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

摘要

The synthesis of six enantiopure α,α,α′,α′-ntetrakis(perfluoroalkyl/aryl)-2,2′-dimethyl-1,3-dioxolane-4,5-ndimethanols (TEFDDOLs), by addition of perfluorinatednorganolithium reagents or Ruppert’s reagent (TMS-CF3) tonisopropylidene tartaric dichloride, is reported. X-ray crystalnstructures of the TEFDDOLs alone or in complexes with Hbondnacceptors such as water and DABCO revealed that thisnnew class of highly fluorinated chiral 1,4-diols forms distinctnintra- and intermolecular H-bond patterns. IntramolecularnOH−OH bonding accounts for the relatively high acidity ofnthe perfluoroalkyl TEFDDOLs (pKa in DMSO: tetrakis-CF3, 5.7; tetrakis-C2F5, 2.4). For the tetrakis(perfluorophenyl)nTEFDDOL, a quite unusual “pseudo-anti” conformation of the diol, with no intramolecular (and no intermolecular) OH−OHnbonds, was found both in the crystal and in solution (DOSY and NOESY NMR). The latter conformation results from a total ofnfour intramolecular OH−Faryl hydrogen bonds overriding OH−OH bonding. Due to their H-bonding properties, thenTEFDDOLs are promising new building blocks for supramolecular and potentially catalytic applications.