Non-Innocent Role of Sacrificial Anodes in Electrochemical Nickel-Catalyzed C(sp2)-C(sp3) Cross-Electrophile Coupling

Abstract

Sacrificial anodes composed of inexpensive metals such as Zn, Fe and Mg are widely used to support electrochemical nickel-catalyzed cross-electrophile coupling (XEC) reactions, in addition to other reductive electrochemical transformations. Such anodes are appealing because they provide a stable counter-electrode potential and typically avoid interference with the reductive chemistry. The present study outlines development of an electrochemical Ni-catalyzed XEC reaction that streamlines access to a key pharmaceutical intermediate. Metal ions derived from sacrificial anode oxidation, however, directly contribute to homocoupling and proto-dehalogenation side products that are commonly formed in chemical and electrochemical Ni-catalyzed XEC reactions. Use of a divided cell limits interference by the anode-derived metal ions and supports high product yield with negligible side product formation, introducing a strategy to overcome one of the main limitations of Ni-catalyzed XEC.