Promotion of Appel-Type Reactions by N-Heterocyclic Carbenes
N-Heterocyclic carbenes (NHCs) have been used extensively as a versatile class of catalysts and ligands in organocatalytic and organometallic chemistry. However, there are only a small number of synthetic applications where they act as reagents. Here we demonstrate that NHCs can be used as stoichiometric redox reagents for Appel-type halogenation reactions of alcohols. This new reactivity reveals a fresh and interesting aspect and enriches chemistry of NHCs in an underexplored area. The potential of performing this chemical transformation at catalytic level using an NHC-oxide derivative is also investigated.