Solution conformations for the flexible 1-chloro-1,1-difluoro-2-pentanol unveiled using multinuclear magnetic resonance

Author(s)

Martins, Francisco A. ^[1] ; Zeoly, Lucas A. ^[2] ; Cormanich, Rodrigo A. ^[2] ; Freitas, Matheus P. ^[1]

Affiliation

^[1] Univ Fed Lavras, Dept Chem, BR-37200000 Lavras, MG - Brazil

^[2] Univ Estadual Campinas, Inst Chem, BR-13083970 Campinas, SP - Brazil

• Document type: Journal article
• Source: Tetrahedron; v. 74, n. 8, p. 880-883, FEB 22 2018.
• Web of Science Citations: 2

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 H-1, C-13 and F-19 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 H-1 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 center dot center dot center dot 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 sigma{*}(C-Cl) orbital drives the conformational equilibrium rather than the fluorine gauche effect. (C) 2018 Elsevier Ltd. All rights reserved. (AU)

• FAPESP's process: 17/02364-0 - Mechanistic investigations of the biginelli reaction using experimental and theoretical approaches
• Grantee: Rodrigo Antonio Cormanich
• Support Opportunities: Scholarships abroad - Research