Electrochemical oxidation enables aromatic C-H amination with dual mechanisms

The selective amination of aromatic C-H bonds is a powerful strategy to access aryl amines, which offer functionalities used in many pharmaceuticals and agrochemicals. Despite advances in the field, a general platform for the direct, selective C-H amination of electronically diverse arenes, particularly electron-deficient (hetero)arenes, remains an unaddressed challenge. In addition, many (hetero)arenes are reluctant to undergo common selective prefunctionalization reactions, including halogenation, borylation and silylation. Here we report an electrochemical method for the selective C-H amination of a range of (hetero)arenes. Key to this strategy is mechanistic flexibility with convergent outcomes between anodic generation of electrophilic nitrogen radical dications from DABCOnium salts (DABCO = 1,4-diazabicyclo[2.2.2]octane) and arene radical cations from electron-rich arenes. Notably, oxidative conditions allow the electrocatalytic regeneration of DABCOnium salts that can participate in the functionalization of electron-deficient (hetero)arenes. This platform allows anodically generated N-radical cations to engage in aromatic C-H amination instead of well-reported hydrogen-atom transfer. This electrochemical DABCOylation reaction yields aryl DABCOnium salts that provide access to many complex drug-like aryl piperazines with high functionality tolerance, broad scope and site selectivity. Moreover, these salts can engage in catalytic functionalization reactions to form C-C, C-P and C-B bonds.