Studies of Australian soft corals. XXII. The structures of two novel sesquiterpenes and a nor sesquiterpene from Lemnalia africana, confirmed by a single-crystal X-ray study

1980 ◽  
Vol 33 (12) ◽  
pp. 2737 ◽  
Author(s):  
BF Bowden ◽  
JC Coll ◽  
SJ Mitchell ◽  
BW Skelton ◽  
AH White
Keyword(s):  
Single Crystal ◽  
Soft Corals ◽  
X Ray ◽  
The Absolute ◽  
Absolute Stereochemistry

The isolation of two new sesquiterpenes (3) and (8) and a novel nor sesquiterpene (16) from Lemnalia africana is reported. In each case, the absolute stereochemistry was deduced chemically and spectroscopically, and confirmed by a single-crystal X-ray study on a suitable derivative (7).

Confirmation of the Absolute Stereochemistry of Hispidol-B [(3S,23R,24S)-Tirucall-7-ene-3,23,24,25-tetrol]

1988 ◽  
Vol 41 (11) ◽  
pp. 1777 ◽  
Author(s):  
P Bhandari ◽  
N Chaichit ◽  
AI Gray ◽  
BW Skelton ◽  
PG Waterman ◽  
...  
Keyword(s):  
Single Crystal ◽  
Diffraction Study ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Absolute ◽  
Absolute Stereochemistry

The stereochemistry of hispidol-B has been confirmed as (3S,23R,24S)- tirucall-7-ene-3,23,24,25-tetrol by means of a single-crystal X-ray diffraction study.

Revised Absolute Configurations of Latifolic Acid and the Pyrrolizidine Alkaloid Latifoline

1988 ◽  
Vol 41 (11) ◽  
pp. 1781 ◽  
Author(s):  
JN Roitman ◽  
RY Wong
Keyword(s):  
Carboxylic Acid ◽  
Single Crystal ◽  
Pyrrolizidine Alkaloid ◽  
Crystallographic Analysis ◽  
Side Chain ◽  
X Ray ◽  
The Absolute ◽  
Absolute Stereochemistry

The absolute stereochemistry of (+)- latifolk acid has been determined by single-crystal X-ray crystallographic analysis to be (2S,3R,4R)-3- hydroxy-2,4-dimethyl-5-oxotetrahydrofuran-3-carboxylic acid. The configuration of the three chiral centres is opposite to that presently recorded in the literature. Accordingly, the configuration of the pyrrolizidine alkaloid, latifoline, which includes a latifolic acid side chain, must be revised.

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.

Studies of Australian soft corals. XXXII. The structure determination of degraded xenicin-type diterpenes from several Efflatounaria species

1983 ◽  
Vol 36 (11) ◽  
pp. 2279 ◽  
Author(s):  
BF Bowden ◽  
JC Coll ◽  
VA Patrick ◽  
DM Tapiolas
Keyword(s):  
Single Crystal ◽  
Chemical Transformation ◽  
Structure Determination ◽  
High Field ◽  
Soft Corals ◽  
X Ray ◽  
The Third

Three new diterpenes have been isolated from soft corals of the genus Efflatounaria (Coelenterata, Octocorallia, Alcyonacea, Xeniidae). The structure of the first compound (4) was elucidated on the basis of high-field 1H n.m.r. spectroscopy while that of the second metabolite (5) was determined by single-crystal X-ray analysis. The third diterpene (6) was structurally related to (5), and its structure was confirmed by chemical transformation. All three diterpenes can be derived from xenicin-type precursors, by cleavage and recyclization.

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.

Studies of Australian soft corals. IX. A novel nor-diterpene from the soft coral Sinularia leptoclados

1978 ◽  
Vol 31 (9) ◽  
pp. 2049 ◽  
Author(s):  
BF Bowden ◽  
JC Coll ◽  
SJ Mitchell ◽  
J Mulder ◽  
GJ Stokie
Keyword(s):  
Single Crystal ◽  
Spectroscopic Data ◽  
Soft Coral ◽  
Parent Compound ◽  
Soft Corals ◽  
X Ray

The structure of a novel nor-cembranoid diterpene of formula C19H24O6 (1) is reported. The compound was extracted from the soft coral Sinularia leptoclados, and spectroscopic data were collected on the parent compound (1) and a series of derivatives. It was not possible to assign an unambiguous structure on purely spectroscopic grounds, and so single-crystal X-ray analysis was used to prove the structure (1): (4R*,8S*,11R*,13S*,14R*)-14-hydroxy-4-isopropenyl-11-methyl-6,9-dioxo-8,11-epoxycyclotetradec-1-ene-1,13-carbolactone.

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.

The Constituents of Marine Sponges. VII. The Absolute Stereochemistry of Aplyroseol-1.

1997 ◽  
Vol 50 (4) ◽  
pp. 391 ◽  
Author(s):  
Trevor W. Hambley ◽  
Walter C. Taylor ◽  
Stephen Toth
Keyword(s):  
Crystal Structure ◽  
Marine Sponges ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
The Absolute ◽  
Absolute Stereochemistry

The absolute stereochemistry of aplyroseol-1 (1), a diterpenoid isolated from Aplysillarosea Barrois, has been established as (5S; 7R; 8S; 9R; 10S; 13R; 14R; 15R) by determining the crystal structure of the p-bromobenzoyl derivative (3) by X-ray diffraction methods. The structure was refined to a residual of 0·032 for 1451 independent observed reflections. The crystals are monoclinic, space group P 21, a 6·668(8), b 20·04(1), c 10·974(3) Å, β 98·04(7)°.

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