A proton magnetic resonance nuclear Overhauser enhancement study. Application to vitamin D derivatives D2 and D3

1980 ◽  
Vol 58 (12) ◽  
pp. 1206-1210 ◽  
Author(s):  
George Kotovych ◽  
Gerdy H. M. Aarts ◽  
Klaus Bock
Keyword(s):  
Conformational Equilibrium ◽  
Nuclear Overhauser Effect ◽  
Coupling Constants ◽  
Nuclear Overhauser Enhancement ◽  
Conformational Interconversion ◽  
Overhauser Effect ◽  
Effect Difference ◽  
Nuclear Overhauser ◽  
Unambiguous Assignment ◽  
Study Application

Nuclear Overhauser effect difference experiments on vitamins D2 and D3 at 400 MHz allow an unambiguous assignment to be made for the HE and HZ protons bonded to the C-19 carbon. This assignment is especially important since the A ring, and hence the C-19 atom, undergoes a conformational interconversion. The results indicate the importance of proton nOe difference experiments in determining points of configuration and they indicate that the assignment of resonances based on allylic coupling constants in a molecule undergoing a conformational equilibrium can be incorrect.

A nuclear Overhauser effect difference study of the solution conformation of (6R)-prostaglandin I1

1980 ◽  
Vol 58 (23) ◽  
pp. 2649-2659 ◽  
Author(s):  
George Kotovych ◽  
Gerdy H. M. Aarts
Keyword(s):  
Proton Magnetic Resonance ◽  
Nuclear Overhauser Effect ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Solution Conformation ◽  
Magnetic Resonance Studies ◽  
Overhauser Effect ◽  
Complete Assignment ◽  
Effect Difference ◽  
Nuclear Overhauser

Proton magnetic resonance studies at 400 MHz allowed the complete assignment of the spectra for (6R)-prostaglandin I1 in phosphate buffer and in CDCl3 solutions. The spectral analysis was based on the nuclear Overhauser effect difference measurements, which also provide accurate chemical shifts and coupling constants. Conformational differences in the two solvents for the ring portion of the molecule are indicated.

A nuclear Overhauser effect difference study and a two-dimensional J proton magnetic resonance study of (6S)-prostaglandin I1

1981 ◽  
Vol 59 (10) ◽  
pp. 1449-1454 ◽  
Author(s):  
George Kotovych ◽  
Gerdy H. M. Aarts ◽  
Tom T. Nakashima
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Nuclear Overhauser Effect ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Two Dimensional ◽  
Overhauser Effect ◽  
Effect Difference ◽  
Proton Resonances ◽  
Nuclear Overhauser

High-field nuclear Overhauser effect difference measurements allowed the assignment of the proton resonances for (6S)-prostaglandin I1 in phosphate buffer solutions. The two-dimensional J proton magnetic resonance experiments complemented these studies, as they also allowed the structure of several multiplets to be obtained when these multiplets are hidden by nearby resonances in a normal spectrum. The chemical shifts and coupling constants are compared with the data obtained previously for (6R)-prostaglandin I1.

Relaxation pathway analysis by 1H spin-lattice relaxation and nuclear Overhauser effect difference measurements. Application to a reassignment of the 1H nmr spectrum of strychnine and to the determination of the structure and stereochemistry of some strychnine sulfonic acids

1983 ◽  
Vol 61 (8) ◽  
pp. 1749-1755 ◽  
Author(s):  
Walter J. Chazin ◽  
Lawrence D. Colebrok ◽  
John T. Edward
Keyword(s):  
Pathway Analysis ◽  
Nuclear Overhauser Effect ◽  
Lattice Relaxation ◽  
Coupling Constants ◽  
Spin Lattice Relaxation ◽  
Sulfonic Acids ◽  
Spin Lattice ◽  
Overhauser Effect ◽  
Effect Difference ◽  
Nuclear Overhauser

The 1H relaxation pathway analysis of strychnine and some strychnine sulfonic acids has been carried out by spin-lattice relaxation and nuclear Overhauser effect difference measurements. Some previously reported 1H chemical shifts and coupling constants for strychnine are shown to be in error. New assignments for positions 15, 17, 18, and 20 have been made. Proposed sites of substitution of the sulfonic acids have been verified, and the previously undetermined stereochemistry of one of the acids has been established.

The isolation, structure, and stereochemistry of traversiadiene. The precursor hydrocarbon of traversianal biosynthesis

1989 ◽  
Vol 67 (8) ◽  
pp. 1302-1304 ◽  
Author(s):  
Albert Stoessl ◽  
G. L. Rock ◽  
J. B. Stothers
Keyword(s):  
Magnetic Resonance ◽  
Biosynthetic Pathway ◽  
Nuclear Overhauser Effect ◽  
Difference Spectra ◽  
Heteronuclear Correlation ◽  
Magnetic Resonance Studies ◽  
Overhauser Effect ◽  
Effect Difference ◽  
Nuclear Overhauser ◽  
Magnetic Resonance Spectra

A tricyclic diene, traversiadiene, isolated from cultures of Cercosporatraversiana has been shown to have the structure and stereochemistry of the previously postulated hydrocarbon intermediate on the biosynthetic pathway to traversianal (1). Detailed:1H and 13C magnetic resonance studies, including homo- and heteronuclear correlation spectra, led to the gross structure, and the stereochemistry was established through a series of nuclear Overhauser effect difference spectra. Keywords: diterpene, traversiadiene, 1H and 13C magnetic resonance spectra.

