Absolute Stereochemistry of (-)-Wieland-Miescher Ketone as Established by the X-ray Crystallographic and CD Exciton Chirality Methods

1992 ◽  
Vol 57 (7) ◽  
pp. 1459-1465 ◽  
Author(s):  
Nobuyuki Harada ◽  
Tatsuo Sugioka ◽  
Hisashi Uda ◽  
Takeo Kuriki
Keyword(s):  
Structure Analysis ◽  
Absolute Configuration ◽  
X Ray ◽  
The Absolute ◽  
Absolute Stereochemistry

The 8aR absolute stereochemistry of Wieland-Miescher ketone (-)-I was established by the X-ray structure analysis of its bis(4-bromobenzoate) derivatives (1R,6R,8aR)-(+)-IV and (1R,6S,8aR)-(-)-V. The absolute configuration of (-)-I was corroborated further by the application of the CD exciton chirality method to bis(4-bromobenzoates) (+)-IV and (-)-V.

scholarly journals Preparative-scale HPLC Resolution of Metallacyclic η3-Allyltricarbonyliron Complexes and Determination of the Absolute Configuration by X-Ray Crystal Structure Analysis

1999 ◽  
Vol 23 (9) ◽  
pp. 578-579
Author(s):  
Rainer Schobert ◽  
Hermann Pfab ◽  
Jutta Böhmer ◽  
Frank Hampel ◽  
Andreas Werner
Keyword(s):  
Crystal Structure ◽  
Silica Gel ◽  
Structure Analysis ◽  
Absolute Configuration ◽  
Crystal Structure Analysis ◽  
Preparative Scale ◽  
X Ray ◽  
The Absolute

Racemates of (η3-allyl)tricarbonyliron lactone complex Fe(CO)3{η1:η3-C(O)XCH2CHCMeCH2} 1a (X = O) and (η3-allyl)tricarbonyliron lactam complex 2a (X = NMe) are resolved on a preparative scale by HPLC on cellulose tris(3,5-dimethylphenyl)carbamate/silica gel RP-8 and the absolute configuration of (-)-2a is determined by X-ray crystal structure analysis.

THE REACTION OF UNSATURATED CARBOHYDRATES WITH CARBON MONOXIDE AND HYDROGEN: V. ABSOLUTE STEREOCHEMISTRY OF ANHYDRODEOXYHEPTITOLS FROM 3,4,6-TRI-O-ACETYL-D-GLUCAL. STEREOCHEMISTRY OF HYDROFORMYLATION. CONFORMATIONAL ANALYSIS

1965 ◽  
Vol 43 (5) ◽  
pp. 1375-1381 ◽  
Author(s):  
Alex Rosenthal ◽  
Hans J. Koch
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Carbon Monoxide ◽  
Absolute Configuration ◽  
Sodium Iodide ◽  
Crystallographic Analysis ◽  
X Ray ◽  
Dicobalt Octacarbonyl ◽  
The Absolute ◽  
Compound Ii ◽  
Absolute Stereochemistry

3,4,6-Tri-O-acetyl-D-glucal reacted with carbon monoxide and hydrogen in the presence of dicobalt octacarbonyl to yield a mixture of two epimeric anhydrodeoxyheptitols, namely, 4,5,7-tri-O-acetyl-2,6-anhydro-3-deoxy-D-manno-heptitol (I) and 4,5,7-tri-O-acetyl-2,6-anhydro-3-deoxy-D-gluco-heptitol (II). De-O-acetylation of the mixture, followed by chromatographic separation, yielded crystalline 2,6-anhydro-3-deoxy-D-manno-heptitol (III) and 2,6-anhydro-3-deoxy-D-gluco-heptitol (IV). Reaction of the mixture of heptitols (I) and (II) with p-bromobenzenesulfonyl chloride, followed by fractional crystallization of the brosylates, gave pure 4,5,7-tri-O-acetyl-2,6-anhydro-1-O-(p-bromophenylsulfonyl)-3-deoxy-D-gluco-heptitol (VII). The absolute configuration of (VII) has been previously established by X-ray crystallographic analysis. The absolute configuration of (III) was established by correlation with that of (VII). The conversion of compound (II) into various derivatives is described.Reaction of 3,4,6-tri-O-acetyl-D-glucal with carbon monoxide and deuterium afforded 2,6-anhydro-3-deoxy-D-manno-heptitol-1,1,3-2H3 (XIII) and 2,6-anhydro-3-deoxy-D-gluco-heptitol-1,1,3-2H3 (XIV). Examination of the nuclear magnetic resonance (n.m.r.) spectra of the normal and deuterated anhydrodeoxyheptitols confirmed the structural assignments and showed that cis addition to the double bond took place to give (XIV).Comparison of the exchange reaction of sodium iodide with 4,5,7-tri-O-acetyl-2,6-anhydro-3-deoxy-1-O-tosyl-D-gluco-heptitol (VIII) and with 4,5,7-tri-O-acetyl-2,6-anhydro-3-deoxy-1-O-tosyl-D-manno-heptitol (XV) revealed that the equatorial primary tosyloxy group of (VIII) was exchanged by iodine twice as readily as the axial primary tosyloxy group of (XV).

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.

