13C and 1H NMR spectra of all methyl O-benzoyl-β-D-xylopyranosides. nonadditivity of acylation effects on 13C chemical shifts in deutoriochloroform solutions

1983 ◽  
Vol 48 (3) ◽  
pp. 877-888 ◽  
Author(s):  
Eva Petráková ◽  
Jan Schraml
Keyword(s):  
1H Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Conformational Heterogeneity ◽  
Additivity Rule ◽  
Homonuclear Decoupling ◽  
First Order ◽  
H Nmr ◽  
C Nmr

All methyl O-benzoyl-β-D-xylopyranosides have been prepared and their 1H and 13C NMR spectra measured in deuteriochloroform solutions. The 1H NMR spectra were analysed to the first order and assigned with the aid of homonuclear decoupling. The 13C chemical shifts were assigned through heteronuclear selective decouling experiments. Some of the 13C chemical shifts observed in di- and tri-O-benzoyl derivatives differ considerably from those calculated according to the direct additivity rule from the shifts in the mono derivatives. It is shown that the nonadditivity is due to a conformational heterogeneity of the series of investigated compounds dissolved in deuteriochloroform. The heterogeneity is evidenced by the vicinal 1H-1H coupling constants and by 13 chemical shifts of C(1) methoxyl carbon atoms.

15N, 13C, and 1H NMR spectra of acylated ureas and thioureas

1987 ◽  
Vol 52 (10) ◽  
pp. 2474-2481 ◽  
Author(s):  
Josef Jirman ◽  
Antonín Lyčka
Keyword(s):  
1H Nmr ◽  
Electron Acceptor ◽  
Sulfur Atom ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
1H Nmr Spectra ◽  
Coupling Constants ◽  
Nmr Chemical Shifts ◽  
H Nmr ◽  
Better Than

A series of 1-acylated and 1,3-diacylated (acyl = acetyl or benzoyl) ureas and thioureas have been prepared and their proton-coupled and proton-decoupled 15N, 13C, and 1H NMR spectra have been measured. All the signals have been assigned. The 15N NMR chemical shifts in 1-acylated ureas and thioureas are shifted downfield as compared with δ(15N) of urea and thiourea, resp. This shift is greater for N-1 than for N-3 nitrogen atoms in both the series. When comparing acylureas and acylthioureas it is obvious from the Δδ(15N) differences that the CS group is better than CO group in transferring the electron-acceptor effect of acyl group. The proton-coupled 15N NMR spectra of the acylureas dissolved in hexadeuteriodimethyl sulphoxide exhibit a doublet of NH group and a triplet of NH2 group at 25 °C. At the same conditions the acylthioureas exhibit a doublet of NH group, the NH2 group signal being split into a doublet of doublets with different coupling constants 1J(15N, H). The greater one of these coupling constants is due to the s-trans proton with respect to the sulfur atom of the thiourea.

1H NMR spectra and the conformation of 1,6 : 2,3- and 1,6 : 3,4-dianhydro-β-D-hexopyranoses and their derivatives

1979 ◽  
Vol 44 (6) ◽  
pp. 1965-1983 ◽  
Author(s):  
Miloš Buděšínský ◽  
Miloslav Černý ◽  
Tomáš Trnka ◽  
Soňa Vašíčková
Keyword(s):  
Hydrogen Bonds ◽  
1H Nmr ◽  
Torsion Angle ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Point Of View ◽  
Coupling Constants ◽  
H Nmr ◽  
Vicinal Coupling Constants ◽  
Intramolecular Hydrogen

The 1H NMR spectra of 1,6 : 2,3- and 1,6 : 3,4-dianhydro-β-D-hexopyranoses and their acetyl-, trichloroacetylcarbamoyl- and 2- or 4-deoxy derivatives were measured in hexadeuteriodimethyl sulfoxide or deuteriochloroform. In these solvents dianhydro derivatives assume the half-chair conformations 5H0 or 1H0 which are not distinctly affected by the presence of substituents. The effects of substituents on the chemical shifts and the adjusted relation for the dependence of the vicinal coupling constants on the torsion angle are discussed from the point of view of conformation and the interactions of the oxirane ring with the oxygen O(5) and O(6) of the 1,6-anhydropyranose skeleton. Intramolecular hydrogen bonds in free dianhydrohexopyranoses were measured and identified in tetrachloromethane solution.

