TEFDDOLs (α,α,α′,α′-Tetrakis(perfluoroaryl/alkyl)-2,2′-dimethyl-1,3-dioxolane-4,5-dimethanols): Highly Fluorinated Chiral H-Bond Donors and Bronsted Acids with Distinct H-Bonding Patterns and Supramolecular Architectures

The synthesis of six enantiopure alpha,alpha,alpha',alpha'-tetrakis(perfluoroalkyl/aryl)-2,2' -dimethyl-1,3-dioxolane-4,5-dimethanols (TEFDDOLs), by addition of perfluorinated organolithium reagents or Ruppert's reagent (TMS-CF3) 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-CF3, 5.7; tetrakis-C2F5, 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.