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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Endocyclic Oxygen in 3-Fluorodihydro-2H-pyran-4(3H)-one That Does Not Induce the Gauche Effect

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Author(s):
Silva, Thayna F. B. [1] ; Andrade, Laize A. F. [1] ; Silla, Josue M. [1] ; Duarte, Claudimar J. [2] ; Rittner, Roberto [2] ; Freitas, Matheus P. [1]
Total Authors: 6
Affiliation:
[1] Univ Fed Lavras, Dept Chem, BR-37200000 Lavras, MG - Brazil
[2] Univ Estadual Campinas, Inst Chem, BR-13084971 Sao Paulo - Brazil
Total Affiliations: 2
Document type: Journal article
Source: Journal of Physical Chemistry A; v. 118, n. 32, p. 6266-6271, AUG 14 2014.
Web of Science Citations: 3
Abstract

2-Fluorocyclohexanone undergoes chair inversion, giving rise to axial and equatorial conformers, with the equatorial form being highly preferred in solution, for example, 87% in chloroform and 93% in methylene chloride. Modifications in the conformational preferences can modify macroscopic properties of 2-fluoro ketones. The introduction of an endocyclic oxygen in 2-fluorocyclohexanone to give 3-fluorodihydro-2H-pyran-4(3H)-one would be expected to create a gauche effect in the axial conformer along with the O-C-C-F moiety, inducing an increase of its population. However, small changes were verified in the conformational populations both in the gas phase and solution because the carbonyl group plays an important role for the hyperconjugation in the equatorial conformer, despite experiencing strong dipolar repulsion with the fluorine atom. These data were obtained theoretically and by NMR spectroscopy, while the nature of the interactions governing these conformational shifts were investigated on the basis of natural bond orbital analysis. (AU)

FAPESP's process: 11/11098-6 - Conformational analysis of some methyl esters of amino acids and their N-acetyl-derivatives.
Grantee:Claudimar Junker Duarte
Support Opportunities: Scholarships in Brazil - Doctorate
FAPESP's process: 12/03933-5 - Conformational equilibria and intramolecular interactions for a series of amino-acids: theoretical and experimental approaches
Grantee:Roberto Rittner Neto
Support Opportunities: Regular Research Grants