Historical and recent advances in enantioselective NHC-catalyzed radical reactions

Abstract

The transition of N-heterocyclic carbene (NHC)-catalyzed reactions from conventional two-electron pathways to single-electron transfer (SET) mechanisms has significantly broadened the scope and versatility of NHC catalysis in organic synthesis. This paradigm shift began with the confirmation of SET processes and has since enabled the development of enantioselective radical transformations, facilitating the construction of complex molecular architectures previously challenging to access using NHCs. Recent advancements, such as Cramer’s work on tunable chiral NHCs for α-functionalization, exemplify the growing sophistication of selective NHC-catalyzed radical chemistry. Herein, we present a systematic overview of these developments, detailing the evolution of NHC-mediated SET processes and their potential for the efficient synthesis of structurally intricate molecules with high enantiomeric purity. By highlighting these historical efforts, we aim to provide valuable insights for both experienced researchers and newcomers to the field.