Complete assignment of the 1H and 13C NMR spectra and conformational analysis of bonellin dimethyl ester

2004 ◽  
Vol 08 (12) ◽  
pp. 1376-1382 ◽  
Author(s):  
Paavo H. Hynninen ◽  
Juho Helaja ◽  
Franz-Peter Montforts ◽  
Claudia M. Müller
Keyword(s):  
Nmr Spectra ◽  
Chemical Shifts ◽  
Dimethyl Ester ◽  
Coupling Constants ◽  
Side Chain ◽  
Clear Correlation ◽  
High Tendency ◽  
H Nmr ◽  
Broad Signal ◽  
Previous Assignment

The use of a high-field NMR instrument (ν(1 H ) = 500 MHz ) and 2-dimensional NMR techniques (HMQC, HMBC, ROESY) enabled us to fully assign the 1 H and 13 C chemical shifts of bonellin dimethyl ester. The β-pyrrolic proton of C -3 appeared as a broad singlet at δ = 8.93, whereas that of C -8 gave a quartet with δ = 8.69 and 4J H - H = |1.28| Hz . The C -21 methyl protons appeared as a doublet with δ = 3.55 and 4J H - H = |1.07| Hz , while the C -71 methyl protons afforded a doublet with δ = 3.51 and 4J H - H = |1.28| Hz . These results suggest that the β-pyrrolic carbons of ring A belong to the aromatic 18 π-electron [18]diazaannulene delocalization pathway, whereas those of ring B remain outside the aromatic pathway. The broadening of the C -3 β-pyrrolic proton signal can be attributed to the allylic 3- CH - 21- CH 3 coupling and the 3- CH - 21- NH coupling. At 330 K, the tautomeric exchange 21- NH a ⇌ 23- NH b is fast and only one broad signal at δ = -2.49 is seen for these protons. The ROESY spectrum showed clear correlation signals between the 182- CH 3 and 171- CH 2 protons, the 182- CH 3 and 174- CH 3 protons, as well as between the 181- CH 3 and 17- CH protons. These results are compatible with the previous assignment that the absolute configuration at C-17 is S. Application of spin simulation enabled us to determine the chemical shifts and the 3J H - H coupling constants of the 17-propionate side-chain. The 3J H - H -values were used to calculate the populations for the 171-17 and 172-171 rotamers. A relatively high population value of 0.41 was found for the 171-17 g--rotamer, whose methoxycarbonylmethyl group points to the C -15 methine-bridge. This was interpreted as explaining the high tendency of bonellin to form anhydrobonellin. The rotational freedoms in the 13-propionate side-chain were studied by measuring the 1 H NMR spectra of the side-chain at temperatures between 300 and 195 K. At 300 K, the 131- and 132- CH 2 proton signals appeared as deceptively simple triplets, which at 195 K were split into complex multiplets. At 195 K, the signal arising from the 131- CH 2 protons exhibited more splitting, which indicates that these protons have less rotational freedom than the 132- CH 2 protons.

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.

sHigh resolution 1H nuclear magnetic resonance studies of a flavine and its product with MoCl4

1977 ◽  
Vol 55 (4) ◽  
pp. 575-582 ◽  
Author(s):  
T. Roberie ◽  
N. S. Bhacca ◽  
J. Selbin
Keyword(s):  
Aqueous Solution ◽  
Nuclear Magnetic Resonance ◽  
Binding Sites ◽  
Nmr Spectra ◽  
Coupling Constants ◽  
Side Chain ◽  
Magnetic Resonance Studies ◽  
H Nmr ◽  
Metal Atoms ◽  
1H Nuclear Magnetic Resonance

The high resolution 1H nmr spectra of the substituted flavine, 3-N-methyltetraacetylriboflavine (3-Me-TARF), and its non-aqueous solution complexes with Gd(fod)3, Eu(fod)3, MoCl4, and MoCl4•2CH3(CH2)2CN, were studied in order to try to discern the binding sites of the flavine as it attaches to the molybdenum. Evidence was found that all three metal atoms, Gd(III), Eu(III), and Mo(IV), are attached in solution not only by the primary binding (chelating) sites of the flavine, viz., the O-4 and N-5 atoms, but also by an acetyl oxygen atom, at the C-4′ site of the ribityl side chain. 300 MHz spectra of the 3-Me-TARF have permitted the coupling constants for the side chain methine and methylene protons to be obtained.

The 1H NMR spectra and the conformation of 1,6-anhydro-β-D-hexopyranoses and their triacetates

1979 ◽  
Vol 44 (6) ◽  
pp. 1949-1964 ◽  
Author(s):  
Miloš Buděšínský ◽  
Tomáš Trnka ◽  
Miloslav Černý
Keyword(s):  
Nmr Spectra ◽  
Chemical Shifts ◽  
Shift Reagent ◽  
Point Of View ◽  
Coupling Constants ◽  
Lanthanide Shift Reagent ◽  
Pyranose Ring ◽  
H Nmr ◽  
Vicinal Coupling Constants

The 1H NMR spectra of 1,6-anhydro-β-D-hexopyranoses and their triacetates, measured in hexadeuteriodimethyl sulfoxide or deuteriochloroform, confirmed the existence of these compounds in 1C4(D) conformations, with the pyranose ring partly planarized in dependence on the configuration of the substituents in positions C(2), C(3) and C(4). The effects of the substituents on the chemical shifts and the adjusted relationship for the dependence of vicinal coupling constants on the torsion angle are discussed in detail from the point of view of the determination of the configuration and the conformation of 1,6-anhydro-β-D-hexopyranoses and their derivatives. The 1H NMR spectra of triacetates were also measured in the presence of the lanthanide shift reagent, tris(1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedione) europium (III) [Eu.(FOD)3].

