Aromatic C(sp2)−H Functionalization by Consecutive Paired Electrolysis: Dibromination of Aryl Amines with Dibromoethane at Room Temperature.

Herein, we disclose a facile and efficient electrochemical method for the dibromination of aryl amines by double functionalization of aromatic C(sp2)−H (both para and ortho) under metal‐ and external oxidant‐free conditions at room temperature for the first time. The reaction is demonstrated using 1,2‐dibromoethane to dibrominate a wide range of N‐substituted aryl amines in a simple setup with C(+)/Pt(−) electrodes under mild reaction conditions. This transformation proceeds smoothly with a broad substrate scope affording the valuable and versatile N‐substituted 2,4‐dibromoanilines in moderate to excellent yields with high regioselectivity. In this paired electrolysis, cathodic reduction of 1,2‐DBE followed by anodic oxidation generates bromonium intermediates, which then couple with anilines to furnish the dibrominated products. It represents a distinctive approach to challenging redox‐neutral reactions. The versatility of the electrochemical ortho‐, para‐dibromination was reflected by unique regioselectivities for challenging aryl amines and gram‐scale electrosynthesis without the use of a stoichiometric oxidant or an activating agent. [ABSTRACT FROM AUTHOR]