Étude conformationnelle de cétopipérazines: (I) 3R-méthyl-6-carbéthoxy-2 oxopipérazine, (II) 3R-[p-hydroxybenzyl]-6-carbéthoxy-2 oxopipérazine: I, II en solution et structure cristalline de II

1987 ◽  
Vol 65 (6) ◽  
pp. 1308-1312 ◽  
Author(s):  
André Michel ◽  
Guy Evrard ◽  
B. Norberg
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Absolute Configuration ◽  
Structure Determination ◽  
Opiate Receptor ◽  
Receptor Level ◽  
X Ray ◽  
Diastereomeric Mixture ◽  
The Absolute

The synthesis of the title compounds has been described recently. It was anticipated that the product would be a diastereomeric mixture. Surprisingly, only one isomer was obtained. The present work is an attempt to find the conformationnal properties accounting for those observations. X-ray structure determination of 3R-[p-hydroxybenzyl]-6-carbethoxy-2-oxopiperazine shows that the molecule adopts a folded conformation and that the absolute configuration at C6 is [R]. Investigation in solution using 1H nuclear magnetic resonance shows the existence of three conformers and discusses the relative populations. Those findings are also relevant in terms of the activity of such compounds at the opiate receptor level.

DETERMINATION OF THE ABSOLUTE CONFIGURATION OF NEW PIPERIDIN-4-ONE DERIVATIVE FROM Pellacalyx saccardianus BY NOESY SPECTROSCOPY

2016 ◽  
Vol 78 (3-2) ◽  
Author(s):  
Salam Ahmed Abed ◽  
Hasnah Mohd Sirat
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
Absolute Configuration ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Absolute ◽  
Nuclear Overhauser ◽  
Nuclear Magnetic

A new alkaloid, pellacalyxin was isolated from the leaves of Pellacalyx saccardianus of Rhizophoraceae family. Pellacalyxin was analyzed using nuclear Overhauser spectroscopy (NOESY) nuclear magnetic resonance (NMR) technique to determine the absolute configuration. The analysis of absolute configuration of pellacalyxin was supported by X-ray crystallography. 1H-1H NOESY NMR spectroscopy exhibited that pellacalyxin possesses two chiral centers (3S) and (6R).

Metabolites of bird's nest fungi. Part 4. The isolation and structure determination of cybullol, a metabolite of Cyathus bulleri Brodie

1976 ◽  
Vol 54 (6) ◽  
pp. 910-916 ◽  
Author(s):  
William A. Ayer ◽  
Michael G. Paice
Keyword(s):  
Magnetic Resonance ◽  
Absolute Configuration ◽  
Structure Determination ◽  
Mass Spectra ◽  
Fungal Metabolite ◽  
Physical Methods ◽  
The Absolute ◽  
Circular Dichroïsm ◽  
Magnetic Resonance Spectra

Cybullol, a metabolite of Cyathus bulleri Brodie, has been shown to be (2S,5S,6S,10S)-cis-6, trans-10-dimethyl-r-2-cis-5-decalindiol (1) by a combination of chemical and physical methods. The mass spectra and the 1H and 13C magnetic resonance spectra of cybullol and derivatives are discussed. The absolute configuration of cybullol was deduced from the circular dichroism spectrum of the ketol 3. Cybullol has been transformed into the fungal metabolite (−)-geosmin (11). This correlation establishes the absolute configuration of (−)-geosmin.

Metabolites of Lachnellula fuscosanguinea (Rehm). Part 2. The structure of lachnellulone

1988 ◽  
Vol 66 (3) ◽  
pp. 506-512 ◽  
Author(s):  
William A. Ayer ◽  
J. Daniel Figueroa Villar ◽  
Barbara S. Migaj
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Absolute Configuration ◽  
Mass Spectra ◽  
Antifungal Metabolite ◽  
X Ray ◽  
Crystallographic Study ◽  
Nuclear Magnetic Resonance Spectra ◽  
The Absolute ◽  
Nuclear Magnetic

Lachnellulone, an antifungal metabolite produced by Lachnellula fuscosanguinea (Rehm) Dennis is shown to possess structure 8. The structure was determined by consideration of the ultraviolet, infrared, 1H and 13C nuclear magnetic resonance, and mass spectra of 8 and its derivatives and was confirmed by an X-ray crystallographic study of lachnellulone p-nitrobenzoate. In solution lachnellulone undergoes facile isomerization to isolachnellulone (9a), which explains the observed mutarotation of 8. The 13C nuclear magnetic resonance spectra of lachnellulone and the related lachnelluloic acid (1) are discussed in some detail. The absolute configuration of lachnellulone has not been determined.

The Chemistry of Eremophila Spp. XXIX. The Absolute Configuration of (+)-Syringaresinol Dimethyl Ether

1987 ◽  
Vol 40 (11) ◽  
pp. 1913 ◽  
Author(s):  
IR Bytheway ◽  
EL Ghisalberti ◽  
S Gotsis ◽  
PR Jefferies ◽  
BW Skelton ◽  
...  
Keyword(s):  
Absolute Configuration ◽  
Structure Determination ◽  
Title Compound ◽  
Room Temperature ◽  
Orthorhombic Space Group ◽  
Full Matrix ◽  
X Ray ◽  
The Absolute ◽  
Dibromo Derivative

The absolute configuration of the title compound has been established from a single-crystal room temperature X-ray structure determination of its dibromo derivative, C24H28Br2O8. Crystals of the latter are orthorhombic, space group P21212, a l6.696(5), b l5.660(3), c 4.713(1) �, Z 2; 1452 independent 'observed' reflections yielded R 0.033 following full-matrix least-squares refinement. The molecule lies on a crystallographic 2 axis. The occurrence of lignans in Eremophila species is summarized.

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