Advances in Copper-Catalyzed CC Coupling Reactions and Related Domino Reactions Based on Active Methylene Compounds

Active methylene compounds are a major class of reaction partners for CC bond formation with sp2 CX (X=halide) fragments. As one of the most‐classical versions of the Ullmann‐type coupling reaction, activated‐methylene‐based CC coupling reactions have been efficiently employed in a large number of syntheses. Although this type of reaction has long relied on noble‐metal catalysis, the renaissance of copper catalysis at the end of last century has led to dramatic developments in Ullmann CC coupling reactions. Owing to its low cost, abundance, as well as excellent catalytic activity, the exceptional atom economy of copper catalysis is gaining widespread attention in various organic synthesis. This review summarizes the advances in copper‐catalyzed intermolecular and intramolecular CC coupling reactions that use activated methylene species as well as in tandem reactions that are initiated by this transformation. A bent copper: Copper catalysis is rapidly becoming a highly efficient and useful economical option in Ullmann coupling reactions and, in particular, the activated‐methylene‐based CC coupling reaction is gaining increasing attention. This review considers the recent advances in the copper‐catalyzed intermolecular‐ and intramolecular CC coupling reactions of active methylene and the tandem reactions involving this coupling reaction.