Electrifying Redox-Neutral Palladium-Catalyzed Carbonylations: Multielectron Transfer as a Catalyst Driving Force

Palladium-catalyzed bond-forming reactions such as carbonylations offer an efficient and versatile avenue to access products from often feedstock reagents. However, the use of catalysts also comes with a cost, as their need to be regenerated after each product-forming cycle requires balancing thermal operations. The latter can lead to high barriers even with catalysts as well as restrict their application to many products. We introduce herein an alternative approach to palladium catalyst design, where instead electrochemical potential can drive catalysis by continual two-electron cycling of the metal oxidation state. The power behind these redox steps offers a route to carry out carbonylation reactions, including the catalytic synthesis of high-energy aroyl halide electrophiles, at unprecedentedly mild ambient temperature and pressure. More generally, analysis suggests this catalyst functions by a distinct multi-electron exchange pathway, where two-electron reduction enables oxidative addition and two-electron oxidation drives product elimination. The combination creates a unique platform where both these reverse operations are favored in the same system and with electrochemical potential energy as the only added energy source.