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

Autor(es)

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]

Afiliação do(s) autor(es)

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

^[2] Univ Estadual Campinas, Inst Chem, BR-13084971 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Journal of Physical Chemistry A; v. 118, n. 32, p. 6266-6271, AUG 14 2014.
• Citações Web of Science: 3

Resumo

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)

• Processo FAPESP: 11/11098-6 - Análise conformacional de alguns ésteres metílicos de aminoácidos e seus N-acetil-derivados.
• Beneficiário: Claudimar Junker Duarte
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 12/03933-5 - Equilíbrios conformacionais e interações intramoleculares em uma série de aminoácidos: abordagem teórica e experimental
• Beneficiário: Roberto Rittner Neto
• Modalidade de apoio: Auxílio à Pesquisa - Regular