Redox-active triazolium-derived ligands in nucleophilic fe-catalysis - Reactivity profile and development of a regioselective o-allylation

Triazolium-derived N-heterocyclic carbene (aNHC) ligands, which are readily accessible by deprotonation of the corresponding triazolium salts, proved to be versatile ligands in diverse allylic substitution reactions. The corresponding triazolium salts are formed from azides and alkynes through the application of 1,3-dipolar cycloaddition and N-alkylation reactions. The unique property of these ligands is to be zwitterionic in their liberated form and to act as strong redox-active σ-donor ligands. By virtue of these qualities, these ligands enable the development of an unprecedented Fe-catalyzed regioselective aryloxylation of allylic carbonates.