An 1H nuclear magnetic resonance study of derivatives of 3-hydroxy-12,13-epoxytrichothec-9-enes

1987 ◽  
Vol 65 (9) ◽  
pp. 2254-2262 ◽  
Author(s):  
Marc E. Savard ◽  
Barbara A. Blackwell ◽  
Roy Greenhalgh
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Chair Conformation ◽  
Nuclear Magnetic Resonance Study ◽  
Coupling Constants ◽  
Substitution Pattern ◽  
Nuclear Magnetic Resonance Spectra ◽  
1H Nuclear Magnetic Resonance ◽  
Nuclear Magnetic

The 250-MHz 1H nuclear magnetic resonance spectra of 36 natural and synthetic trichothecenes have been analyzed and the chemical shifts as well as the vicinal and long-range coupling constants determined. Knowledge of the 16-CH3 chemical shift enables the substitution pattern of the A ring to be defined. Similarly, oxygenation in the C ring results in easily identifiable resonances. The J2,3 and J3,4 values define the configuration of substituents at C-3 and C-4, while the configuration at C-7 and C-8 can be defined by the J7,8, J7α,11, and J7β,15 values. The trichothecene ring system adopts the most stable A-half-chair, B-chair conformation in solution. The correlations obtained allow easy structural determination of unknown trichothecenes.

scholarly journals Carbon-13 nuclear magnetic resonance spectra of oxazoles

1979 ◽  
Vol 57 (23) ◽  
pp. 3168-3170 ◽  
Author(s):  
Henk Hiemstra ◽  
Hendrik A. Houwing ◽  
Okko Possel ◽  
Albert M. van Leusen
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Proton Coupling ◽  
Nuclear Magnetic Resonance Spectra ◽  
C Nmr ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

The 13C nmr spectra of oxazole and eight mono- and disubstituted derivatives have been analyzed with regard to the chemical shifts and the various carbon–proton coupling constants of the ring carbons. The data of the parent oxazole are compared with thiazole and 1-methylimidazole.

13C nuclear magnetic resonance spectra of 3,6-disubstituted pyridazines

1991 ◽  
Vol 69 (6) ◽  
pp. 972-977 ◽  
Author(s):  
Gottfried Heinisch ◽  
Wolfgang Holzer
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Molecular Orbital Calculations ◽  
Nuclear Magnetic Resonance Spectra ◽  
13C Nuclear Magnetic Resonance ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

The 13C nuclear magnetic resonance spectra of 17 3,6-disubstituted pyridazine derivatives have been systematically analyzed. Chemical shifts and various 13C, 1H coupling constants are reported. Attempts were made to correlate these data with results obtained from semiempirical molecular orbital calculations as well as with substituent electronegativities and Taft's substituent constants σI and σR0. Key words: 3,6-disubstituted pyridazines, 13C NMR spectroscopy, 13C, 1H spin coupling constants.

Nuclear Magnetic Resonance Studies on Fluorides of Trivalent Phosphorus

1965 ◽  
Vol 20 (2) ◽  
pp. 104-109 ◽  
Author(s):  
G. S. Reddy ◽  
R. Schmutzler
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Trivalent Phosphorus ◽  
Magnetic Resonance Studies ◽  
Regular Change ◽  
Nuclear Magnetic Resonance Spectra ◽  
Multiple Substitution ◽  
Nuclear Magnetic

The P31, F19, and H1 nuclear magnetic resonance spectra of a new series of compounds of the types (RO)nPF3-n and (R2N)nPF3-n (n = 1,2) have been studied. A regular change in the chemical shifts and coupling constants has been observed with multiple substitution. The changes in the coupling constants have been explained on the basis of the electronegativity of the atoms attached to phosphorus. Some long-range coupling constants between hydrogen and fluorine separated by five bonds were observed.

A 1H and 13C nuclear magnetic resonance study of nucleosides with methylated pyrimidine bases

1982 ◽  
Vol 60 (24) ◽  
pp. 3026-3032 ◽  
Author(s):  
Frank E. Hruska ◽  
Wayne J. P. Blonski
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Nuclear Magnetic Resonance Study ◽  
Coupling Constants ◽  
Magnetic Resonance Data ◽  
Proton Coupling ◽  
13C Nuclear Magnetic Resonance ◽  
Pyrimidine Bases ◽  
Nuclear Magnetic

Alkylated pyrimidine bases are of interest from the viewpoint of mutagenesis and carcinogenesis. 1H nuclear magnetic resonance data are presented for a series of ribosides and arabinosides alkylated at the O2,O4, N3, and C5 positions of the pyrimidine base. The data provide information about the stereochemical effects of base methylation. The J(5—6) proton coupling constants show that O-alkylation leads to a decrease in the π-bond order of the C5—C6 bond. The 13C chemical shifts are related to the tautomeric changes effected by O-alkylation.

31P and 19F Nuclear Magnetic Resonance Studies of Phosphorus-Fluorine Compounds

1970 ◽  
Vol 25 (11) ◽  
pp. 1199-1214 ◽  
Author(s):  
G. S. Reddy ◽  
R. Schmutzler
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Coordination Number ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Magnetic Resonance Studies ◽  
Nuclear Magnetic Resonance Spectra ◽  
Fluorine Compounds ◽  
Nuclear Magnetic

The nuclear magnetic resonance spectra (31P, 19F) of a variety of compounds containing phosphorus-fluorine bonds have been studied, in continuation of earlier investigations on the same type of compounds.The previously observed relationship between coordination number of phosphorus and δP was generally confirmed, i. e. δP becomes more positive as the coordination number around phosphorus increases. No meaningful substitution rules, either for chemical shifts or for P-F coupling constants, could be established. The data obtained are discussed qualitatively in relation to the electronegativity of the substituents and to the coordination number of phosphorus. Data on the preparation and characterization of numerous phosphorus-fluorine compounds are also included.

scholarly journals Application of multiplet structure deconvolution to extract scalar coupling constants from 1D nuclear magnetic resonance spectra

2021 ◽  
Vol 2 (2) ◽  
pp. 545-555
Author(s):  
Damien Jeannerat ◽  
Carlos Cobas
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Scalar Coupling ◽  
Order Effects ◽  
Multiplet Structure ◽  
First Order ◽  
Nuclear Magnetic Resonance Spectra ◽  
Nuclear Magnetic

Abstract. Multiplet structure deconvolution provides a robust method to determine the values of the coupling constants in first-order 1D nuclear magnetic resonance (NMR) spectra. Functions simplifying the coupling structure for partners with spin larger than 1/2 and for doublets with unequal amplitudes were introduced. The chemical shifts of the coupling partners causing mild second-order effects can, in favourable cases, be calculated from the slopes measured in doublet structures. Illustrations demonstrate that deconvolution can straightforwardly analyse multiplet posing difficulties to humans and, in some cases, extract coupling constants from unresolved multiplets.

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