Electrocatalytic synthesis: an environmentally benign alternative for radical-mediated aryl/alkenyl C(sp2)–C(sp3) cross-coupling reactions

Abstract

C(sp²)–C(sp³) bonds comprise the fundamental skeletons of many organic molecules, making their construction one of the most important transformations in synthetic chemistry. Over the past decades, radical-based C(sp²)–C(sp³) cross-coupling reactions have emerged as a straightforward and powerful tool to rapidly increase molecular complexity for numerous applications in biomedical science, chemistry, and materials science. Electrochemistry is regarded as a synthetically appealing alternative to drive redox reactions in a selective and environmentally benign manner. With the flourishing development of organic electrosynthesis, remarkable achievements have been witnessed in radical-mediated aryl/alkenyl C(sp²)–C(sp³) cross-coupling reactions for the synthesis of diverse alkylated (hetero)arenes and 1,2-disubstituted alkenes. In these reactions, the generation of alkyl radicals and their orderly transformation are the keys to success. This review comprehensively summarizes recent progress in electrochemically initiated radical-mediated C(sp²)–C(sp³) cross-coupling reactions, emphasizing the key electrochemically induced step for the generation of alkyl radical species, the scope and limitations of the C(sp²) and C(sp³) coupling partners, and the underlying reaction mechanisms.