title: Progress of Chiral Schiff Bases with C1Symmetry in Metal-Catalyzed Asymmetric Reactions.
abstract: In this Personal Account, various chiral Schiff base-metal-catalyzed enantioselective organic reactions are reported; the Schiff bases used were O,N,O- as well as N,N,P-tridentate ligands and N,N-bidentate ligands having C1symmetry. In particular, the enantioselective addition of trimethylsilyl cyanide, dialkylzinc, and organozinc halides to aldehydes, enantioselective 1,4-addition of dialkylzinc to cyclic and acyclic enones, and asymmetric allylic oxidation are reported. Typically, ketimine-type Schiff base-metal complexes exhibited higher reactivity and enantioselectivity compared with the corresponding aldimine-type Schiff base-metal complexes. Notably, remarkable ligand acceleration was observed for all reactions. The obtained products can be used as key intermediates for optically active natural products and pharmaceuticals.
authors.affiliation: Department of Chemistry Graduate School of Science, Kobe University, Nada, Kobe 657-8501, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Hayashi
keywords: Schiff bases; asymmetric catalysis; enantioselectivity; ligand design; tridentate ligands