Synthèse stéréosélective de (±) boschnialactone, (±) 7-épiteucriumlactone et (±) 7-épiisoiridomyrmécine. Étude de la stéréochimie par spectroscopie de résonance magnétique nucléaire

1990 ◽  
Vol 68 (4) ◽  
pp. 620-627 ◽  
Author(s):  
B. Hanquet ◽  
B. Tabyaoui ◽  
J.-C. Caille ◽  
M. Farnier ◽  
R. Guilard
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Structural Analysis ◽  
Nucleophilic Addition ◽  
Stereoselective Synthesis ◽  
Magnetic Resonance Data ◽  
Lithium Enolates ◽  
Resonance Data ◽  
Résonance Magnétique ◽  
Stereoselective Syntheses ◽  
C Nmr

The stereoselective syntheses of (±) boschnialactone 1, (±) 7-epiteucriumlactone 2, and (±) 7-epiisoiridomyrmecine 3 are described. Their preparation involved Stetter's reaction followed by nucleophilic addition of lithium enolates of suitable esters. Silylated reagents are used in the lactonisation step and the observed yields are between 63 and 78%. The proposed structural analysis is not in accord with the results of a previous study. The nuclear magnetic resonance data are determined using ID and 2D proton and carbon NMR experiments. Keywords: stereoselective synthesis, boschnialactone, 7-epiteucriumlactone, 7-epiisoiridomyrmecine, 1H and 13C NMR.

Spectroscopic Studies on Pyrazaboles

1978 ◽  
Vol 33 (2) ◽  
pp. 220-223 ◽  
Author(s):  
C. E. May ◽  
K. Niedenzu ◽  
S. Trofimenko
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
Mass Spectra ◽  
Spectroscopic Studies ◽  
Conformational Isomers ◽  
Magnetic Resonance Data ◽  
Resonance Data ◽  
C Nmr

The mass spectra of several pyrazaboles of type 1 where R and/or R′ = C2H5 have been studied. The loss of boron-bonded hydrocarbon moieties under electron impact is the predominant feature of all spectra. Some ultraviolet and nuclear magnetic resonance data on compounds of type 1 have been collected; bulky substituents were observed to lead to conformational isomers that can be detected by 13C NMR spectroscopy

Methods to Determine Phytopharmaceuticals in Tobacco and Tobacco Products. 4th Report: A Procedure to Determine Vamidothion and its Metabolites/Methoden zur Bestimmung von Phytopharmaka in Tabak und Tabakerzeugnissen: IV. Mitteilung: Ein Bestimmungsverfahren fuer Vamidothion und seine Metaboliten

1977 ◽  
Vol 9 (2) ◽  
Author(s):  
A.N. Sagredos ◽  
R. Moser
Keyword(s):  
Mass Spectrometry ◽  
Nuclear Magnetic Resonance ◽  
Acetic Acid ◽  
Magnetic Resonance ◽  
Aluminium Oxide ◽  
Nuclear Magnetic Resonance Data ◽  
Gas Chromatograph ◽  
Tobacco Products ◽  
Magnetic Resonance Data ◽  
Resonance Data

AbstractBased on previous work (7) a method to simultaneously determine vamidothion [I], vamidothion-sulfoxide [II] and vamidothion sulfone [III] in tobacco has been developed. The compounds are extracted with water/acetone/acetic acid from the tobacco, cleansed over an aluminium oxide column and then determined on the gas chromatograph with the specific sulphur detector. Rates of recovery are 70 % - 92 %, the determination level is 0.1 ppm. Mass spectrometry and nuclear magnetic resonance data of vamidothion [I], vamidothion-sulfoxide [ II ] and vamidothion-sulfone [III] are given.

Lignans of western red cedar (Thuja plicata Donn). VI. Dihydroxythujaplicatin methyl ether

1967 ◽  
Vol 45 (3) ◽  
pp. 305-309 ◽  
Author(s):  
Harold MacLean ◽  
Koji Murakami
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Methyl Ether ◽  
Degradation Products ◽  
Parent Compound ◽  
Thuja Plicata ◽  
Red Cedar ◽  
Magnetic Resonance Data ◽  
Resonance Data ◽  
Thuja Plicata Donn

Proof of structure is presented for another lignan of the thujaplicatin series, 2,3-dihydroxy-2-(4″-hydroxy-3″,5″-dimethoxybenzyl)-3-(4′-hydroxy-3′-methoxybenzyl)-butyrolactone (I) (dihydroxythujaplicatin methyl ether). Analytical and spectral (ultraviolet, infrared, and nuclear magnetic resonance) data on derivatives and degradation products, in addition to the parent compound, are presented.

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