The chemical constituents of Australian Flindersia species. XIX. Triterpenoids from the leaves of F. bourjotiana F. Muell

1966 ◽  
Vol 19 (3) ◽  
pp. 455 ◽  
Author(s):  
GJW Breen ◽  
E Ritchie ◽  
WTL Sidwell ◽  
WC Taylor
Keyword(s):  
Chemical Constituents ◽  
Chemical Degradation ◽  
Spectroscopic Methods ◽  
The Absolute ◽  
Absolute Stereochemistry

From the leaves of Flindersia bourjotinna F. Muell. there were isolated sitosterol, triacontanol, lupeol, germanicol, germanicone, and four new triterpenoids, the bourjotinolones A, B, and C, and bourjotone. By chemical degradation and spectroscopic methods, the structures of these substances were shown to be 21,24-epoxy-23,25-dihydroxytirucall-7-en-3one, 23,24-dihydroxytirucalla-7,25-dien- 3-one, 25-chloro-23,24-dihydroxytirucall-7-en-3-one, and 25,26,27-trisnortirucall-7- ene-3,23-dione, respectively. Bourjotinolone C is almost certainly an artefact but bourjotinolone B and bourjotone are less likely to be. From biogenetic and N.M.R. spectral considerations, the absolute stereochemistry of the new triterpenes may be deduced.

New Chromenols From a Southern Australian Tunicate, Aplidium solidum

1996 ◽  
Vol 49 (11) ◽  
pp. 1217 ◽  
Author(s):  
SJ Rochfort ◽  
R Metzger ◽  
L Hobbs ◽  
RJ Capon
Keyword(s):  
Spectroscopic Analysis ◽  
Chemical Degradation ◽  
The Absolute ◽  
Absolute Stereochemistry

Two new chromenols, namely (R)-2-methyl-2-(4-methylpenta-1,3-dienyl)-2H-chromen-6-ol (7) and 1-[(R)-6-hydroxy-2-methyl-2H-chromen-2-yl]-4-methylpentan-2-one (8), have been isolated from a southern Australian tunicate, Aplidium solidum. The structures of (7) and (8) were assigned by spectroscopic analysis, and the absolute stereochemistry of (7) by chemical degradation.

Pigments of Fungi. LII Anisochiral Flavomannin 6,6′,8-Tri-O-methyl Ether from an Australian Dermocybe Toadstool

1999 ◽  
Vol 52 (8) ◽  
pp. 749 ◽  
Author(s):  
Malcolm S. Buchanan ◽  
Melvyn Gill ◽  
Alberto Gimenez ◽  
Somphone Phonh-Axa ◽  
Evelin Raudies ◽  
...  
Keyword(s):  
Natural Product ◽  
Methyl Ether ◽  
Absolute Configuration ◽  
Enantiomeric Purity ◽  
Chemical Degradation ◽  
Spectroscopic Methods ◽  
Fruiting Bodies ◽  
The Absolute

Flavomannin 6,6′,8-tri-O-methyl ether occurs in the fruiting bodies of the Australian toadstool Dermocybe sp. WAT 24274 as an anisochiral mixture of the (3S,3′S,P)- and (3R,3′R,M)-enantiomers (5) and (7), respectively, in which the former predominates to the extent of 50% e.e. The structure of the natural product is determined by spectroscopic methods and the absolute configuration and enantiomeric purity are deduced from the c.d. spectrum and by chemical degradation of the natural product to a mixture of stereoisomeric dihydroanthracenones that has been analysed by chiral h.p.l.c.

scholarly journals Novel Resorcinol Derivatives from Lasiodiplodia theobromae

2000 ◽  
Vol 55 (7-8) ◽  
pp. 546-551 ◽  
Author(s):  
Qing Yang ◽  
Maki Asai ◽  
Teruhiko Yoshihara
Keyword(s):  
Asymmetric Center ◽  
Spectroscopic Methods ◽  
Lasiodiplodia Theobromae ◽  
The Absolute ◽  
Absolute Stereochemistry

Abstract Two novel resorcinol derivatives were isolated from the mycelium of Lasiodiplodia theobromae IFO 31059 as potato micro-tuber inducing compounds. Their structures were established by spectroscopic methods as ethyl (6′R)-2,4-dihydroxy-6-(6′-hydroxyheptyl)benzoate (8) and isobutyl (6′R)-2.4-dihydroxy-6-(6′-hydroxyheptyl)benzoate (9). The absolute stereochemistry of the asymmetric center of (8) was determined by an advanced Mosher method.

Metabolites of the fungus Arthropsistruncata

1992 ◽  
Vol 70 (5) ◽  
pp. 1338-1347 ◽  
Author(s):  
William A. Ayer ◽  
Peter A. Craw ◽  
John Neary
Keyword(s):  
Spectroscopic Methods ◽  
Liquid Cultures ◽  
X Ray ◽  
Crystallographic Study ◽  
The Absolute ◽  
Absolute Stereochemistry

The structures of 12 new polyketide metabolites produced in liquid cultures of the fungus Arthropsistruncata have been determined by a combination of chemical and spectroscopic methods. Four of these metabolites possess an unusual 2-oxaspiro[4.5]decane skeleton, and the structure assigned to one of these metabolites 20 has been confirmed by an X-ray crystallographic study of the dibenzoyl derivative 21. The absolute stereochemistry of these compounds has been predicted by application of the Harada–Nakanishi dibenzoate rule to arthropsolide D tribenzoate (32).

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.

The Siderophores of Pseudomonas fluorescens 18.1 and the Importance of Cyclopeptidic Substructures for the Recognition at the Cell Surface

2000 ◽  
Vol 55 (9-10) ◽  
pp. 671-680 ◽  
Author(s):  
Cordula Amann ◽  
Kambiz Taraz ◽  
Herbert Budzikiewicz ◽  
Jean-Marie Meyer
Keyword(s):  
Cell Surface ◽  
Pseudomonas Fluorescens ◽  
Mutual Recognition ◽  
Chemical Degradation ◽  
Spectroscopic Methods

Abstract The structure of the pyoverdin siderophore of Pseudomonas fluorescens 18.1 was elucidated by spectroscopic methods and chemical degradation. By cross feeding studies structurally closely related pyoverdins containing a C-terminal cyclopeptidic substructure were tested regarding the mutual recognition by the producing strains. Partial recognition of foreign pyoverdins was observed.

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
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