Conformational structure of ethylene glycol dibenzoate. Vibrational and NMR spectra

1981 ◽  
Vol 46 (8) ◽  
pp. 1913-1929 ◽  
Author(s):  
Bohdan Schneider ◽  
Pavel Sedláček ◽  
Jan Štokr ◽  
Danica Doskočilová ◽  
Jan Lövy
Keyword(s):  
Ethylene Glycol ◽  
Vibrational Spectra ◽  
Nmr Spectra ◽  
Coupling Constants ◽  
Conformational Structure ◽  
Infrared And Raman Spectra ◽  
H Nmr ◽  
Liquid States ◽  
Crystalline Forms ◽  
C Nmr

It was found that three crystalline forms of ethylene glycol dibenzoate can be prepared. Infrared and Raman spectra of these three forms, as well as of the glassy and liquid states, were measured. From 3JHH coupling constants obtained by analysis of the 13C satellite band of the -CH2- group in 1H NMR spectra, and from the 3JCH coupling constants of the -CO.O.CH2- fragment obtained by analysis of the carbonyl band in 13C NMR spectra it was found that in the liquid state the -CH2-CH2- group exists predominantly in the gauche conformational structure, and the bonds C-O-C-C assume predominantly a trans orientation. The results of the analysis of NMR and vibrational spectra were used for the structural interpretation of conformationally sensitive bands in vibrational spectra of ethylene glycol dibenzoate.

Carbon-13 and nitrogen-14 NMR spectra of 1-(substituted phenyl)pyridinium salts

1980 ◽  
Vol 45 (10) ◽  
pp. 2766-2771 ◽  
Author(s):  
Antonín Lyčka
Keyword(s):  
Heavy Water ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Pyridinium Salts ◽  
Nmr Signals ◽  
C Nmr

The 13C and 14N NMR spectra of 1M solutions of 1-(substituted phenyl)pyridinium salts (4-CH3, 4-OCH3, H, 4-Cl, 4-Br, 4-I, 3-NO2, 4-NO2, 2,4-(NO2)2 (the 13C NMR only)) have been measured in heavy water at 30 °C. The 13C and 14N chemical shifts, the 1J(CH) coupling constants, some 3J(CH) coupling constants, and values of half-widths Δ 1/2 of the 14N NMR signals are given. The 13C chemical shifts of C(4) correlate with the σ0 constants (δC(4) = (1.79 ± 0.097) σ0 + (147.67 ± 0.041)), whereas no correlation of the nitrogen chemical shifts with the σ constants has been found. The half-widths Δ 1/2 correlate with the σ0 constants (Δ 1/2 = (76.2 ± 4.9) σ0 + (106.4 ± 2.2)) except for 1-phenylpyridinium chloride.

scholarly journals 13C and 1H NMR Spectra of Synthetic (25R)-5α-Spirostanes

1999 ◽  
Vol 23 (1) ◽  
pp. 48-49
Author(s):  
Martín A. Iglesias Arteaga ◽  
Carlos S. Pérez Martinez ◽  
Roxana Pérez Gil ◽  
Francisco Coll Manchado
Keyword(s):  
1H Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
1H Nmr Spectra ◽  
H Nmr ◽  
C 23 ◽  
Main Effects ◽  
Nmr Signals

The assignment of 13C and 1H NMR signals of synthetic (25 R)-5α-spirostanes is presented; the main effects on chemical shifts due to substitution at C-23 are briefly discussed.

E-Homolupane Derivatives Substituted in Position 17 and 22a. 1H NMR, 13C NMR and IR Spectra

1995 ◽  
Vol 60 (4) ◽  
pp. 619-635 ◽  
Author(s):  
Václav Křeček ◽  
Stanislav Hilgard ◽  
Miloš Buděšínský ◽  
Alois Vystrčil
Keyword(s):  
Nmr Spectra ◽  
2D Nmr ◽  
Coupling Constants ◽  
Side Chain ◽  
Oxidation Reactions ◽  
H Nmr ◽  
Complete Assignment ◽  
Nmr Techniques ◽  
Intramolecular Association ◽  
C Nmr

A series of derivatives with various oxygen functionalities in positions 17,22a or 19,20 was prepared from diene I and olefin XVI by addition and oxidation reactions. The structure of the obtained compounds was confirmed by 1H NMR, 13C NMR and IR spectroscopy. The kind of intramolecular association of the 17α-hydroxy group was studied in connection with modification of the side chain and substitution in position 22a. Complete assignment of the hydrogen signals and most of the coupling constants was accomplished using a combination of 1D and 2D NMR techniques. The 1H and 13C NMR spectra are discussed.

