Deciphering Mechanistic Pathways and Selectivity in Electrochemical Oxidative C–N Bond Formation between Olefins and Sulfonamides

Electrochemical oxidative C-N bond formation of olefins provides a sustainable route to nitrogen-containing molecules, enabling direct C-N bond formation under oxidant- and metal-free conditions. Despite recent progress, the mechanistic diversity of these reactions and the factors governing pathway selectivity remain poorly understood. Herein, we show that the relative oxidation potentials of olefins and sulfonamides dictate distinct C-N bond-forming modes: nucleophilic attack of sulfonamides on olefin radical cations when the olefin is more readily oxidized, nitrogen radical addition when the sulfonamide is preferentially oxidized, and radical-radical cross-coupling when the redox properties are comparable. In situ electrochemical electron paramagnetic resonance spectroscopy provides direct structural evidence for key radical intermediates, offering rare mechanistic insight into these transformations. Guided by this framework, we developed an electrochemical annulation that affords pyrrolidines and an allylic C-N bond formation process, demonstrating the synthetic utility of pathway control. By correlating substrate redox properties with reactivity outcomes, this work establishes principles for selectivity in the electrochemical olefin C-N bond formation reaction and demonstrates the broader potential of electrochemistry in efficient C-N bond construction.