1H and 13C NMR study of some substituted 2-furyl- and 2-thienylethylene derivatives

1986 ◽  
Vol 51 (4) ◽  
pp. 889-898 ◽  
Author(s):  
Miloslava Dandárová ◽  
Daniel Végh ◽  
Jaroslav Kováč ◽  
Igor Goljer ◽  
Nadežda Prónayová ◽  
...  
Keyword(s):  
Double Bond ◽  
Heterocyclic Ring ◽  
Coupling Constants ◽  
Side Chain ◽  
1H And 13C Nmr ◽  
H Nmr ◽  
Nmr Data ◽  
Nmr Study ◽  
Thiophene Derivatives ◽  
C Nmr

The 1H and 13C NMR spectral data of 1-(5-nitro-2-furyl)-2-X-2-Y-ethylenes and some their thienyl analogues are presented. Geometrical arrangement of the trisubstituted ethylenes was adduced from vicinal coupling constants 3J(C, H) for the carbon atom at the functional group attached to the double bond and the ethylene proton. The orientation of the heterocyclic ring towards the double bond of the side chain was determined from the 1H NMR data. The preferred s-cis or s-trans conformations of 5-nitro-2-furylethylene derivatives is substituent at the double bond dependent; all thiophene derivatives under study were found in the s-trans conformation.

Stereochemistry of some substituted 2-furyl- and 2-thienyl ethylene derivatives. 1H NMR study

1982 ◽  
Vol 47 (12) ◽  
pp. 3412-3417 ◽  
Author(s):  
Miloslava Dandárová ◽  
Jaroslav Kováč ◽  
Daniel Végh ◽  
Vladimír Žvak
Keyword(s):  
Double Bond ◽  
Nmr Spectroscopy ◽  
1H Nmr ◽  
Side Chain ◽  
H Nmr ◽  
Nmr Study ◽  
Thiophene Derivatives

Stereochemistry of (E)- and (Z)-1-(5-nitro-2-furyl)-2-Y-ethylenes and 1-(5-nitro-2-thienyl)-2-Y-ethylenes (where Y = CH3O, 4-CH3C6H4O, N3 and Br) and of E and Z isomers of methyl 2-methyl-3-(2-furyl)propenoate and methyl 2-methyl-3-(2-thienyl)propenoate was studied by 1H NMR spectroscopy. With 1-(5-nitro-2-furyl)-2-Y-ethylenes, it was found that the preferred conformation of the furyl substituent relative to the side chain double bond is s-trans in the E isomers and s-cis in the Z isomers. The s-cis conformation is prevailing in both isomers of methyl 2-methyl-3-(2-furyl)propenoate. The E and Z isomers of all studied thiophene derivatives exist in the s-trans conformation.

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.

1H and 13C NMR Study of Proton Transfer in Azoles. Mechanism of Proton Transfer in Pyrazole in Solutions Containing bis-(Acetylacetonato) Nickel (II)

1976 ◽  
Vol 31 (7-8) ◽  
pp. 353-360 ◽  
Author(s):  
V. N. Babin ◽  
E. B. Zavelovidi ◽  
E. I. Fedin
Keyword(s):  
Proton Transfer ◽  
Ligand Exchange ◽  
Hyperfine Coupling ◽  
Outer Sphere ◽  
Coupling Constants ◽  
1H And 13C Nmr ◽  
Nmr Study ◽  
Nmr Techniques ◽  
Kinetics Of ◽  
C Nmr

Abstract Proton Transfer, Pyrazole, Outer-Sphere Coordination Proton transfer in pyrazole systems involving interaction with a paramagnetic transition metal complex has been studied with 1H and 13C NMR techniques. Kinetics of the ligand exchange in the pyrazole complex of bis-(acetylacetonato) nickel (II) has been investigated, and hyperfine coupling constants for the interaction of the nickel unpaired electron with the ligand nuclei in the complex have been determined. Catalytic admixtures of bis-(acetylacetonato) nickel (II) are shown to modify the mechanism of the proton transfer in pyrazole. The spectral data are discussed in terms of outer-sphere coordination and cooperative proton transfer effects.

Analysis of 1H-NMR spectra of cinnamaldehyde type model substances of lignin

1980 ◽  
Vol 45 (2) ◽  
pp. 330-334 ◽  
Author(s):  
Tibor Liptaj ◽  
Milan Remko ◽  
Ján Polčin
Keyword(s):  
Double Bond ◽  
Nmr Spectra ◽  
Side Chain ◽  
Type Model ◽  
Stable Conformer ◽  
Spectra Analysis ◽  
H Nmr ◽  
Nmr Data ◽  
Lignin Model ◽  
Model Substances

1H-NMR spectra of the following lignin model substances have been analyzed: cinnamaldehyde, 2-methoxycinnamaldehyde, 3-methoxycinnamaldehyde, 4-methoxycinnamaldehyde, 3,4-dimethoxycinnamaldehyde, 3-methoxy-4-hydroxycinnamaldehyde and 3,4,5-trimethoxycinnamaldehyde. From the NMR spectra analysis it follows that the studied compounds exist in solutions as trans isomers. Theoretical (PCILO) calculations in agreement with the NMR data have shown that the more stable conformer has trans orientation of C=O group with respect to the double bond of the conjugated side chain.

