Nuclear magnetic resonance studies. XVIII.The proton parameters of some bicyclo[2•2•2]octane derivatives

1969 ◽  
Vol 47 (19) ◽  
pp. 3515-3528 ◽  
Author(s):  
Gurudata Gurudata ◽  
J. B. Stothers
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
High Resolution ◽  
Long Range ◽  
Coupling Constants ◽  
Magnetic Resonance Studies ◽  
Anisotropic Effect ◽  
Shielding Effects ◽  
Nuclear Magnetic

The high resolution proton spectra of ten substituted bicyclo[2•2•2]octenes and octanes have been analyzed. The proton shieldings and coupling constants are discussed with particular emphasis on the stereochemical dependence of these parameters. Evidence bearing on the anisotropic effect of carbonyl bonds is presented to substantiate other recent findings on these shielding effects. Certain long-range couplings permit stereochemical assignments.

Nuclear Magnetic Resonance Studies. XXIII. Long-range 1H–1H Couplings (JHCCOCH) in some Methyl Bicyclo[2.2.1]heptane-2-carboxylates

1971 ◽  
Vol 49 (12) ◽  
pp. 2152-2155 ◽  
Author(s):  
H. Brouwer ◽  
J. B. Stothers
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Long Range ◽  
Coupling Constants ◽  
Magnetic Resonance Studies ◽  
Nuclear Magnetic

The methoxyl proton signals of several 3-substituted 2-carbomethoxybicyclo[2.2.1]hept-5-enes and -heptanes appear as doublets because of 1H–1H coupling over five σ-bonds (5J). The dependence of these long-range coupling constants on the nature and orientation of 2- and 3- substituents is discussed in terms of the probable conformations of the 2-carbomethoxyl groups.

High-Resolutjon nuclear-magnetic-resonance spectra of hydrocarbon groupings VI. The hydrogen spectra of carbon-13 substituted ethane, ethylene and acetylene

1962 ◽  
Vol 269 (1338) ◽  
pp. 385-403 ◽  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
High Resolution ◽  
Long Range ◽  
Experimental Results ◽  
Coupling Constants ◽  
Nuclear Magnetic Resonance Spectra ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

High-resolution spectra have been obtained from the hydrogen nuclei of appropriate isotopic mixtures of ethane, ethylene and acetylene containing one or two magnetic 13 C nuclei. Analysis of these spectra has yielded the magnitudes of all but one of the possible inter - nuclear coupling constants in these molecules, including those between pairs of carbon nuclei. Where a given molecule has several coupling constants between pairs of the same type of nuclei the relative signs of these have also been determined. Discussion of the experimental results in terms of current theoretical treatments shows that in nearly all cases the contact, H 3 , term is the most important one in determining the magnitude of the coupling constants. Only in the case of the J CC and the long-range J ' CH coupling constants of acetylene does it appear to be necessary to consider appreciable contributions from other terms.

Studies of specifically fluorinated carbohydrates. Part I. Nuclear magnetic resonance studies of hexopyranosyl fluoride derivatives

1969 ◽  
Vol 47 (1) ◽  
pp. 1-17 ◽  
Author(s):  
L. D. Hall ◽  
J. F. Manville ◽  
N. S. Bhacca
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Angular Dependence ◽  
Chemical Shifts ◽  
Relative Orientation ◽  
Coupling Constants ◽  
Pyranose Ring ◽  
Spectral Parameters ◽  
Magnetic Resonance Studies ◽  
Nuclear Magnetic

A detailed study has been made of both the 1H and 19F nuclear magnetic resonance (n.m.r.) spectra of a series of hexopyranosyl fluoride derivatives. Some of the 1H spectra were measured at 220 MHz. The 1H spectral parameters define both the configuration and the conformation of each of these derivatives. Study of the 19F n.m.r. parameters revealed several stereospecific dependencies. The 19F chemical shifts depend upon, (a) the orientation of the fluorine substituent with respect to the pyranose ring and, (b) the relative orientation of other substituents attached to the ring; for acetoxy substituents, these configurational dependencies appear to be additive. The vicinal19F–1H coupling constants exhibit a marked angular dependence for which Jtrans = ca. 24 Hz whilst Jgauche = 1.0 to 1.5 Hz for [Formula: see text] and 7.5 to 12.6 Hz for [Formula: see text] The geminal19F–1H couplings depend on the orientation of the substituent at C-2; when this substituent is equatorial JF,H is ca. 53.5 Hz and when it is axial the value is ca. 49 Hz.

Studies of specifically fluorinated carbohydrates. Part II. Nuclear magnetic resonance studies of pentopyranosyl fluoride derivatives

1969 ◽  
Vol 47 (1) ◽  
pp. 19-30 ◽  
Author(s):  
L. D. Hall ◽  
J. F. Manville
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Nuclear Magnetic Resonance Spectroscopy ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Resonance Spectroscopy ◽  
Magnetic Resonance Studies ◽  
Conformational Model ◽  
Nuclear Magnetic

Detailed studies, by 1H and 19F nuclear magnetic resonance spectroscopy, of a series of fully esterified pentopyranosyl fluorides, show that all such derivatives favor that conformer in which the fluorine substituent is axially oriented. This conclusion is supported by separate considerations of the vicinal and geminal19F–1H and 1H–1H coupling constants, of the long-range (4J) 1H–1H and 19F–1H coupling constants and of the 19F chemical shifts. The limitations of the above conformational model are discussed.

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