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.

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.

scholarly journals Reactions of 3-(p-substituted-phenyl)-5-chloromethyl-1,2,4-oxadiazoles with KCN leading to acetonitriles and alkanes via a non-reductive decyanation pathway

2018 ◽  
Vol 14 ◽  
pp. 3011-3017
Author(s):  
Akın Sağırlı ◽  
Yaşar Dürüst
Keyword(s):  
Nmr Spectra ◽  
2D Nmr ◽  
Synthetic Route ◽  
X Ray ◽  
H Nmr ◽  
2D Nmr Spectra ◽  
Tof Ms ◽  
C Nmr

The present work describes an unfamiliar reaction of 5-(chloromethyl)-3-substituted-phenyl-1,2,4-oxadiazoles with KCN affording trisubstituted 1,2,4-oxadiazol-5-ylacetonitriles and their parent alkanes, namely, 1,2,3-trisubstituted-1,2,4-oxadiazol-5-ylpropanes. To the best of our knowledge, the current synthetic route leading to decyanated products will be the first in terms of a decyanation process which allows the transformation of trisubstituted acetonitriles into alkanes by the incorporation of KCN with the association of in situ-formed HCN and most likely through the extrusion of cyanogen which could not be detected or isolated. In addition, the plausible mechanisms were proposed for both transformations. The structures of the title compounds were identified by means of IR, 1H NMR, 13C NMR, 2D NMR spectra, TOF–MS and X-ray measurements.

5,10,15-Triarylcorrole atropisomerism

2020 ◽  
Vol 24 (01n03) ◽  
pp. 153-160
Author(s):  
Martina Bischetti ◽  
Giuseppe Pomarico ◽  
Sara Nardis ◽  
Federica Mandoj ◽  
Daniel O. Cicero ◽  
...  
Keyword(s):  
Nmr Spectra ◽  
Aryl Ring ◽  
H Nmr ◽  
Ring Rotation ◽  
Complete Assignment ◽  
Nmr Techniques ◽  
Thermodynamic Factors

A series of 5,10,15-triarylcorroles has been prepared, with the meso-aryl rings functionalized with different substituents to investigate their influence on the aryl ring rotation with respect to the corrole plane. The study has been carried out by different NMR techniques, allowing the complete assignment of the 1H NMR spectra and giving insights on the kinetic and thermodynamic factors driving the atropisomerism in triarylcorrole derivatives.

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.

On the chemistry and high field nuclear magnetic resonance spectroscopy of rapamycin

1980 ◽  
Vol 58 (6) ◽  
pp. 579-590 ◽  
Author(s):  
John A. Findlay ◽  
Lajos Radics
Keyword(s):  
High Field ◽  
Nmr Spectra ◽  
Resonance Spectroscopy ◽  
X Ray ◽  
Conformational Isomers ◽  
H Nmr ◽  
Neutral Compounds ◽  
Complete Assignment ◽  
Hydrolysis Of ◽  
C Nmr

Base catalysed hydrolysis of rapamycin (C51H79NO13) affords six neutral compounds identified by chemical and spectroscopic means as 2a, 3b, 3d, 5, 2,4-dimethylphenol, and L(−)-piperidine-2-carboxylic acid 6, and whose generation has been plausibly rationalized. These findings as well as detailed analyses of 13C nmr and 1H nmr spectra provide independent corroboration of the X-ray derived rapamycin crystal structure 1. Structurally homogeneous in the solid state, rapamycin is found to occur in solutions as a mixture of two conformational isomers (approximately 4:1). Through nearly complete assignment of the high field 1H (400 MHz) and 13C (100.6 MHz) nmr spectra, the isomerism is shown to be associated with trans–cis rotation of an amidic bond within the 31-membered macrolide ring. The predominant form corresponds to the conformer portrayed by X-ray analysis.

