Electrochemical Azolation of Electron-rich Fluoroarenes: A Controlled Redox Chain Unlocks C─N Bond-forming e-S_NAr

Nucleophilic aromatic substitution (S_NAr) reactions are critical methods for forming C─N bonds in synthetic campaigns, but limitations in electrophile electronics restrict access to a large portion of chemical space. Photochemical oxidation of fluoroarenes has emerged as an attractive strategy to activate fluoroarenes toward nucleophilic addition, but back-electron transfer to solution-phase reduced photocatalysts limit the scope and efficiency of these methods. Herein, we describe an electrochemical strategy to overcome this obstacle by spatially separating redox events at electrode surfaces, extending the lifetime of the activated electrophile and enabling the azolation of electron-rich alkoxyfluoroarenes. Through stabilization of the oxidized product with voltage control and HFIP solvent, the reaction proceeds with catalytic charge via a proposed uphill redox chain mechanism. A wide range of electron-rich fluoroarenes and azoles are tolerated-including those with orthogonal functional group handles. The redox catalytic nature of this e-S_NAr reaction enables energy and mass efficient syntheses and facile scaling in a simple batch setup.