Overcoming the Potential Window-Limited Functional Group Compatibility by Alternating Current Electrolysis.

The functional group compatibility of an electrosynthetic method is typically limited by its potential reaction window. Here, we report that alternating current (AC) electrolysis can overcome such potential window-limited functional group compatibility. Using alkene heterodifunctionalization as a model system, we design and demonstrate a series of AC-driven reactions that add two functional groups sequentially and separately under the cathodic and anodic pulses, including chloro- and bromotrilfuoromethylation as well as chlorosulfonylation. We discovered that the oscillating redox environment during AC electrolysis allows the regeneration of the redox-active functional groups after their oxidation or reduction in the preceding step. As a result, even though redox labile functional groups such as pyrrole, quinone, and aryl thioether fall in the reaction potential window, they are tolerated under AC electrolysis conditions, leading to synthetically useful yields. The cyclic voltammetric study has confirmed that the product yield is limited by the extent of starting material regeneration during the redox cycling. Our findings open a new avenue for improving functional group compatibility in electrosynthesis and show the possibility of predicting the product yield under AC electrolysis from voltammogram features.

Controlling One- or Two-Electron Oxidation for Selective Amine Functionalization by Alternating Current Frequency.

Here, we report a unique electrosynthetic method that enables the selective one-electron oxidation of tertiary amines to generate α-amino radical intermediates over two-electron oxidation to iminium cations, providing easy access to arylation products by simply applying an optimal alternating current (AC) frequency. More importantly, we have discovered an electrochemical descriptor from cyclic voltammetry studies to predict the optimal AC frequency for various amine substrates, circumventing the time-consuming trial-and-error methods for optimizing reaction conditions. This new development in AC electrolysis provides an alternative strategy to solving challenging chemoselectivity problems in synthetic organic chemistry.

Revisiting Alternating Current Electrolysis for Organic Synthesis.

This review summarizes the recent advancements in alternating current (AC)-driven electroorganic synthesis since 2021 and discusses the reactivities AC electrolysis provides to achieve new and unique organic transformations.

Alternating Current Electrolysis for Organic Electrosynthesis: Trifluoromethylation of (Hetero)arenes.

Paired electrolysis has a limited reaction scope for organic synthesis because it is often not compatible with reactions involving short-lived intermediates. We addressed this limitation using alternating current electrolysis (ACE). Using trifluoromethylation of (hetero)arenes as a model reaction, we showed that the yield was improved from 13% using paired electrolysis to 84% using ACE. We have also developed a theory for guiding the rational design of reaction parameters for future applications of ACE.