Configurational assignment of epimeric secondary six-membered allylic alcohols by 13C nuclear magnetic resonance spectroscopy. A new approach

1986 ◽  
Vol 64 (12) ◽  
pp. 2331-2333 ◽  
Author(s):  
Teodoro S. Kaufman ◽  
Mirta P. Mischne ◽  
Manuel Gonzalez-Sierra ◽  
Edmundo A. Ruveda
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Hydroxyl Group ◽  
Allylic Alcohols ◽  
Resonance Spectroscopy ◽  
New Approach ◽  
Configurational Assignment ◽  
13C Nuclear Magnetic Resonance ◽  
Nuclear Magnetic

On the basis of the effects of the hydroxyl group on the 13C nuclear magnetic resonance chemical shifts of the olefinic carbons, a new parameter was defined and a new rule was proposed for the assignment of the stereochemistry of secondary six-membered cyclic allylic alcohols.

Configurationally dependent hydroxyl group effects on 13C nuclear magnetic resonance chemical shifts of olefinic carbons in cyclic six-membered allylic alcohols

1988 ◽  
Vol 66 (12) ◽  
pp. 3128-3131 ◽  
Author(s):  
Teodoro S. Kaufman
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Hydroxyl Group ◽  
Allylic Alcohols ◽  
Stereochemical Assignment ◽  
13C Nuclear Magnetic Resonance ◽  
Group Effects ◽  
Nuclear Magnetic

The differences in chemical shifts of olefinic carbons, Δδ(sp2), of pseudoequatorial and pseudoaxial six-membered allylic alcohols were correlated with the Δδ(sp2) values of their parent olefins. The results obtained reflect configurationally dependent substituent effects, the magnitude of which could be used for the stereochemical assignment of the hydroxyl group in these compounds.

The characterization of primary, secondary, and tertiary vanadate alkyl esters by 51V nuclear magnetic resonance spectroscopy

1988 ◽  
Vol 66 (10) ◽  
pp. 2570-2574 ◽  
Author(s):  
Alan S. Tracey ◽  
Michael J. Gresser
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Magnetic Resonance Spectroscopy ◽  
Nuclear Magnetic Resonance Spectroscopy ◽  
Chemical Shifts ◽  
Hydroxyl Group ◽  
Resonance Spectroscopy ◽  
Low Field ◽  
Nuclear Magnetic

A variety of alkyl vanadates has been studied by 51V nuclear magnetic resonance spectroscopy. It was found that the equilibrium constant for condensation of vanadate with alcohols is insensitive to whether the hydroxyl group is primary, secondary, or tertiary. These products, however, have characteristic vanadium chemical shifts that allow assignment of nmr signals to the appropriate ester. It was also found that chemical shifts are additive in the sense that the chemical shifts of the esters ROVO3H− are one half the chemical shift of the diesters (RO)2VO2− when those shifts are given relative to −559 ppm. This effect is independent of whether the signals are to high or low field of −559 ppm and the additivity extends to mixed ligand systems. This value of −559 ppm is close but not equal to the chemical shift of the vanadate monoanion, H2VO41−, which is at −561 ppm. These results are at variance with arguments concerning the effects of ligand bulkiness on chemical shifts of vanadium(V) complexes.

Application of 13C nuclear magnetic resonance to the conformational analysis of vicinally di- and trisubstituted cyclohexanes: halohydrins, methoxyhalohydrins, and their acetates

1985 ◽  
Vol 63 (8) ◽  
pp. 2143-2148 ◽  
Author(s):  
G. W. Buchanan ◽  
J. W. Bovenkamp ◽  
A. Rodrigue ◽  
R. A. B. Bannard ◽  
R. Y. Moir
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Low Temperature ◽  
Chemical Shifts ◽  
Resonance Spectroscopy ◽  
Free Energies ◽  
Relative Peak Area ◽  
13C Nuclear Magnetic Resonance ◽  
Conformational Equilibria ◽  
Nuclear Magnetic

Low temperature 13C nuclear magnetic resonance spectroscopy has been employed to obtain the chemical shifts and to examine the conformational equilibria of the four chlorohydrins and bromohydrins of 3-methoxycyclohexene. The corresponding acetates and the unsubstituted halohydrins have also been examined. The observed chemical shifts were compared with those calculated from additivity considerations. Limitations of this approach are discussed. Relative peak area measurements have been used to obtain conformational free energies in favourable cases.

Identification of C-24 alkyl epimers of marine sterols by 13C nuclear magnetic resonance spectroscopy

1978 ◽  
Vol 56 (14) ◽  
pp. 1898-1903 ◽  
Author(s):  
J. L. C. Sright ◽  
A. G. McInnes ◽  
S. Shimizu ◽  
D. G. Smith ◽  
J. A. Walter ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Structural Changes ◽  
Chemical Shifts ◽  
Resonance Spectroscopy ◽  
H Nmr ◽  
Nuclear Magnetic Resonance Spectra ◽  
13C Nuclear Magnetic Resonance ◽  
Nuclear Magnetic

13C nuclear magnetic resonance spectra of diastereomeric C-24 alkyl sterols have been assigned. Differences in the chemical shifts of side-chain carbons permitted the determination of the absolute configuration at C-24 in several sterols since these chemical shifts are insensitive to structural changes remote from the asymmetric centre. An unknown sterol from Tetraselmissuecica has been identified as (24R)-24-methylcholest-5-en-3β-ol and the configuration assigned from 1H nmr data to the sterol from Phaeodoctylumtricornutum has been confirmed. The utility and potential of this method in characterising new sterols and their biological precursors is discussed.

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.

Imaging of 13C-labeled glucose and sorbitol in bovine lens by 1H-detected 13C nuclear magnetic resonance spectroscopy

2003 ◽  
Vol 21 (9) ◽  
pp. 1029-1031 ◽  
Author(s):  
Tomoko Sawada ◽  
Jiro Nakamura ◽  
Yasuhiro Nishida ◽  
Kazutaka Kani ◽  
Ryohei Okamoto ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Nuclear Magnetic Resonance Spectroscopy ◽  
Resonance Spectroscopy ◽  
Bovine Lens ◽  
13C Nuclear Magnetic Resonance ◽  
Nuclear Magnetic
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