Light-Promoted Organocatalysis with N-Heterocyclic Carbenes

Abstract

The combination of N-heterocyclic carbene (NHC)-organocatalysis with photochemical activation can lead to unprecedented reaction pathways not observed without light. A selection of dual catalytic systems merging NHCs with photoredox catalysis, for example, have leveraged the ability of NHCs to stabilize intermediate radical species and facilitate single electron transfer events. Furthermore, NHCs can transiently modulate the photochemical properties of a substrate and enable direct absorption of otherwise photoinactive organic compounds. In this Concept article, the recent advances in this rapidly developing field are summarized. For each transformation, a particular focus is placed on the mechanistic aspects of the process while key features that highlight the synthetic potential of the light mediated NHC organocatalysis are presented.