Discovery of Anodic Thiourea Oxidation as a Sustainable Counter Reaction to Boost Electro-Reductive Organic Transformations

In the reductive electrochemistry, the oxidative counter reaction remains one of the main bottlenecks for efficient cathodic organic transformations, but it has received less attention. Herein, anodic thiourea (TU) oxidation is reported as a sustainable oxidative counter reaction, which takes place at a low potential with a relative high current density. Mechanistic studies suggest that the anodic TU oxidation is initiated by a single electron-transfer (SET) process with the formation of formamidine disulfide cation as the main intermediate. In practice, the anodic TU oxidation counterbalances a series of SET reductive transformations at the cathode, and the protocol features sustainable condition, minimized waste, convenient setup, and excellent scalability, which highlights the underexplored potential of TU oxidation as an alternative counter reaction for the reductive electrochemistry.