Revised structure of a delta-aminolevulinic acid derivative

1993 ◽  
Vol 39 (9) ◽  
pp. 1867-1871 ◽  
Author(s):  
M Kajiwara ◽  
K Hara ◽  
K Takatori ◽  
K Matsumoto
Keyword(s):  
Aminolevulinic Acid ◽  
Nuclear Overhauser Effect ◽  
Correlation Spectroscopy ◽  
Molecular Formula ◽  
X Ray ◽  
Overhauser Effect ◽  
13C Nuclear Magnetic Resonance ◽  
Relative Arrangement ◽  
Effect Difference ◽  
Nuclear Overhauser

Abstract The structure of the fluorescent derivative formed in the method of Okayama et al. (Clin Chem 1990; 36:1494-7) for determining delta-aminolevulinic acid (ALA) concentrations was reinvestigated after esterification. The molecular ion peak at m/z 303.1473 corresponded to the molecular formula of C17H21NO4 (calcd 303.1470). The infrared spectrum showed the presence of carbonyl and carboxyl groups. This compound contained two acetyl groups, two methyl groups, and one methoxycarbonylethyl group, as revealed by 1H and 13C nuclear magnetic resonance and 13C-1H shift-correlated spectroscopy. Experiments with correlation spectroscopy via long-range coupling indicated that the main skeleton is 3H-pyrrolizine. The relative arrangement of functional groups was determined by means of nuclear Overhauser effect difference experiments. We were led to the conclusion that the methyl ester of the derivative is 2,6-diacetyl-1,5-dimethyl-7-(2-methoxycarbonylethyl)-3H-pyrrolizine. This structure was unequivocally confirmed by x-ray analysis; therefore, the structure of the derivative itself is 2,6-diacetyl-1,5-dimethyl-7-(2-carboxyethyl)-3H-pyrrolizine.

Beiträge zur Chemie des Silieiums und Germaniums, XXIX [1] 29Si-NMR-spektroskopische Untersuchungen von geradkettigen und verzweigten Silanen / Contributions to the Chemistry of Silicon and Germanium, XXIX [1] 29Si NMR Spectroscopic Investigations on Straight and Branched Silanes

1980 ◽  
Vol 35 (3) ◽  
pp. 282-296 ◽  
Author(s):  
Josef Hahn
Keyword(s):  
Nuclear Overhauser Effect ◽  
Empirical Relationship ◽  
Spin Systems ◽  
Coupling Constants ◽  
Complete Analysis ◽  
29Si Nmr ◽  
Overhauser Effect ◽  
Coupling Parameters ◽  
Nuclear Overhauser ◽  
Silicon And Germanium

,The structure of the straight silanes SinH2n+2 (1 ≤ n ≤ 7) and of the branched isomers isotetrasilane, iso- and neopentasilane, 2-silyl- and 3-silylpentasilane, 2,3-disilyltetrasilane as well as 2-silyl- and 3-silylhexasilane could be unambiguously elucidated by 29Si NMR spectroscopy. Systematic trends in the chemical shift and coupling parameters were observed and an empirical relationship between δ(29Si) of a 29Si nucleus and the number of the neighbouring silicon atoms in αβor γposition is given. In 1H decoupled spectra the nuclear Overhauser effect on the 29Si resonance was found to increase with increasing distance of the 29Si nucleus from the end of the chain. A complete analysis of the multi spin systems of disilane, trisilane and isotetrasilane was performed and the signs of the 29Si,H- and H,H-long range coupling constants were determined with regard to the negative sign of 1J(29SiH).

Determination of configuration and conformation of isoxazolidines by nuclear Overhauser effect difference spectroscopy

1982 ◽  
Vol 47 (23) ◽  
pp. 4397-4403 ◽  
Author(s):  
Philip DeShong ◽  
C. Michael Dicken ◽  
Ronald R. Staib ◽  
Alan J. Freyer ◽  
Steven M. Weinreb
Keyword(s):  
Nuclear Overhauser Effect ◽  
Difference Spectroscopy ◽  
Overhauser Effect ◽  
Effect Difference ◽  
Nuclear Overhauser ◽  
Configuration And Conformation

Determination of the stereochemistry of isoxazolidinium salts by nuclear Overhauser effect difference spectroscopy

1988 ◽  
Vol 26 (11) ◽  
pp. 974-979 ◽  
Author(s):  
A. Liguori ◽  
R. Ottanà ◽  
G. Romeo ◽  
E. Rotondo ◽  
G. Sindona ◽  
...  
Keyword(s):  
Nuclear Overhauser Effect ◽  
Difference Spectroscopy ◽  
Overhauser Effect ◽  
Effect Difference ◽  
Nuclear Overhauser
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