A novel lipid from the brown alga Notheia anomala

1980 ◽  
Vol 33 (4) ◽  
pp. 891 ◽  
Author(s):  
RG Warren ◽  
RJ Wells ◽  
JF Blount
Keyword(s):  
Single Crystal ◽  
Spectral Data ◽  
Absolute Configuration ◽  
Brown Alga ◽  
X Ray ◽  
Relative Stereochemistry ◽  
The Absolute

The brown alga Notheia anomala has yielded a C19 lipid diol, (6S,7S,9R,10R)-6,9-epoxynonadec-18-ene-7,10-diol, as the major component. The structure, assigned on the basis of spectral data, was confirmed by single-crystal X-ray analysis, which also established the relative stereochemistry. The absolute configuration was determined on the monoacetate by the Horeau method.

Die absolute Konfiguration der Juglomycine/The Absolute Configuration of the Juglomycins

1989 ◽  
Vol 44 (3) ◽  
pp. 345-352 ◽  
Author(s):  
Johann Krupa ◽  
Helmut Lackner ◽  
Peter G. Jones ◽  
Karen Schmidt-Bäse ◽  
George M. Sheldrick
Keyword(s):  
Single Crystal ◽  
Structure Analysis ◽  
Absolute Configuration ◽  
X Ray ◽  
The Absolute ◽  
Dibromo Derivative

The absolute configurations of the known juglomycins A (1) and B (2) have been elucidated by single crystal X-ray structure analysis of 1 and its 6,8-dibromo derivative (1b). The structure of 2 has been corrected; it differs from 1 in its configuration at C-4', and not at C-3' as previously assumed. Relationships with the closely related isochromanquinone antibiotics are discussed.

Structure of a New Dolastane Diterpene From Dictyota furcellata

1989 ◽  
Vol 42 (2) ◽  
pp. 315 ◽  
Author(s):  
RW Dunlop ◽  
EL Ghisalberti ◽  
PR Jefferies ◽  
BW Skelton ◽  
AH White
Keyword(s):  
Diffraction Study ◽  
Absolute Configuration ◽  
Brown Alga ◽  
X Ray Diffraction ◽  
X Ray ◽  
Spectral Evidence ◽  
Relative Stereochemistry

The structure and relative stereochemistry of a new dolastane diterpene isolated from the brown alga Dictyota furcellata has been determined from spectral evidence and an X-ray diffraction study. Crystals are monoclinic, P21, a 15.762(5), b 15 562(5), c 9.599(6) � , β 100.05(4)° Z 4; R was 0.065 for 3587 'observed' reflections. If the dolastane absolute configuration is assumed, the compound is shown to be (6S,7R,14S)-6,7-diacetoxydolasta-l(15),8-dien-14-ol (1).

Euryachins A and B, a new type of diterpenoids from Eurya chinensis with potent NO production inhibitory activity

RSC Advances ◽  
2016 ◽  
Vol 6 (89) ◽  
pp. 85958-85961 ◽  
Author(s):  
Jia-Ling Song ◽  
Yao Yuan ◽  
Hai-Bo Tan ◽  
Jie-Wei Wu ◽  
Ri-Ming Huang ◽  
...  
Keyword(s):  
Single Crystal ◽  
Absolute Configuration ◽  
Inhibitory Activity ◽  
No Production ◽  
X Ray Diffraction ◽  
X Ray ◽  
New Type ◽  
The Absolute

Euryachins A (1) and B (2), new typediterpenoid euryamanes, were isolated from the branches of Eurya chinensis. The absolute configuration of 1 was determined by single-crystal X-ray diffraction. Both 1 and 2 exhibited significant NO production inhibitory activity.

Oxetanes from Photocycloaddition of 2-Aminopropenenitriles to Methyl Phenylglyoxylate and Benzils

2006 ◽  
Vol 61 (3) ◽  
pp. 301-310 ◽  
Author(s):  
Christiane van Wolven ◽  
Dietrich Döpp ◽  
Gerald Henkel
Keyword(s):  
Single Crystal ◽  
Absolute Configuration ◽  
Structure Determination ◽  
Benzene Solution ◽  
X Ray ◽  
H Nmr ◽  
The Absolute ◽  
Layer Chromatography ◽  
Preparative Layer Chromatography

Abstract By irradiation of methyl phenylglyoxylate (1) in benzene solution in presence of equimolar amounts of 2-aminopropenenitriles H2C=C(NR2)CN (3a - e, NR2 = morpholino, 1-pyrrolidinyl, 1-piperidinyl, hexamethyleneimino, heptamethyleneimino) the corresponding 2R∗,3R∗ head-to-head oxetanes 4a - e were obtained in moderate yields (11 - 52%) along with 2 - 28% of rac-dimethyl 2,3- diphenyltartrate (2). In presence of (S)-2-(2-methoxymethylpiperidin-1-yl)propenenitrile ((+)-3g) 1 is transformed into 26% of 2 and 33% of a mixture of diastereomeric oxetanes 4g,4’g in a ratio of 1.4 : 1 which could be improved to 2.5 : 1 by preparative layer chromatography. The absolute configuration of the major diastereomer 4g was unambiguously confirmed by a single crystal X-ray structure determination to be 2R,3R,2’S. Analogous photoadditions to benzil (5a), 4,4’-bis-(trifluoromethyl)benzil (5b) and 4,4’-dichlorobenzil (5c) with (+)-3g and its lower homologue (S)-2-(2-methoxymethylpyrrolidin- 1-yl)propenenitrile ((-)-3f) gave oxetanes only in low yield as detected by 1H NMR. Byproducts arise from competitive symmetrical α-cleavage of 5.

