scholarly journals 13C-nuclear magnetic resonance (NMR) spectra of O-acylglucoses. Additivity of shift parameters and its application to structure elucidations.

1980 ◽  
Vol 28 (7) ◽  
pp. 2065-2076 ◽  
Author(s):  
KIMIHIRO YOSHIMOTO ◽  
YOSHITAKA ITATANI ◽  
YOSHISUKE TSUDA
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nmr Spectra ◽  
13C Nuclear Magnetic Resonance ◽  
Nuclear Magnetic

13C nuclear magnetic resonance studies. 58. 13C spectra of a variety of bicyclo[2.2.2]octane derivatives. Further definition of the deshielding δ effect

1976 ◽  
Vol 54 (6) ◽  
pp. 917-925 ◽  
Author(s):  
J. B. Stothers ◽  
C. T. Tan
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nmr Spectra ◽  
Magnetic Resonance Studies ◽  
13C Nuclear Magnetic Resonance ◽  
Definition Of ◽  
C Nmr ◽  
Nuclear Magnetic

The 13C nmr spectra of 35 bicyclo[2.2.2]octane and -octene derivatives have been determined to extend our examinations of the effects of stereochemistry on the shieldings of closely neighboring carbons. This series includes a variety of methyl substituted bicyclooctanols and -octenols as well as the corresponding hydrocarbons and some bicyclooctanones. With the bicyclo[2.2.2]octane skeleton it is possible to examine an array of systems having substituents separated by three and four bonds in a variety of orientations. The interactions, termed γ and δ effects, respectively, produce distinctive shielding variations which are useful for stereochemical elucidations. Particularly interesting are the pronounced shifts observed for the carbons bearing closely neighboring substituents. Characteristically, for vicinal substituents, these carbons are shielded while for syn-axial δ interactions, these carbons are deshielded by as much as 8.6 ppm. The results are compared with the trends found in other sterically crowded Systems.

Use of a bacteriophage to depolymerize a polysaccharide to an oligosaccharide; comparison of the 1H and 13C nuclear magnetic resonance spectra of the polymer and its hexasaccharide repeating unit

1980 ◽  
Vol 58 (23) ◽  
pp. 2588-2591 ◽  
Author(s):  
Guy G. S. Dutton ◽  
Angela V. Savage ◽  
Michel Vignon
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nmr Spectra ◽  
Capsular Polysaccharide ◽  
Nuclear Magnetic Resonance Spectra ◽  
13C Nuclear Magnetic Resonance ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

A β-D-galactosidase associated with bacteriophage [Formula: see text] has been used to depolymerize the capsular polysaccharide of Klebsiella serotype K18 into the hexasaccharide corresponding to one repeating unit of the polymer. The nmr spectra of the polymer and of the oligosaccharide are comparable, leading to the conclusion that the conformations in solution of the repeating unit of the two substances are similar.

scholarly journals Identification and analysis of N-alkyl-N’-arylalkylureas by nuclear magnetic resonance

2020 ◽  
Vol 130 (1) ◽  
pp. 18-22
Author(s):  
A.A. Bakibaev ◽  
◽  
М.Zh. Sadvakassova ◽  
R.Sh. Еrkasov ◽  
А.Е. Аtagulova ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Systematic Analysis ◽  
13C Nuclear Magnetic Resonance ◽  
Nmr Methods ◽  
Nuclear Magnetic

This paper presents the results that allow one to reliably identify N-alkyl- (10 compounds) and N-alkyl-N’- arylalkylureas (12 compounds) based on the data of 1H and 13C nuclear magnetic resonance (NMR) methods. A systematic analysis has been carried out of chemical shifts in the NMR spectra of the compounds. Additionally, the authors have investigated the effect of the nitrogen atoms substituents on the chemical shifts in the NH2, NH, and C = O groups of urea.

13C nuclear magnetic resonance spectra of some C19-diterpenoid alkaloids and their derivatives

1979 ◽  
Vol 57 (13) ◽  
pp. 1652-1655 ◽  
Author(s):  
S. William Pelletier ◽  
Naresh V. Mody ◽  
Rajinder S. Sawhney
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Conformational Changes ◽  
Nmr Spectra ◽  
Diterpenoid Alkaloids ◽  
Nuclear Magnetic Resonance Spectra ◽  
13C Nuclear Magnetic Resonance ◽  
C Nmr ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

