ChemInform Abstract: CARBON-13 NMR SPECTRA OF ALLYLIC BORON “ATE” COMPLEXES. RELATIVE IMPORTANCE OF .SIGMA±PI. CONJUGATION BETWEEN THE DOUBLE BOND AND THE CARBON-BORON BOND

1981 ◽  
Vol 12 (1) ◽  
Author(s):  
Y. YAMAMOTO ◽  
H. YATAGAI ◽  
Y. NARUTA ◽  
K. MARUYAMA ◽  
T. OKAMOTO
Keyword(s):  
Double Bond ◽  
Nmr Spectra ◽  
Relative Importance ◽  
Pi Conjugation

13C NMR spectra of allylic boron “ate” complexes. Relative importance of σ-π conjugation between the double bond and the carbon-boron bond

1980 ◽  
Vol 21 (37) ◽  
pp. 3599-3602 ◽  
Author(s):  
Yoshinori Yamamoto ◽  
Hidetaka Yatagai ◽  
Yoshinori Naruta ◽  
Kazuhiro Maruyama ◽  
Tadashi Okamoto
Keyword(s):  
Double Bond ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Relative Importance ◽  
13C Nmr Spectra

Some Considerations Regarding the 1H and 13C Spectra of 4-(1-azulenyl)-2,6-bis(2-heteroaryl-vinyl)- pyrylium and Pyridinium and their Corresponding Pyridines

2018 ◽  
Vol 69 (1) ◽  
pp. 64-69
Author(s):  
Liviu Birzan ◽  
Mihaela Cristea ◽  
Constantin C. Draghici ◽  
Alexandru C. Razus
Keyword(s):  
Double Bond ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Pyridinium Salts ◽  
13C Nmr Spectra ◽  
1H And 13C Nmr ◽  
Pyrylium Salts

The 1H and 13C NMR spectra of several 2,6-diheteroarylvinyl heterocycles containing 4-azulenyl moiety were recorded and their proton and carbon chemical shifts were compared with those of the compounds without double bond between the heterocycles. The influence of the nature of central and side heterocycles, molecule polarization and anisotropic effects were revealed. The highest chemical shifts were recorded for the pyrylium salts and the lowest at pyridines, but in the case of the pyridinium salts, the protons chemical shifts at the central heterocycle are more shielded due to a peculiar anisotropy of the attached vinyl groups.

15N, 13C, and 1H NMR Spectra of Azo and Hydrazo Compounds Derived from 1,3,3-Trimethyl-2-methylidene-2,3-dihydroindole (Fischer Base)

1998 ◽  
Vol 63 (7) ◽  
pp. 1012-1020 ◽  
Author(s):  
Antonín Lyčka ◽  
Josef Jirman ◽  
Alois Koloničný
Keyword(s):  
Double Bond ◽  
Hydrochloric Acid ◽  
Nmr Spectra ◽  
Coupling Constants ◽  
Azo Compounds ◽  
Passive Component ◽  
Geometric Isomers ◽  
H Nmr ◽  
Fischer Base ◽  
Hydrazone Form

The 15N, 13C, and 1H NMR spectra were measured for azo and hydrazo compounds derived from 1,3,3-trimethyl-2-methylidene-2,3-dihydroindole (Fischer base), which is a passive component with a terminal methylidene group. Products prepared by coupling in hydrochloric acid exist in the corresponding hydrazone form as the E-isomers. Neutralization gives a mixture of two isomeric azo compounds which differ in the arrangement at the C(2)=C(10) double bond. This mixture was alkylated with methyl iodide to obtain the =N-N(CH3)- hydrazone derivatives. The geometric isomers were resolved based on the NOESY approach and the stereospecific behaviour of the 2J(15N,13C) coupling constants was studied for the 15N-labelled compounds.

Preparation of New Oxidized 18-α-Oleanane Derivatives

2005 ◽  
Vol 70 (9) ◽  
pp. 1447-1464 ◽  
Author(s):  
Miroslav Kvasnica ◽  
Iva Tišlerová ◽  
Jan Šarek ◽  
Jan Sejbal ◽  
Ivana Císařová
Keyword(s):  
Double Bond ◽  
Nmr Spectra ◽  
Biological Activities ◽  
Oxidative Cleavage ◽  
Allylic Oxidation ◽  
Unsaturated Ketone ◽  
Ruthenium Tetroxide ◽  
Unsaturated Compounds ◽  
Starting Compound ◽  
C Nmr

19β,28-Epoxy-4,5-seco-3,5-cyclo-18α-olean-3(5)-ene (2) is an appropriate compound for oxidations, which lead to new oxidized compounds with potential biological activities. Several oxidations were used such as epoxidation, allylic oxidation, oxidative cleavage of double bond and other ones. From the starting compound epoxides 3a, 3b and unsaturated ketone 4 were prepared. This ketone was further oxidized to diketone 6 and anhydride 7. The double bonds of all unsaturated compounds were cleaved with ruthenium tetroxide to afford new A-seco oleananes. The structure and stereochemistry of the compounds were derived from IR, MS, 1H and 13C NMR spectra (1D and 2D COSY, TOCSY, NOESY, HSQC, HMBC).