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.

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.

1H NMR spectra of some chloro-alkenes

1981 ◽  
Vol 46 (11) ◽  
pp. 2924-2934
Author(s):  
Seán Cawley ◽  
Jan Schraml ◽  
Petr Svoboda ◽  
Robert Ponec ◽  
Václav Chvalovský
Keyword(s):  
Nmr Spectra ◽  
Chemical Shifts ◽  
Dipole Moments ◽  
Coupling Constants ◽  
The Other ◽  
Dominant Factor ◽  
Proton Proton ◽  
Electric Field Effects ◽  
H Nmr ◽  
Proton Coupling

1H NMR spectra and electric dipole moments of a series of propene derivatives, (CH3)3-nCln.CCH=CH2 (n = 0-3), were measured and the spectra analyzed. Discrepancies in literature data on compounds with n = 0 and 3 are probably due to systematic spectrometer errors. Vinylic proton chemical shifts are found to vary linearly with n in the direction expected on the electronegativity ground (the variations with n occurs in the order HA > HB ≥ HC). Calculations show that even with the extreme reported values of C-C and C-Cl bond magnetic anisotropies, the shift variations with n cannot be accounted for by magnetic anisotropy effects of a freely rotating (CH3)3-nClnC group. Similar calculations rule out electric field effects as the dominant factor. On the other hand, the electron charge distribution, as obtained from CNDO/2 calculations, including d-orbitals and employing Del Bene-Jaffé parametrization, is linearly related to the vinylic proton shifts. This finding supports the earlier interpretation of NMR spectra of vinylsilanes in terms of back-bonding. The vinyl proton-proton coupling constants decrease with increasing n, the changes being larger in the constants which couple proton A (cis) to the other two.

Derivatives of 5α-androstan-3α- and 3β-ol with acrylonitrile side chain

1991 ◽  
Vol 56 (12) ◽  
pp. 2906-2916 ◽  
Author(s):  
Vladimír Pouzar ◽  
Hana Chodounská ◽  
Ivan Černý ◽  
Pavel Drašar
Keyword(s):  
Double Bond ◽  
Nmr Spectra ◽  
Sodium Hydride ◽  
Coupling Constants ◽  
Side Chain ◽  
H Nmr ◽  
Derivatives Of

Aldehydes II - III were reacted with diethyl cyanomethylphosphonate and sodium hydride in 1,2-dimethoxyethane to give the respective pairs of unsaturated nitriles IVa and Va, VIa and VIIa, and VIIIa and IXa differing in configuration at the 20(21)-double bond. The pure isomers were obtained by chromatography on alumina, and the configuration at the double bond in them has been established on the basis of the coupling constants J(20, 21) in their 1H NMR spectra. Nitriles IVa - VIIa and IXa were converted via the corresponding hydroxy derivatives into hemisuccinates IVd - VIId and IXd, and into β-D-glucosides IVe - VIIe and IXe.

Beiträge zur Chemie des Phosphors, 116 Kernresonanzspektren und Kristallstruktur von Tri-tert-butylcyclotriphosphan / Contributions to the Chemistry of Phosphorus, 116 NMR Spectra and Crystal Structure of Tri-tert-butylcyclotriphosphane

1982 ◽  
Vol 37 (7) ◽  
pp. 797-805 ◽  
Author(s):  
Josef Hahn ◽  
Marianne Baudler ◽  
Carl Krüger ◽  
Yi-Hung Tsay
Keyword(s):  
Nmr Spectra ◽  
Chemical Shifts ◽  
Ring Structure ◽  
Coupling Constants ◽  
Complete Analysis ◽  
X Ray ◽  
Bond Angles ◽  
Tert Butyl ◽  
H Nmr ◽  
In Cis

A complete analysis of the 31P, 13C and 1H NMR spectra of tri-tert-butyl-cyclotriphosphane (1) was carried out and the resulting NMR parameters were correlated with the X-ray data of the molecule. It was found, that increasing P-P-C-bond angles correspond to a downfield shift and an increase of the absolute values of the negative 1J(PP) and 1J(PC) coupling constants. Generally, the chemical shifts of cyclotriphosphanes as well as of larger cyclic phosphanes depend on the endo- and exocyclic bond angles, the dihedral angle between the electron lone pairs of adjacent P-atoms, and the β-effect. On the basis of the X-ray and chemical shift data of 1, the bond angles of other cyclotriphosphanes can be deduced from their δ(31P) values. 1 crystallizes triclinically in the space group P1̄ with Z = 4 formula units. The X-ray analysis confirms the NMR-spectroscopically determined three-membered ring structure with the tert-butyl substituents on either side of the ring plane. Due to steric hindrance between the two tert-butyl groups in cis position, the corresponding P-P-C-bond angles show the largest values so far observed for organylcyclophosphanes.

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.

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