Based on these findings, we propose the reaction mechanism (Figure ). First, radical cations of the substrates are formed through single-electron oxidation at the anode. Subsequently, nucleophilic attack of diazo esters, followed by N2 elimination, yields cyclopropane-containing radical cation intermediate species. The reversible transformation of these species occurs through the generation of distonic radical cations, facilitating carbon-atom migration under ambient conditions. The insertion position is determined by kinetic control, where ΔG ‡ depends on the electronic structure of the aromatic ring controlled by PG. Subsequent one-electron oxidation, deprotonation, and hydrolysis produce pyridines as the final product.