1H and13C NMR study of the effects exerted by an oxirane ring in the epoxybicyclo-[2.2.2]octane series

Autor: F. Plénat, Colette Laffite, G. Renard, H. Christol
Rok vydání: 1981
Předmět:
Zdroj: Organic Magnetic Resonance. 17:110-117
ISSN: 1097-458X
0030-4921
DOI: 10.1002/mrc.1270170207
Popis: The 1H and 13C NMR spectra of 2,3-disubstituted exo-5,6- and endo-5,6-bicyclo[2.2.2]octanes, and the corresponding alkanes, have been investigated to determine the effects exerted by an oxirane ring. The 1H NMR study showed that the anti protons, H-7a and H-8a, are significantly shielded and the syn protons, H-7s and H-8s, are deshielded, although to a smaller extent, by the exo-oxirane. An endo-oxirane has practically no effect on the same protons. The stereochemistry of epoxybicyclo[2.2.2]octanes is, thus, easily deduced from 1H NMR data. The 13C NMR study of the epoxy compounds provided an estimate of the value of α, β, γ syn and γ anti effects (to the epoxide oxygen) of an oxirane ring. In these rigid bicyclic molecules, of known geometry, the γ syn and the γ anti effects are of the same value, even though the dihedral angles are very different (0° and 120°).
Databáze: OpenAIRE
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