Transition metal-catalyzed electrochemical processes for C–C bond formation

Abstract

In this review article, the in situ formation of various organometallic reagents by electrochemical methods for addition (carbon–carbon bond) reactions is discussed. In this study, the organometallic complexes are formed by the insertion of a metal in an alkyl or allyl halide structure. Furthermore, the catalytic cycles of the studied metals on the surface of electrodes and in solutions may consist of oxidative addition, the reductive elimination of ligands, metal transformation, the production of metal ions, or cyclization processes. Different types of C–C bond formation, such as Csp²–Csp², Csp²–Csp³, and Csp³–Csp³, using transition metal-catalyzed and electrochemical approaches (organometallic electrochemistry) are discussed. Moreover, variety of metals, such as Zn, Ni, Sm, In, Mn, Ru, Pd, Fe, and Cr, are investigated as catalysts in the formation of C–C bonds between two organic compounds. High atom economy; excellent isolated yields; sustainability; scalability; one-pot, simple, and mild reaction conditions; and the non-toxicity of reagents are known as some unique features of the electrochemical protocols for the synthesis of organic compounds. In recent years, organometallic electrochemical reactions have aided the formation of one of the most important bonds in the synthesis of new molecules. Some of the most famous of these protocols are the metal-catalyzed or metal-mediated electrochemical Barbier, Nozaki–Hiyama–Kishi, Reformatsky, and Barbier–Grignard-type reactions. This review offers an overview of the application of strategies and methodologies based on electrochemical methods and metal catalysts for the allylation and alkylation of chemical compounds.