Synthetic Organic Electrolysis Using Catalysts

In the past decades, synthetic organic electrolysis has attracted much attention as an excellent tool for organic synthesis due to its potent and irreversible electron transfer between electrodes and organic compounds. While developing new reactions using organic electrolysis, we are investigating the concept of catalyst-supported organic electrolysis. The first strategy is the generation of bromenium ions (Br+) via anodic oxidation and the oxidative transformation of indole compounds. We found that the semi-pinacol rearrangement of tetrahydrocarbolines proceeded with Br+ generated by the anodic oxidation. The anodic oxidation of tetrahydrocarbazole did not give spiro compounds under similar conditions, but instead the aromatization proceeded to afford carbazoles. This transformation required both the bromide and the lithium-ion. The second strategy is organic electrolysis promoted by the catalytic amount of electricity. The reactions that are completed by the catalytic amount of electricity can be categorized as hole- or electron-catalyzed transformations. Moreover, these reactions can be achieved using an electrochemical flow reactor, which enables efficient processes. The numerical parameters in the electrochemical flow system, such as the current values and the flow rate, were optimized using the Gaussian process regression. This machine-learning method suggested better reaction conditions with a small number of experiments.