scholarly journals Memorial Issue Dedicated to Dr. Howard D. Flack: The Man behind the Flack Parameter

Chemistry ◽  
2021 ◽  
Vol 3 (3) ◽  
pp. 818-820
Author(s):  
Catherine E. Housecroft ◽  
Katharina M. Fromm
Keyword(s):  
Single Crystal ◽  
Absolute Configuration ◽  
Molecular Species ◽  
Crystalline Material ◽  
Special Issue ◽  
X Ray Diffraction ◽  
X Ray ◽  
Memorial Issue ◽  
The Absolute ◽  
Absolute Structure

This Special Issue of Chemistry is dedicated to Dr. Howard D. Flack (1943–2017), a renowned crystallographer who transformed the way in which, by using single crystal X-ray diffraction, we are able to determine the absolute structure of a crystalline material, and thereby determine the absolute configuration of molecular species within the material [...]

Vibrational circular dichroism and single crystal X-Ray diffraction analyses of [Ir(bzq)2(phen)]+ (bzq = benzo[h]quinoline; phen = 1,10-phenanthroline): absolute configuration and role of CH–π interaction in molecular packing

2017 ◽  
Vol 46 (13) ◽  
pp. 4397-4402 ◽  
Author(s):  
Kazuyoshi Takimoto ◽  
Yutaka Watanabe ◽  
Shigeki Mori ◽  
Hisako Sato
Keyword(s):  
Circular Dichroism ◽  
Single Crystal ◽  
Absolute Configuration ◽  
Molecular Packing ◽  
Vibrational Circular Dichroism ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Absolute ◽  
Circular Dichroïsm

The absolute configuration of a cationic iridium(iii) complex was determined in solution and solid by vibrational circular dichroism and X-ray diffraction analyses.

Crystal structure of aristoserratine

1983 ◽  
Vol 36 (5) ◽  
pp. 1037 ◽  
Author(s):  
IRC Bick ◽  
MA Hai ◽  
VA Patrick ◽  
AH White
Keyword(s):  
Crystal Structure ◽  
Circular Dichroism ◽  
Single Crystal ◽  
Absolute Configuration ◽  
Circular Dichroism Spectrum ◽  
X Ray Diffraction ◽  
Relative Configuration ◽  
X Ray ◽  
The Absolute ◽  
Circular Dichroïsm

The crystal structure of the alkaloid aristoserratine,* C20H24N2O, has been determined by single-crystal X-ray diffraction methods at 295 K, the structure being refined to a residual of 0.034 for 1107 independent 'observed' reflections. Crystals are monoclinic, P21, a 14.836(5), b 8.568(3), c 6.633(3) �, β 98.05(3)�, Z 2. The relative configuration is established and, by inference, by comparison of the circular dichroism spectrum with that of aristoteline, the absolute configuration is assigned.

A New Series of Diterpenes from Australian Spongia Species

1979 ◽  
Vol 32 (4) ◽  
pp. 867 ◽  
Author(s):  
R Kazlauskas ◽  
PT Murphy ◽  
RJ Wells ◽  
K Noack ◽  
WE Oberhansli ◽  
...  
Keyword(s):  
Great Barrier Reef ◽  
Single Crystal ◽  
Absolute Configuration ◽  
Spectral Methods ◽  
Barrier Reef ◽  
X Ray ◽  
The Absolute ◽  
New Compounds ◽  
The Relationship ◽  
Circular Dichroïsm

Great Barrier Reef sponges of the genus Spongia have yielded eight closely related tetracyclic furanoditerpenes. The structures, assigned on the basis of spectral methods, have been confirmed by a single-crystal X-ray analysis of one of the metabolites and the relative stereochemical features have been defined. The absolute configuration of this metabolite was determined by circular dichroism, which allowed the relationship between the eight new compounds to be determined.

The Absolute Structure of Latifoline

1992 ◽  
Vol 45 (2) ◽  
pp. 451 ◽  
Author(s):  
CCJ Culvenor ◽  
MF Mackay
Keyword(s):  
Single Crystal ◽  
Absolute Configuration ◽  
Crystallographic Analysis ◽  
Salt Hydrate ◽  
Space Group ◽  
X Ray ◽  
Orthorhombic Crystals ◽  
The Absolute ◽  
Absolute Structure

The absolute structure of latifoline, a pyrrolizidine diester alkaloid of retronecine and latifolic and angelic acids, has been defined by single-crystal X-ray crystallographic analysis of the hydrobromide salt hydrate. Orthorhombic crystals of C20H27NO7.HBr.H2O belong to the space group P 2′2′2′ with a 7.279(1), b 17.898(3), c 17.922(2) � and V 2334-9(8) � 3 . The structure has been refined to an R index of 0.054 for 1725 observed terms. The absolute configuration has been assigned by comparison with that of retronecine and also determined independently by X-ray examination of selected Bijvoet pairs. Our results have shown that the absolute structure of latifolic acid is 13S,14R,19S (2R,3S,4S in latifolic acid numbering), and not the stereoisomer reported recently by Roitman and Wong.

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