Cobalt‐Catalyzed Reductive Cross‐Coupling Reactions

Abstract Cobalt‐catalyzed carbon–carbon bond‐forming reactions are an essential class of reactions in organic synthesis. This economical and eco‐compatible attractive catalyst could replace, in some cases, the well‐established, expensive palladium and toxic nickel catalytic systems that still dominate the field. Moreover, the cobalt‐catalyzed cross‐electrophilic couplings are excellent tools to form CC bond, avoiding the synthesis of a stoichiometric organometallic species. Starting from electrophiles bearing different functional groups such as alkyl, alkenyl, and aryl halides, aryl triflates, alkenyl acetates, allyl acetates, and benzyl alcohols, different reactions have been developed efficiently by electrosynthesis or chemical processes. The conditions are generally mild, and good to excellent yields are obtained. No ligand or a commercial one is required. In the electrochemical process, an iron‐sacrificial anode is used, while manganese is the main reductant used in chemical processes. This chapter intends to demonstrate that cobalt‐catalyzed cross‐coupling reactions offer an excellent alternative to the usual catalysts and are sometimes superior. Some proposed mechanisms are also presented.