammetry simulation