Solution conformations for the flexible 1-chloro-1, 1-difluoro-2-pentanol unveiled using multinuclear magnetic resonance. Issue 8 (22nd February 2018)

• Record Type: Journal Article
• Authors: Martins, Francisco A.; Zeoly, Lucas A.; Cormanich, Rodrigo A.; Freitas, Matheus P.
• Is Part Of: Tetrahedron. Volume 74:Issue 8(2018)
• Page Start: 880
• Page End: 883
• Publication Date: 2018-02-22
• Subjects: Conformation analysis -- Nuclear magnetic resonance -- Coupling constant -- Intramolecular interactions -- Solvent effect; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tet.2018.01.008
• Languages: English
• ISSNs: 0040-4020

Abstract

Abstract: The preferred conformations of a small polyfunctional molecule containing fluorine, chlorine and hydroxyl groups, the 1-chloro-1, 1-difluoro-2-pentanol (CDP ), were completely elucidated using 1 H, 13 C and 19 F NMR in three different solvents. While the Cl-C-C-O dihedral angle was asserted using coupling constant data for the diastereotopic fluorines, the Et-C-C-O torsional angle was analyzed by means of 1 H NMR spectra with selective irradiation of the diastereotopic hydrogens and fluorines. In addition, unusual couplings of the hydroxyl hydrogen with a diastereotopic hydrogen and fluorines provided information on the O-H orientation. The behavior of 1 J C, F when the solvents varied agrees with a weak F⋅⋅⋅HO intramolecular hydrogen bond. These findings were corroborated, and the governing interactions rationalized with the aid of high level CCSD(T) theoretical calculations. Noteworthy, hyperconjugation involving the electron-acceptor σ*C-Cl orbital drives the conformational equilibrium rather than the fluorine gauche effect. Graphical abstract: