In this study, we present a novel single-carbon insertion approach via a distonic radical cation intermediate by electrochemical oxidation (Figure ). We utilize α-H diazo ester as the carbon source, which formally yields a carbynyl anion equivalent following denitrogenation and deprotonation. While the nucleophilic reactivity of α-H diazo ester, such as ethyl diazoacetate (EDA), toward radical cation species is documented, the oxidative single-carbon insertion and ring expansion with α-H diazo ester have not been previously reported. It is noteworthy that ring expansion reactions via single-carbon insertion using electrochemistry have only been reported once. This instance, dating back to 1972, involved a reaction of 2,3,4,5-tetrakis(4-methoxyphenyl) pyrrole, where nitromethane solvent serves as the carbon source for single-carbon insertion at the meta-position.