Electrolyte Induced Solvent Cage Effects for Enantioselective Electrosynthesis

Abstract

Electrochemistry provides a tunable, regioselective, and green alternative to traditional synthetic organic methods, and access to reactive intermediates. Problematically, electrochemical redox events often go through planar radical intermediates, thus destroying enantioselectivity. As such, researchers have sought the “chiral electron”, a general methodology to impart enantioselectivity to electroorganic reactions. One strategy has been asymmetric transition metal catalysis while replacing the typical stochiometric redox reagent needed with electricity, thus providing a chiral pathway for elecoorganic reactions. However, the general physical parameters that govern enantioselectivity at electrochemical interfaces, remains poorly understood.Here, we focus on the effects of supporting electrolyte in synthetic organic electrochemistry, specifically its role in enantioselective reactions. Cyclic voltammetry provides a tool to investigate the mechanistic consequences of changes in electrolyte. Using the model reaction of enantioselective carboxylation with a cobalt catalyst, we observe changes in mechanism as the electrolyte size is varied. Specifically, electrolyte identity effects the lifetime of the chiral Co-alkyl intermediate. These fundamental electroanalytical studies provide a sound mechanistic basis for the origin of enantioselectivity in electroorganic reactions. In summary, these results of a general interest as a strategy to tune and improve enantioselectivity in electrochemical transformations.