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.

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.

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.

Proton magnetic resonance spectra of catechin and bromocatechin derivatives: C6- vs. C8-substitution

1986 ◽  
Vol 64 (10) ◽  
pp. 1998-2005 ◽  
Author(s):  
E. Kiehlmann ◽  
A. S. Tracey
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Nuclear Overhauser Effect ◽  
Chemical Shifts ◽  
Overhauser Effect ◽  
Resonance Frequencies ◽  
The Difference ◽  
Nuclear Overhauser ◽  
Unambiguous Assignment ◽  
Magnetic Resonance Spectra

The 1Hmr spectra of 20 catechin derivatives substituted at C-6/C-8 by bromine and/or hydrogen and at oxygen by methyl, acetyl, and/or hydrogen have been analyzed in deuterated acetone, acetonitrile, and chloroform. Because of its dependence on the nature of the solvent and of the oxygen substituent, the difference between H-6 and H-8 chemical shifts has been found to be an unreliable criterion for the distinction between 8-bromo and 6-bromo isomers. In methylated catechins, double irradiation of H-8 and H-6 enhances one (MeO-7) and two (MeO-5 and MeO-7) methoxy signals, respectively, via the nuclear Overhauser effect. This permits unambiguous assignment of chemical shifts to all ring A protons. The H-6 and H-8 resonance frequencies of catechin have been determined by decoupling of the OH-5 and OH-7 protons.

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.

Synthesis, multinuclear NMR, and solution conformation of (η5-indenyl)CoIRfL complexes (L = CO, P-donor)

1992 ◽  
Vol 70 (10) ◽  
pp. 2544-2551 ◽  
Author(s):  
Chet R. Jablonski ◽  
Zhongxin Zhou
Keyword(s):  
Nuclear Overhauser Effect ◽  
Spectroscopic Characterization ◽  
Solution Conformation ◽  
H Nmr ◽  
Overhauser Effect ◽  
Ring Junction ◽  
Effect Difference ◽  
Perfluoroalkyl Group ◽  
Nuclear Overhauser ◽  
Indenyl Complexes

The preparation, spectroscopic characterization, and conformational analysis of a series of Co(III) indenyl complexes, (C9H7)CoIRfL (Rf = C3F7, C6F13, L = CO, P-donor), 2–8, are described. I3C and 1H NMR parameters are consistent with a slightly distorted -η5-C9H7 coordination. 1H nuclear Overhauser effect difference (nOed) spectra indicate a preferred solution conformation in which the perfluoroalkyl group is trans to the C3a—C7a ring junction.

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.

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