Assessment of the Reducibility of Breslow Enolates Derived From Mesoionic Carbenes

ABSTRACT Mesoionic carbenes (MICs) exhibit stronger σ‐donating and weaker π‐accepting properties compared to classical N ‐heterocyclic carbenes (NHCs), positioning their Breslow enolates as super electron donors for single‐electron transfer (SET) processes. This work evaluates the reducibility of Breslow enolates (BI−s) derived from MICs by synthesizing a series of 4‐acyl‐1,2,3‐triazoliums with diverse substituents and analyzing their electrochemical properties via cyclic voltammetry. Substituents exerted significant influence on reduction potentials, with electron‐donating groups lowering potentials and electron‐withdrawing groups elevating them. Substituent position further modulated reducibility, as electron‐withdrawing esters increased potential by reducing electron density. Alkali metal cations (Li⁺, Na⁺, K⁺) can also alter the redox potential and reversibility. The electrochemical data provide a foundation for designing MIC‐catalyzed SET reactions, expanding synthetic applications in radical‐mediated transformations and photocatalysis. This work bridges gaps in understanding MIC redox behavior, enabling targeted reaction design for diverse carbon–carbon bond‐forming processes.