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.

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.

Carbon-13 nuclear magnetic resonance study of phenyl derivatives of B, Si, Sn, P, and Te fluorides

1993 ◽  
Vol 71 (4) ◽  
pp. 526-528 ◽  
Author(s):  
Chengrui Wang ◽  
Yuxiang Mo ◽  
Meehae Jang ◽  
Alexander F. Janzen
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Central Element ◽  
Nuclear Magnetic Resonance Study ◽  
Magnetic Resonance Data ◽  
Resonance Data ◽  
Experimental Values ◽  
Derivatives Of ◽  
Nuclear Magnetic

13C nuclear magnetic resonance data for a variety of phenyl derivatives of boron, silicon, tin, phosphorus, and tellurium fluorides are presented. Neutral, anionic, and cationic complexes are included and the coordination number of the central element varies from 3 to 6. Empirical equations of the 13C chemical shifts of the benzene ring have been deduced by taking into consideration the charge density, dipole moment, and binding energy, and the 13C chemical shifts calculated from these equations deviate from the experimental values by up to 1.4 ppm, but mostly less than 0.7 ppm.

Nuclear Magnetic Resonance Study of the Hydrolysis of Diethyl Methylphosphonite

1968 ◽  
Vol 22 (2) ◽  
pp. 95-98 ◽  
Author(s):  
Kenneth E. Daugherty ◽  
William A. Eychaner ◽  
John I. Stevens
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Analytical Data ◽  
Nuclear Magnetic Resonance Study ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Proton Nuclear Magnetic Resonance ◽  
Spin Spin Coupling ◽  
Nuclear Magnetic

The products of the hydrolysis reactions of diethyl methylphosphonite at room temperature have been elucidated by means of proton nuclear magnetic resonance. The reaction was followed by observing the methyl-hydrogen resonance, phosphorus-hydrogen resonance, methylenehydrogen resonance, and hydroxyl-hydrogen resonance. Upon addition of up to one mole of water per mole of diethyl methylphosphonite, ethyl hydrogen methylphosphinate was produced in a very rapid and complete reaction. Upon addition of greater than one mole of water—up to two moles of water per mole of diethyl methylphosphonite—the ethyl hydrogen methylphosphinate that was produced was further hydrolyzed to dihydrogen methylphosphinate in a very slow reaction. At ratios of two or more moles of water per mole of diethyl methylphosphonite, only dihydrogen methylphosphinate and ethanol were observed in solution after the reactions had come to completion. Trivalent phosphorus hydrolysis products were not observed in this reaction sequence. The chemical shifts, spin—spin coupling constants, and analytical data are described.

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.

Nucleosides. XLIX. Nuclear magnetic resonance studies of 2′-and 3′-halogeno nucleosides. The conformations of 2′-deoxy-2′-fluorouridine and 3′-deoxy-3′-fluoro-β-D-arabinofuranosyluracil

1968 ◽  
Vol 46 (7) ◽  
pp. 1131-1140 ◽  
Author(s):  
Robert J. Cushley ◽  
John F. Codington ◽  
Jack J. Fox
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Proton Proton ◽  
Pyrimidine Nucleosides ◽  
Magnetic Resonance Data ◽  
Twist Conformation ◽  
Resonance Data ◽  
Nuclear Magnetic

Nuclear magnetic resonance data for a series of 2′-halogeno and 3′-halogeno pyrimidine nucleosides are presented. Using a combination of proton–proton and proton–fluorine couplings vs. dihedral angle values 2′-deoxy-2′-fluorouridine is proposed to have an envelope conformation with C–3′ endo, and 1-(3-deoxy-3-fluoro-β-D-arabinofuranosyl)uracil proposed to have a twist conformation with O-ring endo and C–1′ exo. Correlations between substituent electronegativity and both vicinal coupling constants and internal chemical shifts are discussed.Syntheses of several new 2′-halogeno and 3′-halogeno nucleosides are described.

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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