Electrochemical Access to Functionalized Benzofurans via Versatile Radical-Polar Crossover Carbo-Cyclizations

Highly functionalized benzofurans represent omnipresent biorelevant compounds of practical importance in the pharmaceutical industry and material sciences. Electrochemistry provides a platform for enabling redox-neutral transformations via single-electron transfer (SET), analogous to visible-light photocatalysis, while eliminating the need for costly photocatalysts and offering inherent tunability through adjustable redox potentials. Herein, we report a radical-polar crossover for isohypsic electrosynthesis to access functionalized benzofurans in a resource-economical manner. Thus, easily accessible alkenyl-tethered arenediazonium salts were converted with the aid of soft Lewis bases after intramolecular radical carbo-cyclization. A broad scope of substrates, including a variety of otherwise sensitive different substituents, proved to be viable.