Non-Innocent Role of Sacrificial Anodes in Electrochemical Nickel-Catalyzed C(sp <sup>2</sup> )–C(sp <sup>3</sup> ) Cross-Electrophile Coupling
Luana Cardinale, Gregory L. Beutner, Christopher Y. Bemis, Daniel J. Weix, Shannon S. Stahl
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 the 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 a high product yield with negligible side product formation, introducing a strategy to overcome one of the main limitations of Ni-catalyzed XEC.