Electrochemical oxidative dearomatization of electron-deficient phenols using Br+/Br- catalysis

Chem Commun (Camb). 2025 Jan 10. doi: 10.1039/d4cc06472k. Online ahead of print.

Abstract

An electrochemical method for the oxidative dearomatization of electron-deficient phenols by employing tetrabutylammonium bromide as a mediator under aqueous biphasic conditions is reported. This approach represents a safer alternative to the use of stoichiometric chemical oxidants and enables oxidative dearomative spirolactonization and spiroetherification reactions. Compared to previous approaches based on direct electrolysis, this strategy expands the substrate scope to electron-deficient phenols. Cyclic-voltammetry analysis suggests that the bromide ions might be oxidized to Br2 or Br3- ions that are in equilibrium with the catalytically active hypobromite under aqueous conditions.