Sterically Crowded Heterocycles. XIII. An Insight Into the Absolute Stereochemistry of Atropisomeric (Z)-3-(Imidazo[1,2-a]pyridin-3-yl)prop-2-en-1-ones

2000 ◽  
Vol 65 (10) ◽  
pp. 1643-1652
Author(s):  
Radek Pohl ◽  
Jan Sýkora ◽  
Petr Maloň ◽  
Stanislav Böhm ◽  
Bohumil Kratochvíl ◽  
...  
Keyword(s):  
Absolute Configuration ◽  
Heats Of Formation ◽  
Cd Spectra ◽  
X Ray ◽  
Space Analysis ◽  
The Absolute ◽  
Absolute Stereochemistry ◽  
Insight Into

The absolute configuration of the atropisomeric (Z)-3-(5-methyl-2-phenylimidazo[1,2-a]pyridin-3-yl)-1,3-diphenylprop-2-en-1-one was evaluated to be R for the dextrorotatory and S for the laevorotatory enantiomers. The assignment is based on their two-step syntheses via atropodiastereoisomeric carbamates prepared from the corresponding atropodiastereoisomeric alcohols with (R)-(+)-α-phenylethyl isocyanate and by a complete X-ray space analysis of the quaternary triiodide obtained from the (R)-(+)-enantiomer. CD spectra and PM3 calculated heats of formation for selected compounds are discussed in relation to the found molecular configurations.

Metabolites produced by the scleroderris canker fungus, Gremmeniellaabietina. Part 2. The structure of scleroderolide

1987 ◽  
Vol 65 (4) ◽  
pp. 748-753 ◽  
Author(s):  
William A. Ayer ◽  
Yumiko Hoyano ◽  
M. Soledade Pedras ◽  
Jon Clardy ◽  
Edward Arnold
Keyword(s):  
Absolute Configuration ◽  
Temperature Dependent ◽  
X Ray ◽  
Triclinic System ◽  
R Factor ◽  
Racemic Form ◽  
Crystallographic Study ◽  
Acetyl Group ◽  
The Absolute ◽  
Absolute Stereochemistry

Scleroderolide, a yellow pigment produced by the Scleroderris canker fungus Gremmeniellaabietina (Lagerb.) Morelet, is shown to possess structure 1. The structure was determined by an X-ray crystallographic study of the racemic monoacetate 1a. The crystal of 1a belongs to the triclinic system space group, P1, the R-factor converged to 0.047 for the 1957 observed reflections. Scleroderolide occurs mainly as the levorotatory enantiomer (S configuration at C-2′) although on one occasion it was obtained in partially racemic form. The absolute stereochemistry of the levorotatory form was determined by transformation of (−)-sclerodione (5) of known absolute configuration into (−)-scleroderolide. The absolute configuration of (−)-sclerodione was established by correlation with (−)-sclerodin (3). The diacetyl derivative of scleroderolide (1b) shows interesting temperature dependent nuclear magnetic resonance spectral properties due to restricted rotation of the C-4 O-acetyl group. Oxidation of the red pigment sclerodione (5) with m-chloroperbenzoic acid provides both sclerodin (3) and scleroderolide (1). Scleroderolide (1) is the first natural product to be reported that contains a phenylglyoxylate lactone functionality.

The Absolute Stereochemistry of the Galbulimima Alkaloids

2006 ◽  
Vol 59 (9) ◽  
pp. 629 ◽  
Author(s):  
Anthony C. Willis ◽  
Patrick D. O'Connor ◽  
Walter C. Taylor ◽  
Lewis N. Mander
Keyword(s):  
Crystal Structures ◽  
Absolute Configuration ◽  
X Ray ◽  
The Absolute ◽  
Absolute Stereochemistry

The X-ray crystal structures have been determined for three alkaloids isolated from the bark of the rainforest tree Galbulimima belgraveana, namely himbosine, himandrine, and himgaline, thereby allowing the absolute configuration to be established for these three compounds and 15 further alkaloids from this source.

Röntgenstrukturanalyse von Mezerein aus Daphne mezereum L. / X-Ray Structure Analysis of Mezerein from Daphne mezereum L

1977 ◽  
Vol 32 (9-10) ◽  
pp. 678-682 ◽  
Author(s):  
H. Lotter ◽  
A. Jones ◽  
M. Sturm
Keyword(s):  
Structure Analysis ◽  
Absolute Configuration ◽  
Direct Methods ◽  
Antileukemic Activity ◽  
Methods Comparison ◽  
X Ray ◽  
The Absolute

Abstract Mezerein, Daphne mezereum, X-Ray Structure, Antileukemic Principle The X-ray structure of Mezerein from Daphne mezereum L. was determined by aid of direct methods. Comparison with Phorbol and Daphnetoxin led to the absolute configuration. A tentative mechanism for the antileukemic activity is proposed.

Novel Bromo Metabolites From a Dictyoceratid Sponge of the Cacospongia Genus

1989 ◽  
Vol 42 (5) ◽  
pp. 611 ◽  
Author(s):  
MJ Garson ◽  
DC Manker ◽  
KE Maxwell ◽  
BW Skelton ◽  
AH White
Keyword(s):  
Structure Analysis ◽  
Absolute Configuration ◽  
Marine Sponge ◽  
Carbon Skeleton ◽  
Crystallographic Structure ◽  
X Ray ◽  
The Absolute ◽  
New Compounds

Two novel brominated metabolites, tribromocacoxanthene (3) and tetrabromocacoxanthene (4),have been isolated from a marine sponge of the Cacospongia genus (family Thorectidae ) along with 12-epideoxoscalarin (2). The structures of compounds (3), systematic name (2S,4aS,9aS)-2,7-dibromo-4a-bromomethyl-1,1-dimethyl-2,3,4,4a,9,9a-hexahydro-1H-xanthene, and (4), systematic name (2S,4aS,9aS)-2,5,7-tribromo-4a-bromomethyl-l,1-dimethyl-2,3,4,4a,9,9a-hexahydro-1H-xanthene , were deduced from analysis of 1H and 13C n.m.r. data and that of (3) was confirmed by X-ray crystallographic structure analysis which provided the absolute configuration. The two new compounds are the first tricyclic examples of a carbon skeleton previously isolated only from algae. The chemotaxonomic implication of the isolation of these new compounds is discussed.

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