Synthesis of 3β,4β-cyclopropano-19-nor-A-homosteroids

1985 ◽  
Vol 50 (7) ◽  
pp. 1611-1617 ◽  
Author(s):  
Jiří Joska ◽  
Jan Fajkoš ◽  
Jaroslav Zajíček
Keyword(s):  
Double Bond ◽  
Metal Hydride ◽  
Nmr Spectra ◽  
H Nmr ◽  
Hydride Reduction ◽  
Sole Product

Acetolysis of the tosylate XIII, afforded the olefin XIV as the sole product. Epoxidation of the double bond gave the epoxide XV which on metal hydride reduction yielded the alcohol XVI. The structures of these products were established by spectral and chemical means and conformation of the A-homo ring in the epoxide XV is discussed on the basis of the 1H NMR spectra.

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.

Study of the Reactivity of 2-Benzylidene[3]ferrocenophane-1,3-dione with Ethyl Acetoacetate and Some Other C-Nucleophiles

1993 ◽  
Vol 58 (9) ◽  
pp. 2128-2138
Author(s):  
Marta Sališová ◽  
Ľubomír Šebo ◽  
Štefan Toma ◽  
Eva Solčániová
Keyword(s):  
Intramolecular Cyclization ◽  
Michael Addition ◽  
Ethyl Acetoacetate ◽  
Nmr Spectra ◽  
H Nmr ◽  
Michael Adducts ◽  
Pyran Derivative ◽  
Dihydropyridine Derivatives ◽  
Sole Product

Michael addition of C-nucleophiles to 2-benzylidine[3]ferrocenophane-1,3-dione has been studied. In some cases, (ethyl acetoacetate, acetylacetone and malononitrile as the C-nucleophiles) the addition was followed by intramolecular cyclization leading to pyran derivatives. Addition of malononitrile gave the pyran derivative as a sole product. The Michael adducts of ethyl acetoacetate and acetylacetone can be converted to [7]ferrocenophane-1,7-dione derivatives by refluxing in benzene with triethylamine as catalyst. they also easily react with ammonia, under SiO2 catalysis, to give Hantzsch dihydropyridine derivatives. The 1H NMR spectra of the products are discussed.

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.

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.

Synthesis and Photochemical Trasformations of 19-Phenylsulfonyl Provitamin D Analogue

1998 ◽  
Vol 63 (10) ◽  
pp. 1597-1612
Author(s):  
Piotr Grzegorzewski ◽  
Izabela Koladkiewicz ◽  
Jacek W. Morzycki ◽  
Rafal R. Sicinski
Keyword(s):  
Double Bond ◽  
Uv Irradiation ◽  
Efficient Method ◽  
Nmr Spectra ◽  
Complex Mixture ◽  
The Other ◽  
Allylic Oxidation ◽  
H Nmr ◽  
Nucleophilic Displacement ◽  
Displacement Reactions

The synthesis of provitamin D analogue 19-(phenylsulfonyl)androsta-5,7-diene-3β,17β-diyl 3-acetate 17-pivalate (20) has been accomplished from 19-hydroxyandrost-5-ene-3β,17β-diyl 3-acetate 17-pivalate. 19-(Phenylsulfonyl)androst-5-ene-3β,17β-diyl 3-acetate 17-pivalate (10), a precursor of 20, was first obtained in low yield in the nucleophilic displacement reactions of 19-halogenated-5-ene steroids with sodium benzenesulfinate. Then a more efficient method has been used, which involves protection of the double bond as an epoxide. Introduction of the C(7)-C(8) double bond into olefin 10 has been also achieved in two ways. The first involved bromination-dehydrobromination and the other consisted of an allylic oxidation of olefin 10 leading to enone and the Bamford-Stevens reaction of its tosylhydrazone. UV irradiation of 5,7-diene 20 resulted in formation of a complex mixture of products. The structures of five isolated compounds were established on the basis of their 1H NMR spectra and mechanistic rationale.