The natural abundance carbon-13 nuclear magnetic resonance spectra of some C19-diterpenoid alkaloids and their alkamines (lappaconitine, lappaconine, lapaconidine, ranaconine, 14-dehydrobrowniine, aconine, pseudoaconine, deoxyaconine, and hypaconine) have been determined at 15.03 MHz. With the aid of proton decoupling techniques, additivity relationships, and comparison with spectra of related alkaloids, self-consistent and unambiguous assignments of nearly all carbon resonances for these alkaloids have been made. Some important chemical shift trends have been observed, which are useful for identifying the basic C19-diterpenoid alkaloid skeleton and the hydroxy and methoxy group substitution patterns in these alkaloids. On the basis of 13C nmr spectra of lappaconitine and lappaconine, the anthranoyl ester moiety is assigned to the C-4 position in lappaconitine. The 13C nmr spectra of lapaconidine, aconine, and pseudoaconine taken in pyridine and chloroform have been compared to determine the conformational changes of the ring A hydroxy groups in these alkaloids.

The use of shift reagents and 13C nuclear magnetic resonance for assignment of stereochemistry to oximes

1983 ◽  
Vol 61 (11) ◽  
pp. 2616-2620 ◽  
Author(s):  
Robert R. Fraser ◽  
Raj Capoor ◽  
John W. Bovenkamp ◽  
Benoit V. Lacroix ◽  
Jack Pagotto
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nmr Spectra ◽  
The Past ◽  
Configurational Assignment ◽  
13C Nuclear Magnetic Resonance ◽  
Proton Data ◽  
Shift Reagents ◽  
C Nmr ◽  
Nuclear Magnetic

The effects of the shift reagents Eu(dpm)3 and Eu(fod)3 on the 1H and 13C nmr spectra of twelve oximes of diverse structure were examined. The proton data show that the use of proton shifts to assign oxime stereochemistry, as has been done in the past, is unreliable. In contrast, Eu(dpm)3 causes LIS values for the 13C signals of α carbons which are strongly dependent on stereochemistry. Signals for all α carbons anti to the oxime oxygen experience large downfield shifts while all syn carbons are either unaffected or shifted upfield. Thus the effects of Eu(dpm)3 on these 13C signals provides an unambiguous method of configurational assignment to oximes. The effects of Eu(fod)3, though similar to Eu(dpm)3, were less consistent and thus less promising for making configurational assignments.

13C nuclear magnetic resonance studies. 55. A comparison of the stereochemical dependence of γ- and δ-substituent effects on 13C shieldings in several norbornanols and norbornenols

1976 ◽  
Vol 54 (8) ◽  
pp. 1211-1221 ◽  
Author(s):  
J. B. Stothers ◽  
C. T. Tan ◽  
K. C. Teo
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nmr Spectra ◽  
Substituent Effects ◽  
Magnetic Resonance Studies ◽  
Considerable Potential ◽  
13C Nuclear Magnetic Resonance ◽  
Insight Into ◽  
C Nmr ◽  
Nuclear Magnetic

The 13C nmr spectra of a series of 50 methyl substituted norbornanols have been determined to gain further insight into the nature of stereochemical effects on the shieldings of carbons having closely neighboring substituents. The relatively rigid norbornyl skeleton permits examination of a variety of orientations of substituents separated by three and four bonds, the γ and δ interactions, respectively. While methyl carbons close to γ substituents exhibit upfield shifts, as is well established, methyl carbons close to δ substituents are significantly deshielded. Even more striking shifts are found for the carbons bearing these closely lying groups. The penultimate carbons in a fragment having a δ interaction between terminal groups show deviations of up to +11 ppm from the shieldings predicted by simple additivity. For fragments having a corresponding γ interaction, the penultimate carbons absorb as much as −10 ppm from the values expected by additivity. These deviations have considerable potential for stereochemical assignments and offer a challenge for theoretical interpretation.Some norbornenols and the acetates of several of the norbornanols were also included in this series and the latter shieldings are compared briefly with those observed for the parent alcohols.

Diels-Alder Adducts of 3,6-Dibromophencyclone with Short-Chain N-n-Alkylmaleimides: 1H and 13C Nuclear Magnetic Resonance Studies of Hindered Rotations and Magnetic Anisotropy, and Ab Initio Calculations for Optimized Structures

2005 ◽  
Vol 59 (3) ◽  
pp. 376-384
Author(s):  
Kerstin Rosmarion ◽  
Robert Rothchild
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Ab Initio ◽  
Nmr Spectra ◽  
Proton Nmr ◽  
Diels Alder ◽  
Basis Set ◽  
Hartree Fock ◽  
13C Nuclear Magnetic Resonance ◽  
Nuclear Magnetic

