Cobalt-catalyzed cross-electrophile couplings: from electrosynthesis to conventional chemistry

Cobalt-catalyzed reductive cross-couplings, also known as cross-electrophile couplings (XECs), have emerged as a valuable and sustainable alternative to classical cross-coupling strategies. Unlike traditional methods relying on preformed organometallic reagents, cobalt catalysis enables the direct coupling of two electrophiles, offering broad functional group tolerance, access to diverse C(sp 2 )–C(sp 2 ), C(sp 2 )–C(sp 3 ), and C(sp 3 )–C(sp 3 ) bonds, and compatibility with mild conditions. Building on early electrochemical studies, significant progress has been made in both electrosynthesis (eXEC) and conventional approaches (XEC), highlighting cobalt’s cost-effectiveness, ecological advantages, and complementary reactivity compared to nickel. This account summarizes the development of cobalt-catalyzed reductive cross-couplings, from pioneering contributions to recent advances, with emphasis on mechanistic aspects and substrate scope.