29Si, 13C and 1H NMR spectra of some trimethylsiloxy- and bis(trimethylsiloxy)butene isomers

1983 ◽  
Vol 48 (11) ◽  
pp. 3097-3103 ◽  
Author(s):  
Jan Schraml ◽  
Ján Šraga ◽  
Pavel Hrnčiar
Keyword(s):  
Double Bond ◽  
Nmr Spectroscopy ◽  
Oxygen Atom ◽  
1H Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
1H Nmr Spectra ◽  
Trimethylsilyl Group ◽  
H Nmr ◽  
Steric Crowding

Three isomers of trimethylsiloxybutene were prepared and identified by 1H NMR spectroscopy to be 2-trimethylsiloxy-1-butene and E and Z 2-trimethylsiloxy-2-butenes. E and Z isomers of 2,3-bis(trimethylsiloxy-2-butene were also prepared. 29Si and 13C chemical shifts in these compounds are interpreted. The shifts indicate that the spatial arrangements in the CH3-C-O-Si(CH3)3 fragment is the same in all the pertinent compounds. Steric crowding forces the trimethylsilyl group to assume conformations in which conjugation between unshared electrons of oxygen atom and the electrons of the double bond is inhibited. As a result, olefinic β carbons are deshielded and the shielding of the silicon is increased.

13C and 1H nuclear magnetic resonance spectroscopy of C-19 and 6β-methyl substituted steroids: long-range shift effects in conformational analysis

1979 ◽  
Vol 57 (1) ◽  
pp. 27-37 ◽  
Author(s):  
Katherine Násfay Scott ◽  
Thomas Harold Mareci
Keyword(s):  
Double Bond ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Preferred Orientation ◽  
Range Shift ◽  
Resonance Spectroscopy ◽  
Relative Stabilities ◽  
H Nmr ◽  
1H Nuclear Magnetic Resonance

13C and 1H nmr spectra were obtained and assigned for nine C-19 substituted cholest-5-enes, three 6β-substituted 19-norcholest-5(10)-enes, and several related steroids. 13C chemical shift effects have previously not been studied in either C-19 substituted steroids or in cholest-5(10)-enes. In the present study, substituent effects on the 13C chemical shifts of the α, β, γ, and δ carbons were evaluated in detail. Although the substituent in C-19 substituted and 6β-methyl substituted steroids is less rigidly oriented with respect to the rest of the molecule than in ring-substituted steroids, similar shift effects were observed. In cholest-5-enes the observed 13C and 1H shift effects and the temperature dependence of the 13C shifts indicate that the preferred orientation of the C-19 substituent is anti to C-1. The relative stabilities of the rotamers can be attributed to the orientation of the C-19 substituent with respect to the double bond. This interpretation is supported by the fact that the preferred orientation of the iodine in 6β-iodomethyl-19-norcholest-5(10)-en-3β-ol has the same spacial relationship with respect to the double bond, i.e., gauche to C-5 and C-7.

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.

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.

Preparation and absolute configuration at C(20) of 21-nor-5α-chol-22-en-24→20-olide derivatives

1981 ◽  
Vol 46 (4) ◽  
pp. 917-925 ◽  
Author(s):  
Vladimír Pouzar ◽  
Miroslav Havel
Keyword(s):  
Absolute Configuration ◽  
Nmr Spectra ◽  
Lithium Salt ◽  
H Nmr ◽  
Chemical Correlation ◽  
Unsaturated Lactones

Reaction of the aldehyde I with the lithium salt of 1-(2-tetrahydropyranyloxy)-2-propyne yielded the compounds II and IV. From the compound II the lactone XII was prepared via the intermediates III and X, the lactone XVIII was prepared from the substance IV via the intermediates V and XVI. The unsaturated lactones XII and XVIII were also prepared by sulfenylation and dehydrosulfenylation of the saturated lactones XIII and XIX. Based on chemical correlation and 1H-NMR spectra analyses of the compounds II and IV, the lactone XII was assigned the 20R-configuration whereas the lactone XVIII was allotted the 20S-configuration.

Sign in / Sign up

Export Citation Format

Share Document