title: Competition of ester, amide, ether, carbonate, alcohol and epoxide ligands in the dirhodium experiment (chiral discrimination by NMR spectroscopy).
abstract: Thirty-eight derivatives of 3-hydroxy-2-methylpropanoic acid, each with two different oxygen functionalities, were synthesized and subjected to the standard dirhodium experiment (1H NMR in the presence of an equimolar amount of the chiral dirhodium tetracarboxylate complex Rh*). Their structures represent ester, amide, carbonate, ether, alcohol and/or epoxy groups. Significant selectivity in the binding of those oxygen groups to the complex were determined. From these results, a priority list in binding to a rhodium atom of Rh* was established: epoxides > primary alcohols > ethers > or = esters > or = amides > carbonates > tertiary alcohols. This sequence allows the prediction of the preferred binding site of oxygen-containing groups in polyfunctional compounds, which frequently occur among natural products, and, particularly, in asymmetric synthesis of such compounds. Differentiation of the enantiomers by the dirhodium experiment is easily accomplished due to numerous signal dispersions in nearly all cases.
authors.affiliation: Leibniz University Hannover, Institute of Organic Chemistry, Schneiderberg 1B, D-30167 Hannover, Germany.
authors.forename: Jens T
authors.initials: JT
authors.lastname: Mattiza
authors.forename: Vera
authors.initials: V
authors.lastname: Meyer
authors.forename: Gülsüm
authors.initials: G
authors.lastname: Ozüduru
authors.forename: Tanja
authors.initials: T
authors.lastname: Heine
authors.forename: Joerg
authors.initials: J
authors.lastname: Fohrer
authors.forename: Helmut
authors.initials: H
authors.lastname: Duddeck
mesh_terms: D001667:Binding, Competitive; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D009942:Organometallic Compounds / Q000737:chemistry*; D011422:Propionates / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D008024:Ligands; D009942:Organometallic Compounds; D011422:Propionates; C519986:dirhodium tetracarboxylate