MWL fraction with a high concentration of lignin-carbohydrate linkages: Isolation and 2D NMR spectroscopic analysis

Holzforschung ◽  
2007 ◽  
Vol 61 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Mikhail Yu. Balakshin ◽  
Ewellyn A. Capanema ◽  
Hou-min Chang
Keyword(s):  
Loblolly Pine ◽  
Spectroscopic Analysis ◽  
Direct Detection ◽  
2D Nmr ◽  
Side Chain ◽  
High Concentration ◽  
Hmbc Correlation ◽  
Nmr Techniques ◽  
C Nmr ◽  
Hmbc Technique

Abstract A preparation enriched in lignin-carbohydrate fragments (LCC-AcOH) was isolated in the course of purification of loblolly pine crude milled wood lignin (MWL). The preparation contained approximately equal amounts of lignin and carbohydrates, with high amounts of arabinose and galactose compared to their levels in wood. LCC-AcOH was investigated by 2D 1H-13C (HMQC and HMBC) correlation NMR techniques and quantitative 13C NMR. The HMQC spectra allowed direct detection of phenyl glycoside, ester and benzyl ether lignin-carbohydrates linkages in high amounts. The assignment of these structures was supported by the HMBC technique. It is noteworthy that in the ester lignin-carbohydrate linkages, a uronic acid residue was attached not to the benzylic position of lignin, as commonly believed, but to the γ-position of the side chain.

Isolation and Structure Determination of Three New Sesquiterpenoids from Achillea millefolium

2012 ◽  
Vol 67 (5) ◽  
pp. 421-425 ◽  
Author(s):  
Umar Farooq ◽  
Afsar Khan ◽  
Saleha Suleman Khan ◽  
Shazia Iqbal ◽  
Rizwana Sarwar ◽  
...  
Keyword(s):  
Sesquiterpene Lactone ◽  
2D Nmr ◽  
Achillea Millefolium ◽  
Two Dimensional ◽  
H Nmr ◽  
Whole Plant ◽  
Phytochemical Investigation ◽  
Nmr Techniques ◽  
C Nmr

Phytochemical investigation of the whole plant of Achillea millefolium led to the isolation of three new sesquiterpenes which were trivially named as sesquiterpene lactone-esters A and B (1 and 2), and sesquiterpene lactone-diol (3). The structures of these compounds were determined with the help of one- and two-dimensional (1D and 2D) NMR techniques including 1H NMR, 13C NMR, HMQC, HMBC, COSY, and NOESY experiments.

NMR-spektroskopische Untersuchung des Problems der Valenzisomerie zwischen 1,2-Dithiin und (Z)-But-2-en-1,4-dithion / NMR Spectroscopic Investigation Concerning the Problem of Valence Isomerism between 1,2-Dithiine and (Z)-But-2-ene-1,4-dithione

1988 ◽  
Vol 43 (5) ◽  
pp. 605-610 ◽  
Author(s):  
Reiner Radeglia ◽  
Helmut Poleschner ◽  
Werner Schroth
Keyword(s):  
Nmr Spectra ◽  
Chemical Shifts ◽  
2D Nmr ◽  
Ring Structure ◽  
Coupling Constants ◽  
Nmr Parameters ◽  
Spectrum Simulation ◽  
2D Nmr Spectra ◽  
Transoid Conformation ◽  
C Nmr

3,6-Diaryl-1,2-dithiines and their precursors, (Z,Z)-1,4-bis(organylthio)-buta-1,3-dienes, are investigated by 1H and 13C NMR spectroscopy. The chemical shifts and coupling constants, which are relevant to the investigated problem, are determined and assigned, respectively, by different techniques (shift increments, spectrum simulation, heteronuclear 2D J-resolved and heteronuclear shift correlated 2D NMR spectra, anomalous off-resonance splittings and selective decoupling experiments). The NMR parameters are discussed in relation to the molecular structure. The 13C shift values prove the ring structure of 1,2-dithiines and exclude existence of the valence isomer (Z)-but-2-ene-1,4-dithione (absence of thiocarbonyl resonances). The vicinal 1H,1H coupling constants of the C4 unit of the investigated compounds verify (1) the (Z,Z) configuration of the organylthio groups in 1,4 position of butadiene, (2) the s-transoid conformation of acyclic butadienes and (3) the forced s-cis structure in the cyclic 1,2-dithiines.

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.

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.

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