title: Asymmetric catalysis with substitutionally labile yet stereochemically stable chiral-at-metal iridium(III) complex.
abstract: A metal-coordination-based high performance asymmetric catalyst utilizing metal centrochirality as the sole element of chirality is reported. The introduced substitutionally labile chiral-at-metal octahedral iridium(III) complex exclusively bears achiral ligands and effectively catalyzes the enantioselective Friedel-Crafts addition of indoles to α,β-unsaturated 2-acyl imidazoles (19 examples) with high yields (75%-99%) and high enantioselectivities (90-98% ee) at low catalyst loadings (0.25-2 mol %). Counterintuitively, despite its substitutional lability, which is mechanistically required for coordination to the 2-acyl imidazole substrate, the metal-centered chirality is maintained throughout the catalysis. This novel class of reactive chiral-at-metal complexes will likely be of high value for a large variety of asymmetric transformations.
authors.affiliation: Fachbereich Chemie, Philipps-Universität Marburg , Hans-Meerwein-Strasse, 35043 Marburg, Germany.
authors.forename: Haohua
authors.initials: H
authors.lastname: Huo
authors.forename: Chen
authors.initials: C
authors.lastname: Fu
authors.forename: Klaus
authors.initials: K
authors.lastname: Harms
authors.forename: Eric
authors.initials: E
authors.lastname: Meggers