ChemInform Abstract: Syntheses of Bile Pigments. Part 15. First Unequivocal Assignment of the Absolute Configuration of an Urobilinoid Bile Pigment by X-Ray Diffraction Analysis of Its Synthetic Precursor.

ChemInform ◽  
1988 ◽  
Vol 19 (11) ◽  
Author(s):  
C. PASQUIER ◽  
A. GOSSAUER ◽  
W. KELLER ◽  
C. KRATKY
Keyword(s):  
Diffraction Analysis ◽  
Absolute Configuration ◽  
Bile Pigment ◽  
Bile Pigments ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Absolute

scholarly journals Diastereoselective Addition of Diazomethane to Zaluzanin A

2014 ◽  
Vol 9 (6) ◽  
pp. 1934578X1400900 ◽  
Author(s):  
Adriana Ortiz-León ◽  
J. Martín Torres-Valencia ◽  
J. Jesús Manríquez-Torres ◽  
José G. Alvarado-Rodríguez ◽  
Uvaldo Hernández-Balderas ◽  
...  
Keyword(s):  
Diffraction Analysis ◽  
Absolute Configuration ◽  
Sesquiterpene Lactones ◽  
Addition Product ◽  
Vibrational Circular Dichroism ◽  
X Ray Diffraction ◽  
X Ray ◽  
H Nmr ◽  
Diastereoselective Addition ◽  
The Absolute

The diastereoselectivity of diazomethane addition to the conjugated double bond of α,β-unsaturated sesquiterpene lactones was explored using zaluzanin A (1) as a model. Thus, the absolute configuration of 1 was assured by X-ray diffraction analysis including evaluation of Flack and Hooft parameters, and by vibrational circular dichroism spectroscopy of its diacetyl derivative 2, while the absolute configuration of the diazomethane addition product, zaluzanin A pyrazoline (3), was determined by evaluation of the 1H NMR chemical shift changes with respect to 1, and confirmed by X-ray diffraction analysis, again including evaluation of Flack and Hooft parameters.

scholarly journals Determination of the absolute configuration of (+)-neopentyl-1-d alcohol by neutron and x-ray diffraction analysis.

1994 ◽  
Vol 91 (26) ◽  
pp. 12872-12876 ◽  
Author(s):  
H. S. Yuan ◽  
R. C. Stevens ◽  
R. Bau ◽  
H. S. Mosher ◽  
T. F. Koetzle
Keyword(s):  
Diffraction Analysis ◽  
Absolute Configuration ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Absolute

Confirmation of the absolute configuration of Stachybotrin C using single-crystal X-ray diffraction analysis of its 4-bromobenzyl ether derivative

2018 ◽  
Vol 71 (6) ◽  
pp. 584-591 ◽  
Author(s):  
Yu Kuroda ◽  
Keiko Hasegawa ◽  
Keiichi Noguchi ◽  
Kazuhiro Chiba ◽  
Keiji Hasumi ◽  
...  
Keyword(s):  
Single Crystal ◽  
Diffraction Analysis ◽  
Absolute Configuration ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ether Derivative ◽  
The Absolute

Alkaloids of Rauvolfia salicifolia GRISEB species

1982 ◽  
Vol 47 (11) ◽  
pp. 2912-2921 ◽  
Author(s):  
Patricia Sierra ◽  
Ladislav Novotný ◽  
Zdeněk Samek ◽  
Miloš Buděšínský ◽  
Ladislav Dolejš ◽  
...  
Keyword(s):  
Absolute Configuration ◽  
Cd Spectroscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Absolute

From the endemic Cuban species Rauvolfia salicifolia GRISEB nine alkaloids were isolated of which the following seven had been already described: (+)-ajmalidine (I), (-)-reserpiline (II), (-)-isoreserpiline (III), (-)-isocarapanaubine (IV), (-)-ajmalicine (V), (+)-vellosimine (VI), and (+)-yohimbine (VII). The structure of (-)-raucubaine (VIII) had been previously determined by X-ray diffraction and the structure of the alkaloid (-)-raucubainine (IX) was suggested on the basis of its conversion to (-)-raucubaine (VIII). The absolute configuration of (-)-raucubaine and (-)-raucubainine was elucidated by CD spectroscopy.

