Research on the design, synthesis, and catalytic activity of chiral N-heterocyclic carbene ligand-metal complexes

New chiral C-2 symmetric N-heterocyclic carbene (NHC) ligands with a binaphthyl backbone have been synthesized. X-ray crystallographic analysis of the new NHC-AuCI complex revealed that the phenyl groups of the binaphthyl backbone sterically regulated the direction of the nitrogen substituents of the imidazolylidene which would induce enantioselectivity in reactions. The new cationic NHC-Au(I) complexes efficiently catalyzed the cyclization of a 1,6-ene-yne and the intermediate of the cyclization was trapped by MeOH to afford the final product in high yields with up to 44% ee. (C) 2016 Elsevier Ltd. All rights reserved.