The structure and partial synthesis of imbricatine, a benzyltetrahydroisoquinoline alkaloid from the starfish Dermasterias imbricata

1991 ◽  
Vol 69 (1) ◽  
pp. 20-27 ◽  
Author(s):  
David L. Burgoyne ◽  
Shichang Miao ◽  
Charles Pathirana ◽  
Raymond J. Andersen ◽  
William A. Ayer ◽  
...  
Keyword(s):  
Key Words ◽  
Absolute Configuration ◽  
Spectroscopic Analysis ◽  
Chemical Degradation ◽  
Model Compounds ◽  
Partial Synthesis ◽  
The Absolute

The structure of imbricatine (1), a cytotoxic metabolite of the starfish Dermasterias imbricata, has been determined by spectroscopic analysis and chemical degradation. Synthesis of model compounds 7 and 18 provided evidence for the absolute configuration and constitution of the benzyltetrahydroisoquinoline substructure of imbricatine. Key words: imbricatine, asteroid, alkaloid.

scholarly journals Massiliamide, a cyclic tetrapeptide with potent tyrosinase inhibitory properties from the Gram-negative bacterium Massilia albidiflava DSM 17472T

2020 ◽  
Author(s):  
Andri Frediansyah ◽  
Jan Straetener ◽  
Heike Brötz-Oesterhelt ◽  
Harald Gross
Keyword(s):  
Absolute Configuration ◽  
Inhibitory Activity ◽  
Liquid Culture ◽  
Spectroscopic Analysis ◽  
2D Nmr ◽  
Negative Bacterium ◽  
Gram Negative ◽  
The Absolute ◽  
Potent Inhibitory Activity ◽  
Cyclic Tetrapeptide

AbstractA cyclic tetrapeptide, designated massiliamide, was isolated from the liquid culture of the Gram-negative bacterium Massilia albidiflava DSM 17472T. The structure was elucidated through extensive spectroscopic analysis, including HR-MS and 1D and 2D NMR experiments. The absolute configuration was determined using the Marfey´s method. Massiliamide showed potent inhibitory activity towards tyrosinase with an IC50 value of 1.15 µM and no cytotoxicity.

scholarly journals A New Bisabolene from Stevia tomentosa

2011 ◽  
Vol 6 (9) ◽  
pp. 1934578X1100600
Author(s):  
Alejandro Valdez-Calderón ◽  
J. Martín Torres-Valencia ◽  
J. Jesús Manríquez-Torres ◽  
René Velázquez-Jiménez ◽  
Mario A. Gómez-Hurtado ◽  
...  
Keyword(s):  
Absolute Configuration ◽  
Coupling Constants ◽  
Spectral Studies ◽  
Dihedral Angles ◽  
Model Compounds ◽  
H Nmr ◽  
Aerial Parts ◽  
The Absolute

The new sesquiterpene (1 R,2 R,3 R,6 R,7 S)-1-acetoxy-2,3-dmydroxy-2,3-dihydrobisabolene (3) together with ten known terpenes and three known flavonoids were isolated from the aerial parts and from the roots of Stevia tomentosa. The structure of 3 follows from spectral studies, the relative chirality at C-3 follows from 1H NMR coupling constants comparison with the corresponding calculated values obtained by applying a generalized Karplus-type relationship to the dihedral angles of model compounds, and the absolute configuration is assumed in analogy to known (2 R,3 R,6 R,7 S)-2,3-epoxy-2,3-dihydrobisabolen-1-one (2).

scholarly journals Chaetolactone, A Skeletally New Cyclopentenone from Chaetomium sp. C521

2018 ◽  
Vol 13 (7) ◽  
pp. 1934578X1801300 ◽  
Author(s):  
Wen-Bo Han ◽  
He Li ◽  
Hui-Yi Zhou ◽  
Jia Meng ◽  
Jin-Ming Gao ◽  
...  
Keyword(s):  
Botrytis Cinerea ◽  
Absolute Configuration ◽  
Magnaporthe Oryzae ◽  
Spectroscopic Analysis ◽  
Alternaria Solani ◽  
Carbon Skeleton ◽  
The Absolute

Chaetolactone, a new polyketide with an unprecedented carbon skeleton, was constructed by Chaetomium sp. C521. Its structure was characterized by a combination of detailed spectroscopic analysis and ECD method, which facilitated the establishment of the absolute configuration for chaetolactone. The new compound was tested for anti-phytopathogenic activity against Botrytis cinerea, Alternaria solani, Gibberella saubinettii, and Magnaporthe oryzae, but exhibited negligible inhibition at a concentration of 20 μM.

