Applications of the Nuclear Overhauser Effect in organic chemistry

Kennewell, P. D.

doi:10.1021/ed047p278

Cited by 22 publications

(5 citation statements)

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“…Since the isopropyl group and the methyl group are sterically close enough to inter act magnetically in the ft-isopropyl isomer (XX) but not in the isopropyl isomer (XXVIII), it was thought that the two isomers could be differentiated using nmr analysis. The ft-isomer might be expected to show a Nuclear Overhauser Effect (49,50) in the absorption of the isopropyl group if the methyl group absorption were irradiated, while the ^-isomer should not show any such effect. Unfortunately, with the instrumentation available in these laboratories, it was impossible to make such a determination when the groups involved had such close nmr absorptions.…”

Section: XLIIImentioning

confidence: 99%

Total synthesis of dl-oplopanone

Caine¹,

Tuller²

1973

J. Org. Chem.

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Section: XLIIImentioning

confidence: 99%

Total synthesis of dl-oplopanone

Caine¹,

Tuller²

1973

J. Org. Chem.

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“…Since the intramolecular nuclear Overhauser effect (NOE) was first described by Anet and Bourn (1) in 1965, it has repeatedly been shown to be an invaluable tool in the determination of both the structure and conformation of organic compounds (2). The NOE enhancement is the amount by which the intensity of an nmr proton signal changes when the peak of a nearby proton is irradiated.…”

Section: Of the Nuclear Overhauser Effectmentioning

confidence: 99%

“…In spite of the considerable number of papers which have appeared in the last decade describing the results of NOE experiments, relatively few seem to give a detailed description of the experimental procedure involved (3). This paper will discuss procedures that were used to obtain experimental NOE enhancements on a commercial student spectrometer.2 Applications of NOE results have been reviewed by Kennewell (2).…”

Section: Of the Nuclear Overhauser Effectmentioning

confidence: 99%

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Experimental determination of the nuclear Overhauser effect

Antwerp¹

1973

J. Chem. Educ.

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“…This method allows for the estimate of spatial proximity of atomic groups within the distance interval of 2.3-3.2 A (4)(5)(6)(7)(8). In general, in order to observe a nOe between two protons, their mutual relaxation is a sufficient condition.…”

Section: Introductionmentioning

confidence: 99%

A stereodynamic investigation of antivitamins K in the dicoumarol series. II. Differentiation between the two hydroxyl groups by the nuclear Overhauser effect

Laruelle¹,

Godfroid²

1976

Can. J. Chem.

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. Can. J . Chem. 54, 813 (1976). Dicoumarol derivatives, substituted at the bridgehead, show a double restricted rotation. This hindered rotation is manifest through the appearance of two signals, the hydroxyl protons being diastereotopic at low temperatures.In this work we assign the two respective signals by the nuclear Overhauser effect. The highfield signal corresponds to a hydroxyl site close to the bridgehead tertiary proton, while the other corresponds to a site in proximity to the substituent R. The case of structurally analogous dimethones has been investigated by the same technique with identical conclusions. This disproves the interpretation made previously on the basis of steric and anisotropic effects.The interatomic distances concerned have been calculated, and these have yielded an estimate of deformations induced by the bridgehead substituents.Evidence is supplied for the different behavior of the two sites and this study gives evidence for a very facile intermolecular chemical exchange of the hydroxyl site close to the tertiary bridgehead proton in the presence of traces of protonated compounds.The overall behavior is the result of the asymmetry of the molecules of this series in their chelated form.CLAUDE LARUELLE ET JEAN-JACQUES GODFROID. Can. J. Chem. 54, 813 (1976).Les derives du dicoumarol, substitues au niveau du pont presentent une double rotation restreinte qui se manifeste par I'apparition de deux signaux, les protons hydroxyles etant diastereotropiques a basse temperature.La presente publication permet d'attribuer, par effet Overhauser nucleaire, les deux signaux aux groupes hydroxyles incrimines. Le signal a haut champ correspond au site hydroxyle proche du proton tertiaire du pont, alors que I'autre correspond au site proche du substituant R. D'autre part, le cas des dimethones, analogues structuraux, a ete etudie par la meme technique et ies conclusions sont identiques, ce qui annule l'interpretation inverse qui a ete faite anterieurement a partir d'interpretations steriques et anisotropiques. Les distances interatomiques concernees ont ete calculCeset les deformations induites par les substituants du pont estimees.Le comportement differencie des deux sites est mis en evidence et I'etude conclut a un echange chimique intermoleculaire tres facile du site hydroxyle proche du proton tertiaire du pont avec des traces d e composes protones.L'ensemble des proprietes mises en evidence est la consequence de I'asymetrie des molecules de cette serie dans leur forme chelatee.

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Applications of the Nuclear Overhauser Effect in organic chemistry

Abstract: The purpose of this paper is to show how the Nuclear Overhauser Effect (NOE) can be sued to determine the configurations and conformations of organic molecules.

Cited by 22 publications

References 10 publications

Total synthesis of dl-oplopanone

Total synthesis of dl-oplopanone

Experimental determination of the nuclear Overhauser effect

A stereodynamic investigation of antivitamins K in the dicoumarol series. II. Differentiation between the two hydroxyl groups by the nuclear Overhauser effect

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