Novel N-heterocyclic carbene ligand precursors, N-heterocyclic carbene ligands and N-heterocyclic metal-carbene complexes are provided. Metal-carbene complexes comprising N-heterocyclic carbene ligands can be chiral, which are useful for catalyzing enantioselective synthesis. Methods for the preparation of the N-heterocyclic carbene ligands and N-heterocyclic metal-carbene complexes are given.
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