Recent Advances in Transition-Metal-Catalyzed <i>Cine</i> -Coupling Reactions

In recent years, the principles of cine-substitution have been reinvigorated through transition-metal-catalyzed cross-coupling reactions, offering a modern approach to site-selective molecular editing. Compared with traditional ipso-coupling, cine-coupling provides complementary advantages in regioselectivity and structural diversification, enabling bond formation at positions adjacent to the leaving group that are often inaccessible by conventional methods. These transformations frequently employ readily available aryl and alkenyl derivatives and, through unconventional mechanistic pathways, directly construct structurally distinct molecular frameworks. The mechanistic complexity of cine-coupling is particularly noteworthy: metal migration, radical intermediates, and dynamic rearrangements not only account for the different regioselectivity but also create opportunities for reaction discovery and catalyst design. Despite the growing number of reports, a unifying framework to control selectivity between ipso- and cine-coupling pathways remains lacking. This review summarizes the major classes of cine-coupling reactions of alkenyl and aryl derivatives, highlights their mechanistic features, and discusses recent synthetic applications, aiming to stimulate conceptual development and expand the scope of transition-metal-catalyzed molecular-editing strategies.