N-heterocyclic carbenes (NHCs) serve as highly proficient ligands in many transition metal catalyzed reactions. As such, significant efforts have been devoted to the extension of NHCs into the field of asymmetric catalysis. Development was slow at first but is now rapidly accelerating, evidenced by the increase in number of transformations displaying excellent enantioselectivities. Chronicled here are the attempts at asymmetric catalysis with NHC ligands, and the results are categorized by the metal effecting catalysis as well as the type of reaction. Ruthenium, rhodium, iridium, palladium, and copper complexed with NHCs have all demonstrated excellent enantioselectivities in catalysis, and fundamental reactions such as olefin metathesis, alkene hydrogenation, kinetic resolution of secondary alcohols, and conjugate addition have been carried out with high selectivity.
Keywords: Chiral, Diaminocarbene-Metal, Asymmetric, Catalysis, N-heterocyclic carbenes (NHCs), ligands, transition metal, olefin metathesis