A contribution to peroxy acid oxidation of α,β-unsaturated ketones and linearly conjugated dienones: Reactions in the cholestane series

1988 ◽  
Vol 53 (7) ◽  
pp. 1549-1567 ◽  
Author(s):  
Václav Černý ◽  
Miloš Buděšínský ◽  
Miloš Ryba ◽  
František Tureček
Keyword(s):  
Double Bond ◽  
Carbonyl Group ◽  
Acid Oxidation ◽  
Peroxy Acid ◽  
Unsaturated Ketones ◽  
H Nmr ◽  
Nmr Data ◽  
Epoxy Ketones ◽  
C Nmr

Oxidation with 3-chloroperoxybenzoic acid of s-cis α,β-unsaturated ketones IX, XI and s-trans types X, XII was compared. The s-cis ketones show higher reactivity and furnish a higher yield of the corresponding α,β-epoxy ketones than the s-trans ketones. Products of the Baeyer-Villiger reaction are formed only in low yield. The dienone VI is oxidized predominantly to VII thus violating the rule that linear conjugated dienones are epoxidized at the double bond more distant from the carbonyl group; this result is in accord with the behaviour of s-cis α,β-unsaturated ketones. 1H NMR and 13C NMR data of the starting compounds and of the products are reported.

Steroids with the β-crotonate (2-butenoate) side chain

1986 ◽  
Vol 51 (1) ◽  
pp. 128-140 ◽  
Author(s):  
Ivan Černý ◽  
Vladimír Pouzar ◽  
Pavel Drašar ◽  
František Tureček ◽  
Miroslav Havel
Keyword(s):  
Double Bond ◽  
Nmr Spectroscopy ◽  
Lithium Salt ◽  
Side Chain ◽  
H Nmr ◽  
C Nmr

Ethyl (20E)-3β-methoxymethoxy-24-nor-5,20(22)-choladien-23-oate (Va) and analogous derivatives with 5α,5β and Δ5,14 steroid moiety (Vb,Vc and Vd, respectively) were prepared by Wittig-Horner reaction of the corresponding ketones IIa-IId with diethyl ethoxycarbonylmethylphosphonate. In this case the reaction affords exclusively the (E)-isomers, in contrast with the Peterson reaction with lithium salt of ethyl 2-(trimethylsilyl)acetate which gives a mixture of (E)- and (Z)-isomers at the Δ20(22) double bond. The structure of the products was confirmed by 1H NMR and 13C NMR spectroscopy. The crotonates Va-Vd were further converted into the 3-O-succinyl derivatives VIIIa-VIIId.

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.

1H and 13C NMR study of the pyrazolo[1,5-a]pyrimidine system

1992 ◽  
Vol 70 (4) ◽  
pp. 1093-1097 ◽  
Author(s):  
Stefano Chimichi ◽  
Barbara Cosimelli ◽  
Fabrizio Bruni ◽  
Silvia Selleri
Keyword(s):  
Coupling Constants ◽  
Pyrimidine Derivatives ◽  
Simple Method ◽  
Nmr Spectrum ◽  
1H And 13C Nmr ◽  
Methyl Group ◽  
H Nmr ◽  
Nmr Study ◽  
Methyl Derivatives ◽  
Carbon Chemical Shift

The 13C and 1H NMR spectra of some pyrazolo[1,5-a]pyrimidine derivatives are discussed. All 13C resonances were unambiguously assigned by means of both 2D experiments and gated decoupled spectra from which one-bond and long-range 13C–1H coupling constants were determined. The literature assignments for H-5 and H-7 in the parent system have been revised and a simple method for distinguishing between 5-methyl and 7-methyl compounds is suggested, based on the carbon chemical shift of the methyl group or on its fine structure in the 1H NMR spectrum. Regioselective syntheses for all the reported methyl derivatives are also described.

Identification of acyl groups occurring in sesquiterpene lactones: Proton and carbon-13 NMR study

1987 ◽  
Vol 52 (2) ◽  
pp. 453-475 ◽  
Author(s):  
Miloš Buděšínský ◽  
David Šaman
Keyword(s):  
Chemical Shifts ◽  
Sesquiterpene Lactones ◽  
Nmr Chemical Shifts ◽  
H Nmr ◽  
Nmr Parameters ◽  
Nmr Data ◽  
Nmr Study ◽  
C Nmr

Characteristic 1H NMR parameters of 88 acyl groups, hitherto found as ester substituents in natural sesquiterpenic lactones, were determined from the measured spectra as well as literature data. Characteristic 13C NMR chemical shifts for 45 acyl groups were obtained in the same way; for the remaining acyls with hitherto unknown 13C NMR data the values were calculated on the basis of semiempirical relationships.

1H and 13C NMR study of (X-phenyl)-5-nitro-2-furylvinyl ethers

1980 ◽  
Vol 45 (12) ◽  
pp. 3557-3563 ◽  
Author(s):  
Miloslava Dandárová ◽  
Jaroslav Kováč ◽  
Daniel Végh
Keyword(s):  
Nmr Spectroscopy ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Furan Ring ◽  
Chemical Shifts ◽  
1H And 13C Nmr ◽  
H Nmr ◽  
Nmr Study ◽  
Hammett Σ Constants ◽  
C Nmr

Reaction of 5-nitro-2-furylvinyltrimethylammonium bromide with substituted phenolates gave (E)- and (Z)-(X-phenyl)-5-nitro-2-furylvinyl ethers. The preffered s-cis and s-trans orientations of the furan ring in Z and E isomers, respectively, were determined by 1H NMR spectroscopy. To study the extent of p-π conjugation, 13C NMR spectra of compounds under investigation have also been measured and interpreted. Chemical shifts for ethylenic carbons and protons were correlated with Hammett σ constants.

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