scholarly journals Absolute Configuration of Cembrane Diterpenoids from Bursera multijuga

2014 ◽  
Vol 9 (9) ◽  
pp. 1934578X1400900 ◽  
Author(s):  
Juan D. Hernández-Hernández ◽  
Hugo A. García-Gutiérrez ◽  
Luisa U. Román-Marín ◽  
Yunuen I. Torres-Blanco ◽  
Carlos M. Cerda-García-Rojas ◽  
...  
Keyword(s):  
Molecular Modeling ◽  
Absolute Configuration ◽  
2D Nmr ◽  
Vibrational Circular Dichroism ◽  
Conformational Preference ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Absolute ◽  
First Time ◽  
Good Agreement

The stems of Bursera multijuga afforded (-)-(1 S,3 E,7 R,8 R,11 E)-7,8-epoxycembra-3,11-dien-1-ol (1) and its acetate 2, together with cembrene A (3), nephthenol (4), and cembrenol (5). The structures of 1 and 2 were elucidated by 1D and 2D NMR, HRESIMS, and X-ray diffraction. The conformational preference of flexible 1 was studied by molecular modeling at the DFT B3LYP/DGDZVP level of theory. Good agreement between calculated and experimental vibrational circular dichroism curves established the absolute configuration of 1. This is the first time that cembrane derivatives have been isolated from the genus Bursera.

scholarly journals A Pair of New Polyketide Enantiomers from Three Endolichenic Fungal Strains Nigrospora sphaerica, Alternaria alternata, and Phialophora sp

2016 ◽  
Vol 11 (6) ◽  
pp. 1934578X1601100 ◽  
Author(s):  
Jun-Wei He ◽  
Chuan-Xi Wang ◽  
Li Yang ◽  
Guo-Dong Chen ◽  
Dan Hu ◽  
...  
Keyword(s):  
Diffraction Analysis ◽  
Alternaria Alternata ◽  
Spectroscopic Methods ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fungal Strains ◽  
The Absolute ◽  
Modified Mosher’S Method

A pair of new enantiomeric polyketides, (-)- and (+)-nigrosporaol A (1a and 1b), along with one related known compound, (±)-alternarienoic acid (2), were isolated from three endolichenic fungal strains, Nigrospora sphaerica (No.83-1-1-2), Alternaria alternata (No.58-8-4-1), and Phialophora sp.(No.96-1-8-1). Their structures, including the absolute configurations, were elucidated on the basis of spectroscopic methods, X-ray diffraction analysis, and the modified Mosher's method.

Structure of isosilerolide, relative and absolute configuration of silerolide and lasolide - Sesquiterpenic lactones of new stereoisomeric type of eudesmanolides

1986 ◽  
Vol 51 (4) ◽  
pp. 903-929 ◽  
Author(s):  
Miroslav Holub ◽  
Miloš Buděšínský ◽  
Zdenka Smítalová ◽  
David Šaman ◽  
Urszula Rychłewska
Keyword(s):  
Absolute Configuration ◽  
X Ray Diffraction ◽  
X Ray ◽  
H Nmr ◽  
Nmr Data ◽  
Chemical Correlation ◽  
The Absolute

On the basis of spectroscopic, particularly 1H NMR data, isosilerolide was assigned structure I, including the absolute configuration. The structure was confirmed by X-ray diffraction. Isosilerolide represents a new stereoisomeric type of natural eudesmanolides, characterized as 5βH, 6αH, 7αH, 10αCH3-eudesman-6,12-olide. As shown by the chemical correlation of isosilerolide (I) with silerolide (III) and lasolide (X), the latter two natural lactones belong to this stereoisomeric group of eudesmanolides. Analysis of models and 1H NMR data shows that structures of some eudesman-6,12-olides, published by other authors, should be corrected.

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