Disclosing Cyclic(Alkyl)(Amino)Carbenes as a One-Electron Reductant: Synthesis of Acyclic(Amino)(Aryl)Carbene-Based Kekulé Diradicaloids

Herein we disclose cyclic(alkyl)(amino)carbenes (CAACs) as a one-electron reductant under the formation of a transient radical cation as indicated by EPR spectroscopy. Subsequently, the disclosed CAAC reducing reactivity was utilized for the synthesis of acyclic(amino)(aryl)carbene-based Thiele and Chichibabin hydrocarbons, a new class of Kekulé diradicaloids. The results demonstrate the CAAC to be a potent organic reductant. Notably, the acyclic(amino)(aryl)carbene-based Chichibabin's hydrocarbon shows an appreciable population of the triplet state at room temperature, as evidenced by both variable temperature NMR and EPR spectroscopy.