3,6-Dibromophencyclone, 2, reacted with N-ethylmaleimide, 3a; N- n-propylmaleimide, 3b; and N- n-butylmaleimide, 3c; to form the corresponding Diels-Alder adducts, 4a, 4b, and 4c. The nuclear magnetic resonance (NMR) spectra of the adducts were studied at ambient temperatures at 300 MHz for proton and 75 MHz for carbon-13. Full proton assignments were achieved by high-resolution COSY45 spectra for the aryl proton regions. Rigorous assignments for protonated carbons were obtained with the heteronuclear chemical shift correlation spectra (HETCOR). Slow exchange limit (SEL) spectra were observed for both proton and carbon-13 NMR for each adduct, with slow rotation on the NMR timescales for the unsubstituted bridgehead phenyl groups. Endo Diels-Alder adduct stereochemistry was supported by substantial magnetic anisotropic shielding effects in the 1H NMR spectra of the alkyl groups. Proton NMR shifts are compared with those previously reported for the corresponding adducts, 5b and 5c, obtained from 3b and 3c, respectively, with the parent compound, phencyclone, 1. Results of ab initio molecular modeling calculations at the Hartree-Fock level using the LACVP* basis set for conformers of the dibrominated adducts, 4a–4c, are presented, together with HF/6–31G* results for the non-brominated adducts, 5a, 5b, and 5c. Novel aspects of this present work include: (a) attempts to quantitatively evaluate alkyl proton NMR shielding magnitudes in the adducts, relative to maleimide precursors, and (b) use of ab initio Hartree-Fock level calculations to try to reconcile adduct geometries with the observed shielding magnitudes. Our results here complement and extend studies of: (a) adducts of the parent phencyclone with straight-chain N- n-alkylmaleimides, and (b) adducts of 3,6-dibromophencyclone with other symmetrical dienophiles.

scholarly journals P052 Nuclear magnetic resonance metabolomic profiling of IBD patients under anti-TNF treatment. Are the pathways network deregulated?

2020 ◽  
Vol 14 (Supplement_1) ◽  
pp. S160-S160
Author(s):  
S Notararigo ◽  
M Martin-Pastor ◽  
J E Dominguez Munoz ◽  
M Barreiro-de Acosta
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nmr Spectra ◽  
Mononuclear Cells ◽  
High Rate ◽  
Resonance Spectroscopy ◽  
Serum Samples ◽  
Spectral Window ◽  
Metabolomic Study ◽  
Nuclear Magnetic

Abstract Background The deregulation of immune system cell response implies loss of T-cell apoptosis, high rate of proinflammatory cytokines production and subsequent exacerbate activation of TNF-α pathway. The use of biologic antibody decrease inflammation rate and symptoms, but it remains unclear if it has a direct effect on the pathways activation/inactivation on peripheral blood mononuclear cells (PBMCs). The aim of this study is evaluate the role of nuclear magnetic resonance spectroscopy (NMR) applied to the metabolomic study of serum samples isolated from fresh blood from inflammatory bowel disease (IBD) patients under IFX treatment to understand the activated/inactivated pathways of PBMCs. Methods A case–control study was performed. Inclusion criteria were IBD patients under IFX treatment. Blood samples were obtained in Crohn’s disease (CD) and ulcerative colitis (UC) patients before IFX and in healthy controls (CTRL). CD patients were divided into subgroups according to the gut affected, in Ileocolic (IC), ileum and colon. NMR samples of the serum were collected and measured according to Standard Operation Procedures. Three types of NMR spectra were measured for each serum sample (1Hnoepresat, 1Hcpmgpresat and 1HDfilterpresat). The signal in each NMR spectrum was integrated in a series of equidistant little portion of the spectrum called buckets of a constant width of 0.04 ppm, covering the complete 1H NMR spectral window from −5 to 14 ppm. Buckets in regions depleted from signal at the two extremes of the spectrum were discarded as well as those in the proximity of the water peak at ca. 4.7 ppm which was affected by the presaturation. The vectors corresponding to a number of samples of two or more groups can be rapidly analysed using Multivariant Statistical Analysis methods. Results Twenty-two IBD patients (12 CD and nine UC) were included, 10 CTRL were also included. The metabolomic analyses of the NMR spectra of the serum of the different patients and control groups by the fingerprinting and targeting profiling strategies provided OPLS-DA statistical models (Figure 1) that permitted the successful classification of certain groups of samples which are summarised in Table 1. Conclusion The results of this pilot NMR metabolomic study of serum samples of IBD found a series of spectral fingerprints that are able to discriminate between groups of patients CTRL and CD, which underlines its potential use for the diagnosis of the disease.

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