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.

The Catalytic Effect of Fluoroalcohol Mixtures Depends on Domain Formation

“…TEFDDOLs 15 are highly fluorinated analogues of the tartrate-derived TADDOLs. 16 TEFDDOLs such as compound 1 (Figure 6) harbor, in an intramolecular fashion, highly polar hydroxyl groups, the fluorinated substituents (here CF 3 ) at the tertiary alcohol functionality, and nonpolar alkyl residues at the acetal carbon (here CH 3 ).…”

“…Segregation of polar (hydroxyl groups, red), nonpolar (the CH 3 units and the rings, gray) and fluorous (CF 3 −C-CF 3 units, green) phases in the crystal structure of 1 (cf. the liquid structure of system V in Figure4, for the Lewis structure see Figure6) 15.…”

Cationic Chiral Fluorinated Oxazaborolidines. More Potent, Second-Generation Catalysts for Highly Enantioselective Cycloaddition Reactions

“…Hydrogenation and exhaustive pentafluoroethylation of the esters in adduct 31 afforded the intriguing diol 32 . Tartaric acid-derived perfluorodiols similar to 32 have been shown by Berkessel to be highly acidic with p K a values as low as 2.4 in DMSO, and diols based on bicyclo[2.2.1]­heptanes have been successfully applied to enantioselective catalysis . The strongly electron-withdrawing effect exerted by the perfluoroalkyl substituents also leads to a large enhancement of acidity of the phosphoric acid diester 34 as estimated from relative rates of intramolecular Prins cyclization in comparison with standards of known p K a (see Supporting Information for details).…”

Asimetrik Hetero Diels-Alder Reaksiyonu için Organaokatalizör Olarak Kiral 1,4-Hidroksiarilalkoller (HAROL) ve 1,4-Aminoalkilfenoller (AAP)

“…Diols (4), e.g. TADDOL, BINOL, and their derivatives, generally are capable of forming one intramolecular and one intermolecular hydrogen bond, while (thio)ureas (1 and 2) and squaramides (3) are characteristically able to donate two H-bonds to an acceptor [5][6][7]. In 2003, Rawal and co-workers achieved enantioselective HDA reaction between aldehydes (9) and Rawal's diene (8) by using TADDOLs (α,α,α′,α′-tetraaryl-2,2dimethyl-1,3-dioxolane-4,5-dimethanol, a diol) as the HBD organocatalysts [8].…”