Determination of the absolute configuration of secondary alcohols by modified Horeau's method using HPLC

1989 ◽  
Vol 54 (1) ◽  
pp. 151-159 ◽  
Author(s):  
Aleš Svatoš ◽  
Irena Valterová ◽  
Anna Fábryová ◽  
Jan Vrkoč
Keyword(s):  
Absolute Configuration ◽  
Secondary Alcohols ◽  
Model Compounds ◽  
Defense Substance ◽  
Determination Of Absolute Configuration ◽  
The Absolute

A method for determination of absolute configuration of secondary alcohols, based on a modified Horeau's method, has been developed. The ratio of (1R,2'S)- and (1R,2'R)-N-[1-(1-naphthyl)-ethyl]-2-phenylbutanamides (V and VI, respectively) was determined by HPLC on a straight phase. The method was tested on a series of steroid and terpene model compounds and was used in the determination of absolute configuration of 15-ripperten-3α-ol (XV), the defense substance of Nasutitermes nigriceps termites. The sensibility of the determination is 100 nmol of the alcohol.

scholarly journals Use of Circular Dichroism to Determine the Absolute Configuration of a Pimarane Diterpenoid from the Southern African Sclerocroton integerrimus (Euphorbiaceae)

2014 ◽  
Vol 9 (8) ◽  
pp. 1934578X1400900 ◽  
Author(s):  
Vuyelwa J. Tembu ◽  
Moses K. Langat ◽  
Neil R. Crouch ◽  
Dulcie A. Mulholland
Keyword(s):  
Circular Dichroism ◽  
Absolute Configuration ◽  
Spectroscopic Analysis ◽  
Stem Bark ◽  
Electronic Circular Dichroism ◽  
The Absolute ◽  
Circular Dichroïsm

From the stem bark and leaves of Sclerocroton integerrimus, eight compounds, including 17-hydroxy- ent-pimara-8(14),15-dien-3-one (1), were isolated. The structures of the compounds were determined on the basis of spectroscopic analysis. The absolute configuration of 17-hydroxy- ent-pimara-8(14),15-dien-3-one was confirmed from electronic circular dichroism studies.

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.

The CFTA Method: A Reliable Procedure for the Determination of the Absolute Configuration of Chiral Primary Amines by1H NMR Spectroscopic Analysis

2006 ◽  
Vol 45 (28) ◽  
pp. 4617-4619 ◽  
Author(s):  
Yoshio Takeuchi ◽  
Masaru Segawa ◽  
Hidehito Fujisawa ◽  
Kenji Omata ◽  
Siegfried N. Lodwig ◽  
...  
Keyword(s):  
Absolute Configuration ◽  
Spectroscopic Analysis ◽  
Primary Amines ◽  
Reliable Procedure ◽  
The Absolute

Controlled diastereoselection in 2-lithio-1,3-dithiane additions onto α-substituted γ-lactols. Model studies toward bryostatins from (R)-pantolactone

1991 ◽  
Vol 69 (1) ◽  
pp. 62-69 ◽  
Author(s):  
René Roy ◽  
Allan W. Rey
Keyword(s):  
Key Words ◽  
Absolute Configuration ◽  
Nucleophilic Addition ◽  
Major Product ◽  
Model Studies ◽  
Nuclear Overhauser Enhancement ◽  
The Absolute ◽  
Nuclear Overhauser ◽  
Very High

Homochiral α-substituted γ-lactols 3 and 4 derived from (R)-pantolactone 1 were used in 2-lithio-1,3-dithiane additions to afford very high controls in diastereoselectivities arising from 1,2-asymmetric inductions. Thus non-chelation controlled nucleophilic addition on 3 gave the anti diastereomer 5 as the major product (92% de), while the chelation controlled addition on 4 furnished the syn diastereomer 7 (96% de) as the almost exclusive product. The stereochemical outcomes of these reactions were proven unambiguously by locking the conformation of the syn- and anti-triol adducts 7 and 8 through their respective acetonides and by nuclear Overhauser enhancement measurements. The lack of 1,3-dioxolane formation in the case of the anti-triol 8 was taken as a further confirmation of the absolute configuration at the newly created stereocenter. Key words: byrostatin, pantolactone, α-hydroxylactol, dithiane.

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.

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