Plasma Electrochemistry for Carbon–Carbon Bond Formation via Pinacol Coupling
Jian Wang, Necip B. Üner, Scott E. Dubowsky, Matthew P. Confer, Rohit Bhargava, Yunyan Sun, Yuting Zhou, R. Mohan Sankaran, Jeffrey S. Moore
Abstract
The formation of carbon-carbon bonds by pinacol coupling of aldehydes and ketones requires a large negative reduction potential, often realized with a stoichiometric reducing reagent. Here, we use solvated electrons generated via a plasma-liquid process. Parametric studies with methyl-4-formylbenzoate reveal that selectivity over the competing reduction to the alcohol requires careful control over mass transport. The generality is demonstrated with benzaldehydes, benzyl ketones, and furfural. A reaction-diffusion model explains the observed kinetics, and ab initio calculations provide insight into the mechanism. This study opens the possibility of a metal-free, electrically-powered, sustainable method for reductive organic reactions.