Preparation and Conformational Study of B-Ring Substituted Lupane Derivatives

2006 ◽  
Vol 71 (8) ◽  
pp. 1131-1160 ◽  
Author(s):  
Martin Dračínský ◽  
Simona Hybelbauerová ◽  
Jan Sejbal ◽  
Miloš Buděšínský
Keyword(s):  
Double Bond ◽  
Hydroxy Group ◽  
Molecular Modelling ◽  
Nmr Spectra ◽  
Hydroxy Derivative ◽  
Secondary Hydroxy Group ◽  
Conformational Study ◽  
Primary Hydroxy Group ◽  
Type 3 ◽  
C Nmr

New lupane-type triterpenoids with 5(6) double bond were prepared using the method of partial demethylation on carbon C-4. Hydroboration of the double bond led to 6α-hydroxy derivative. By the oxidation and following reduction of 6α-hydroxy derivative the 6-oxo and 6β-hydroxy derivatives were prepared. A new method for selective oxidation of secondary hydroxy group in the presence of primary hydroxy group was performed. The conformation of ring A of new lupane-type 3-oxo derivatives with a substituent on ring B was elucidated on the bases of 1H and 13C NMR spectra and molecular modelling.

Hétérobicycles oxygénés. Synthèse d'alkyl-3,6,8-trioxabicyclo[3.2.1]octanes et d'alkyl-3,7,9 et -4,7,9-trioxabicyclo[4.2.1]nonanes

1978 ◽  
Vol 56 (17) ◽  
pp. 2292-2300 ◽  
Author(s):  
Pierre Calinaud ◽  
Jacques Gelas
Keyword(s):  
Double Bond ◽  
Carbon Atom ◽  
Nmr Spectra ◽  
Membered Ring ◽  
Coupling Constants ◽  
Basic Medium ◽  
Main Interest ◽  
Proton Coupling ◽  
Geminal Proton

The cyclization in a basic medium of 2 (or 4)-chloroalkyl-4 (or 2) -hydroxyalkyl-1,3-dioxolanes leads to bicyclic acetals, the 3,6,8-trioxabicyclo[3.2.1]octanes, which are useful intermediates for synthesis, yielding notably functionalized 1,4-dioxanes. The nmr spectra of these heterobicyclics were studied. The geminal proton coupling constants permit oneto distinguish between five- and six-membered rings and the determination of couplings over several bonds (4J and 5J) yields information concerning the conformation of the model bicyclics.Two isomeric series of alkylated bicyclic acetals (3,7,9- and 4,7,9-trioxabicyclo[4.2.1]nonanes) are accessible by the following routes: (a) the intramolecular addition of a 4-hydroxy-alkyl group to the ethylenic double bond on the carbon atom a to C-2 in the 1,3-dioxolanes; (b) the dechlorohydration of 2-chloromethyl-4-hydroxyalkyl-1,3-dioxolanes; (c) the dehydration of dioxolane-diols. The main interest in these heterobicyclics is to prepare a seven-membered ring and to be able to prepare functionalized 1,4-dioxepanes. [Journal translation]

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.

Anhydrobetulin and its derivatives

1991 ◽  
Vol 56 (4) ◽  
pp. 886-904 ◽  
Author(s):  
Alois Vystrčil ◽  
Václav Křeček ◽  
Jiří Protiva ◽  
Miloš Buděšínský
Keyword(s):  
Double Bond ◽  
Alkaline Medium ◽  
Sodium Borohydride ◽  
Mass Spectra ◽  
Nmr Spectra ◽  
Cotton Effect ◽  
Addition Reactions ◽  
Chemical Transformations ◽  
C Nmr ◽  
Reduction Of Ketones

The structure of anhydrobetulin II and its derivatives I, III and IV has been solved using 1H and 13C NMR spectra, mass spectra and chemical transformations. It has been proven that in addition reactions the trisubstituted double bond is attacked selectively from the α-side under formation of D/E cis-annelated derivatives VIII, X and XI. The 22-oxo derivative XIII exhibits an anomalous Cotton effect and, in contrast to its saturated analogue XXVII,it is not epimerized in alkaline medium. Trinordiketone XXI easily epimerizes to a mixture in which the 17βH-epimer XXIb predominates, trinorketone XXIV is stable only if the annelation of rings D and E is trans. These differences are explained in terms of steric interactions of substituents in position 19. The steric course of reduction of ketones XIII and XXIV with sodium borohydride is described.

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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