Pigments of Fungi. LVI. Dermocanarin 7, a New Naphthalene - Dihydroanthracenone - Oxanthrone Trimer from an Australian Dermocybe Toadstool

1999 ◽  
Vol 52 (9) ◽  
pp. 875 ◽  
Author(s):  
Malcolm S. Buchanan ◽  
Melvyn Gill ◽  
Jin Yu ◽  
Somphone Phonh-Axa
Keyword(s):  
Spectroscopic Data ◽  
Macrocyclic Lactone ◽  
Unique Combination ◽  
Indigenous Australian ◽  
The Absolute ◽  
Absolute Stereochemistry

Dermocanarin 7 (3), a unique combination of a macrocyclic lactone of the dermocanarin class with an oxanthrone, is isolated from an indigenous Australian toadstool belonging to the genus Dermocybe. The structure of dermocanarin 7 (3) is determined mainly from spectroscopic data, while the absolute stereochemistry at the three chiral centres and at the chiral axis follows from the c.d. spectrum of (3) and the results of NOESY and other n.m.r. experiments.

Studies of Australian Ascidians. VI. Virenamides D and E, Linear Peptides from the Colonial Didemnid Ascidian Diplosoma virens

1997 ◽  
Vol 50 (4) ◽  
pp. 337 ◽  
Author(s):  
Yunjiang Feng ◽  
Bruce F. Bowden
Keyword(s):  
Great Barrier Reef ◽  
Spectroscopic Data ◽  
Two Dimensional ◽  
Barrier Reef ◽  
Minor Constituents ◽  
One Dimensional ◽  
The Absolute ◽  
Absolute Stereochemistry

Two new linear cytotoxic tripeptides, virenamides D and E, have been isolated as minor constituents of extracts of the didemnid ascidianDiplosoma virens collected on the Great Barrier Reef, Australia. Their structures were deduced from one-dimensional and two-dimensional n.m.r. spectroscopic data, and the absolute stereochemistry of virenamide E is proven by synthesis from virenamide A.

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.

Determination of the Absolute Stereochemistry of Cyclosmenospongine

2003 ◽  
Vol 66 (9) ◽  
pp. 1263-1265 ◽  
Author(s):  
Natalia K. Utkina ◽  
Vladimir A. Denisenko ◽  
Olga V. Scholokova ◽  
Aleksandra E. Makarchenko
Keyword(s):  
The Absolute ◽  
Absolute Stereochemistry

Stereoselective deprotonation of tropinone and reactions of tropinone lithium enolate

1992 ◽  
Vol 70 (10) ◽  
pp. 2618-2626 ◽  
Author(s):  
Marek Majewski ◽  
Guo-Zhu Zheng
Keyword(s):  
Acetic Acid ◽  
Ring Opening ◽  
Aldol Reaction ◽  
Ethyl Chloroformate ◽  
Lithium Diisopropylamide ◽  
Silver Acetate ◽  
Lithium Amides ◽  
Lithium Enolate ◽  
The Absolute ◽  
Absolute Stereochemistry

Tropinone (6) was deprotonated with lithium diisopropylamide and with chiral lithium amides (18–24) and the resulting enolates (two enantiomers) were treated with electrophiles. The aldol reaction with benzaldehyde and deuteration were both diastereoselective. The former yielded only one isomer (exo, anti) of the aldol 8a; the latter proceeded from the exo face. This selectivity permitted us to probe the deprotonation of tropinone with lithium amides; it was concluded that the reaction involves predominantly the exo axial protons. The reaction of tropinone enolate with ethyl chloroformate led, via a ring opening, to the cycloheptenone derivative 9. The reaction with methyl cyanoformate yielded, in the presence of silver acetate and acetic acid, the β-ketoester 8b; however, in the absence of these additives, and especially when 12-crown-4 was added to the enolate, a ring opening leading to the pyrrolidine derivative 10 occurred instead. Deprotonation of tropinone with chiral lithium amides proceeded with modest enantioselectivity. A synthesis of non-racemic anhydroecgonine via this strategy allowed establishing the absolute stereochemistry of deprotonation.

First synthesis and determination of the absolute stereochemistry of iso-cladospolide-B and cladospolides-B and C

2006 ◽  
Vol 47 (37) ◽  
pp. 6537-6540 ◽  
Author(s):  
G.V.M. Sharma ◽  
K. Laxmi Reddy ◽  
J. Janardhan Reddy
Keyword(s):  
The Absolute ◽  
Absolute Stereochemistry

The absolute stereochemistry of the ester functions of fumonisin B1

1999 ◽  
Vol 40 (24) ◽  
pp. 4515-4518 ◽  
Author(s):  
Oliver E. Edward ◽  
Barbara A. Blackwell ◽  
Alex B. Driega ◽  
Corrine Bensimon ◽  
John W. ApSimon
Keyword(s):  
Fumonisin B1 ◽  
The Absolute ◽  
Absolute Stereochemistry

scholarly journals New Chromones from a Marine-Derived Fungus, Arthrinium sp., and Their Biological Activity

Molecules ◽  
2018 ◽  
Vol 23 (8) ◽  
pp. 1982 ◽  
Author(s):  
Jie Bao ◽  
Fei He ◽  
Jin-Hai Yu ◽  
Huijuan Zhai ◽  
Zhi-Qiang Cheng ◽  
...  
Keyword(s):  
Biological Activity ◽  
Deep Sea ◽  
Spectroscopic Data ◽  
Radical Scavenging ◽  
Antioxidant Property ◽  
Electronic Circular Dichroism ◽  
Chromone Derivatives ◽  
Ic50 Values ◽  
Ester Method ◽  
The Absolute

Five new chromone derivatives, arthones A–E (1–5), together with eight known biogenetically related cometabolites (6–13), were isolated from a deep-sea-derived fungus Arthrinium sp. UJNMF0008. Their structures were assigned by detailed analyses of spectroscopic data, while the absolute configurations of 1 and 5 were established by electronic circular dichroism (ECD) calculations and that of 2 was determined by modified Mosher ester method. Compounds 3 and 8 exhibited potent antioxidant property with DPPH and ABTS radical scavenging activities, with IC50 values ranging from 16.9 to 18.7 μM. Meanwhile, no compounds indicated obvious bioactivity in our antimicrobial and anti-inflammatory assays at 50.0 μM.

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).

scholarly journals Photometric Study of two Southern Algol Type Binaries

1989 ◽  
Vol 107 ◽  
pp. 376-376
Author(s):  
K. D. Abhyankar ◽  
M. L. Vyas
Keyword(s):  
Spectroscopic Data ◽  
Main Sequence ◽  
Light Curves ◽  
The Other ◽  
Main Sequence Star ◽  
Photometric Study ◽  
The Absolute ◽  
Better Than ◽  
Absolute Dimensions

Complete UBV light-curves of RR-Lep and RX-Hya have been obtained during 1983-87 seasons. Preliminary elements were computed using modified Wellmann’s method. With these parameters as inputs Wilson-Devinney program was executed for Blue and Yellow passbands simultaneously in detached and semi-detached modes for both the systems. The semidetached mode fitted better than the other solution for both the systems. For RR-Lep, the absolute dimensions were computed by assuming the primary to be a slightly evolved main sequence star. For RX-Hya, the absolute dimensions were computed using Struve’s spectroscopic data. The following table gives all the elements for both the systems. The secondaries of both the systems are overluminous for their masses suggesting that they have lost considerable mass.

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