scholarly journals Determination of the absolute stereostructure of a cyclic azobenzene from the crystal structure of the precursor containing a heavy element

2016 ◽  
Vol 12 ◽  
pp. 2211-2215 ◽  
Author(s):  
Reji Thomas ◽  
Nobuyuki Tamaoki
Keyword(s):  
Cd Spectroscopy ◽  
Chiral Molecules ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heavy Atoms ◽  
Unambiguous Determination ◽  
The Common ◽  
The Absolute ◽  
Reverse Method

Single crystal X-ray diffraction has been used as one of the common methods for the unambiguous determination of the absolute stereostructure of chiral molecules. However, this method is limited to molecules containing heavy atoms or to molecules with the possibility of functionalization with heavy elements or chiral internal references. Herein, we report the determination of the absolute stereostructure of the enantiomers of molecule (E)-2, which lacks the possibility of functionalization, using a reverse method, i.e., defunctionalization of its precursor of known stereostructure with bromine substitution (S-(−)-(E)-1). A reductive debromination of S-(−)-(E)-1 results in formation of one of the enantiomers of (E)-2. Using a combination of HPLC and CD spectroscopy we could safely assign the stereostructure of one of the enantiomers of (E)-2, the reduced product R-(−)-(E)-1.

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.

Unambiguous determination of molecular packing in crystalline donor domains of small molecule solution processed solar cell devices using routine X-ray diffraction techniques

2014 ◽  
Vol 2 (10) ◽  
pp. 3536 ◽  
Author(s):  
Aurélien Viterisi ◽  
Núria F. Montcada ◽  
Challuri Vijay Kumar ◽  
Francesc Gispert-Guirado ◽  
Eddy Martin ◽  
...  
Keyword(s):  
Solar Cell ◽  
Small Molecule ◽  
Molecular Packing ◽  
X Ray Diffraction ◽  
Solution Processed ◽  
X Ray ◽  
Unambiguous Determination

Anomalous small angle scattering

1981 ◽  
Vol 14 (3) ◽  
pp. 433-462 ◽  
Author(s):  
H. B. Stuhrmann
Keyword(s):  
Specific Binding ◽  
X Ray Diffraction ◽  
X Ray ◽  
Macromolecular Assemblies ◽  
Heavy Atoms ◽  
Partial Structures ◽  
Isomorphous Replacement ◽  
Angle Scattering ◽  
Structure Research

Isomorphous replacement methods have been revolutionary in macromolecular structure research. This has been most clearly demonstrated in protein crystallography. Specific binding of heavy atoms to protein molecules in the crystalline state provides the necessary reference for the phase determination of each Bragg reflexion and opens the way to the direct structure determination to atomic resolution from X-ray diffraction.Are isomorphous replacement methods applicable to the investigation of non-crystalline structures as well? And if so, would there be any reasonable advantage?An answer has been given by neutron scattering. Macromolecular assemblies of nucleic acids, proteins and lipids are most easily studied in H2O /D2O mixtures, as the scattering density of the solvent can be adjusted to any of the chemically different partial structures (Stuhrmann, 1974).

Structure of laserolide and isolaserolide: Revision of constitution and determination of relative and absolute configuration

1985 ◽  
Vol 50 (8) ◽  
pp. 1878-1887 ◽  
Author(s):  
Miroslav Holub ◽  
Miloš Buděšínský ◽  
Zdenka Smítalová ◽  
David Šaman ◽  
Urszula Rychłewska
Keyword(s):  
Diffraction Analysis ◽  
Absolute Configuration ◽  
Cd Spectroscopy ◽  
X Ray Diffraction ◽  
Physical Methods ◽  
X Ray

The position of the ester groups in sesquiterpenic lactones laserolide (I) and isolaserolide (II) has been revised and its relative and absolute configuration determined by chemical and physical methods (NMR and CD spectroscopy). The structure I was confirmed by X-ray diffraction analysis. Laserolide (I) is the first germacranolide found in the Umbelliferae family, isolaserolide (II) is the first representative of new stereostructural group of elemanolides - 5βH,6αH,7αH,10αCH3-elema-1,3-dien-6,12-olides.

Determination of the absolute configuration of 1,1′-binaphthyl and its derivatives by x-ray diffraction

1968 ◽  
Vol 9 (1) ◽  
pp. 97-102 ◽  
Author(s):  
Hiroshi Akimoto ◽  
Takayuki Shioiri ◽  
Yoichi Iitaka ◽  
Shun-ichi Yamada
Keyword(s):  
Absolute Configuration ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Absolute

Glycosylcarborane derivatives and the determination of the absolute configuration of a diastereomeric triol from x-ray diffraction

1990 ◽  
Vol 55 (3) ◽  
pp. 838-843 ◽  
Author(s):  
Julie L. Maurer ◽  
Fabienne Berchier ◽  
Anthony J. Serino ◽  
Carolyn B. Knobler ◽  
M. Frederick Hawthorne
Keyword(s):  
Absolute Configuration ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Absolute

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

Sesquiterpenic lactones of the Inula caspica BLUME species

1990 ◽  
Vol 55 (6) ◽  
pp. 1568-1579 ◽  
Author(s):  
Sergazy M. Adekenov ◽  
Miloš Buděšínský ◽  
Metram A. Abdikalikov ◽  
Coblandy M. Turdybekov ◽  
David Šaman ◽  
...  
Keyword(s):  
Absolute Configuration ◽  
Cd Spectroscopy ◽  
X Ray Diffraction ◽  
Relative Configuration ◽  
X Ray

From Inula caspica BLUME (Compositae) were isolated 3β-hydroxy-2α-senecioyloxyisoalantolactone (I), whose structure was confirmed by X-ray diffraction and completed by determination of its absolute configuration, and britannin (II) whose relative configuration was determined by X-ray diffraction and absolute configuration by CD spectroscopy.

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