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

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-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 (pKa 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–Faryl 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.