Phosphinsubstituierte Chelatliganden, XXIII [1] Darstellung und NMR-Spektren von Alkyl-arylphosphinothioformamiden, R(Ph)PC(S)NHMe / Phosphine-Substituted Chelate Ligands, XXIII [1] Synthesis and NMR Spectra of Alkyl-arylphosphinothioformamides, R(Ph)PC(S)NHMe

1987 ◽  
Vol 42 (1) ◽  
pp. 77-83 ◽  
Author(s):  
Udo Kunze ◽  
Rolf Tittmann
Keyword(s):  
Chemical Shift ◽  
Linear Correlation ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Cone Angle ◽  
Coupling Constants ◽  
Methyl Isothiocyanate ◽  
Signal Sets ◽  
The Asymmetry ◽  
C Nmr

Abstract A series of alkyl-arylsubstituted N-methyl phosphinothioformamides, R(Ph)PC(S)NHMe (2 a-g), with varying bulkiness of the alkyl rest was synthesized from the racemic secondary phosphines 1a-g and methyl isothiocyanate. 1H and 13C NMR spectra of 2a−g reveal signal sets of diastereotopic nuclei due to the asymmetry of the molecule. The chemical shift and coupling constants were confirmed by simulation in case of 2b, c. The vicinal 31P−13C couplings of the menthyl and neomenthyl compounds 2f, g show an "anti-Karplus" behaviour (3J(gauche) > 3J(trans)) and allow the conformational assignment of the alicyclic group. The 31P chemical shifts of 2a−d give a linear correlation with the cone angle of the alkyl substituents quoted from literature.

13C-NMR-Spektroskopie an polycyclischen Aromaten, II. Die 13C-NMR-Spektren von 1- und 2-Fluornaphthalin. Überprüfung der Signalzuordnung und Untersuchung der Substituenteneffekte auf die chemischen Verschiebungen / 13C NMR Spectroscopy of Polycyclic Aromatics, II. The 13C NMR Spectra of 1- and 2-Fluoronaphthalene. Reexamination of Signal Assignments and Investigation of Substituent Effects on Chemical Shifts

1975 ◽  
Vol 30 (9-10) ◽  
pp. 788-793 ◽  
Author(s):  
Ludger Ernst
Keyword(s):  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Double Resonance ◽  
Substituent Effects ◽  
13C Nmr Spectroscopy ◽  
Polycyclic Aromatics ◽  
H Nmr ◽  
Iterative Analysis ◽  
C Nmr

During a reinvestigation of the 13C NMR spectra of 1-fluoronaphthalene (1) and of 2-fluoronaphthalene (2) at 20 and 25.16 MHz, uncertainties that existed in the literature about signal assignments for 1 could be cleared. In the spectral analyses for 2 given so far, five out of ten signals were incorrectly assigned. The corrected assignment is supported by extensive 13C{1H} double resonance experiments, by recording of proton-coupled 13C and 13C{19F} spectra and by off-resonance 13C{1H} noise-decoupling. The results show a strong + M-effect of the fluorine substituents on 13C chemical shifts similar to the effects of OH and OCH3 groups. 1H NMR spectra of 1 and 2 could be partially assigned by decoupling of the 19F resonances and by iterative analysis.

Neue Untersuchung über Inhaltsstoffe aus Aloe-und Rhamnus-Arten, XV [1] Homonataloin A und B aus Aloe lateritia: Reindarstellung, Konstitutions-und Konfigurationsaufklärung der Diastereomeren / A New Investigation on Constituents of Aloe and Rhamnus Species, XV [1] Hom onataloins A and B from Aloe lateritia: Isolation, Structure and Configurational Determ ination of the Diastereomers

1991 ◽  
Vol 46 (3-4) ◽  
pp. 177-182 ◽  
Author(s):  
Hans-W. Rauwald ◽  
Deo-D. Niyonzima
Keyword(s):  
Chemical Shifts ◽  
Optical Rotation ◽  
Coupling Constants ◽  
Cd Spectra ◽  
Large Coupling ◽  
H Nmr ◽  
Leaf Exudate ◽  
Hydroxyl Protons ◽  
Nmr Signals ◽  
C Nmr

From the leaf exudate of Aloe lateritia ENGLER the C-glucosyl com pounds homonataloin, aloeresin A and aloesin (synon. aloeresin B) were isolated together with the anthraquinone nataloeem odin-8-methylether and spectroscopically identified. Hom onataloin, widely distributed in Aloe species, was separated into homonataloin A and B by combined TLC and DCCC. In their 1 D and 2D 1H NMR spectra only the shifts of the 2′-hydroxyl protons of both glucosyl residues differ significantly, indicative of 10 S (A) resp. 10 S (B) configurations. In both com pounds the anthrone is in β-position of the D-glucopyranosyl, as determined by the large coupling constants of the anomeric protons. The 13C NMR signals are unambiguously assigned by the use of DEPT, APT and gated-decoupling methods. Only the chemical shifts of C -11 and C -14 show significant differences between both diastereomers due to the adjacent 2′-sugar hydroxyls. The two homonataloins differ mostly in optical rotation and circulardichroism due to different configurations at C - 10 of the anthrone part. The absolute configurations of the diastereomers are determined by correlation of their CD spectra with the CD spectra of the structural analogues 7-hydroxyaloins A and B, which shows that hom onataloin A is the 10 S, 1′S-compound and that homonataloin B has 10 R, 1′S-configuration.

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.

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