Electrochemical aromatic C–H pyridination: A facile route to N-aryl pyridinium salts

N -Aryl pyridinium salts are versatile synthetic intermediates that function as masked primary arylamines and as building blocks for cationic nitrogen–doped functional π-electronic materials. This review explores the electrochemical routes to N -aryl pyridinium salts via direct anodic aromatic C–H oxidation, which does not require prefunctionalized substrates, stoichiometric chemical oxidants, or transition-metal catalysts. The reaction mechanism and the self-limiting character of the pyridinium salt product, which suppresses overoxidation and ensures high chemoselectivity, are discussed. The broad substrate scope, ranging from electron-rich arenes to electron-deficient and halogenated substrates, enabled by boron-doped diamond electrodes and continuous-flow microreactors, is examined. Synthetic applications are summarized, including arylamine synthesis via Zincke aminolysis, extension to imidazole and heterocyclic nitrogen nucleophiles, intramolecular cyclization for the synthesis of benzoxazoles, benzothiazoles, and cationic nitrogen–doped polycyclic aromatic hydrocarbons, and functionalization of π-conjugated polymers and graphitic carbon materials. These advances establish anodic C–H pyridination as a powerful and sustainable platform for C–N bond formation in organic and materials chemistry.