title: TEFDDOLs (α,α,α',α'-tetrakis(perfluoroaryl/alkyl)-2,2'-dimethyl-1,3-dioxolane-4,5-dimethanols): highly fluorinated chiral H-bond donors and Brønsted acids with distinct H-bonding patterns and supramolecular architectures.
abstract: The synthesis of six enantiopure α,α,α',α'-tetrakis(perfluoroalkyl/aryl)-2,2'-dimethyl-1,3-dioxolane-4,5-dimethanols (TEFDDOLs), by addition of perfluorinated organolithium reagents or Ruppert's reagent (TMS-CF(3)) to isopropylidene tartaric dichloride, is reported. X-ray crystal structures of the TEFDDOLs alone or in complexes with H-bond acceptors such as water and DABCO revealed that this new class of highly fluorinated chiral 1,4-diols forms distinct intra- and intermolecular H-bond patterns. Intramolecular OH-OH bonding accounts for the relatively high acidity of the perfluoroalkyl TEFDDOLs (pK(a) in DMSO: tetrakis-CF(3), 5.7; tetrakis-C(2)F(5), 2.4). For the tetrakis(perfluorophenyl) TEFDDOL, a quite unusual "pseudo-anti" conformation of the diol, with no intramolecular (and no intermolecular) OH-OH bonds, was found both in the crystal and in solution (DOSY and NOESY NMR). The latter conformation results from a total of four intramolecular OH-F(aryl) hydrogen bonds overriding OH-OH bonding. Due to their H-bonding properties, the TEFDDOLs are promising new building blocks for supramolecular and potentially catalytic applications.
authors.affiliation: Department of Chemistry (Organic Chemistry), University of Cologne, Greinstraße 4, 50939 Cologne, Germany. berkessel@uni-koeln.de
authors.forename: Albrecht
authors.initials: A
authors.lastname: Berkessel
authors.forename: Sonja S
authors.initials: SS
authors.lastname: Vormittag
authors.forename: Nils E
authors.initials: NE
authors.lastname: Schlörer
authors.forename: Jörg-M
authors.initials: JM
authors.lastname: Neudörfl