698. Ipecacuanha alkaloids. Part VI. The absolute stereochemistry at position 1 of emetine by chemical correlation with the natural amino-acids

1960 ◽  
pp. 3474 ◽  
Author(s):  
A. R. Battersby ◽  
R. Binks ◽  
T. P. Edwards
Keyword(s):  
Amino Acids ◽  
Chemical Correlation ◽  
The Absolute ◽  
Natural Amino Acids ◽  
Absolute Stereochemistry

Beyond Polygodial: New Drimane Sesquiterpenes From a Southern Australian Marine Sponge, Dysidea sp.

1993 ◽  
Vol 46 (8) ◽  
pp. 1255 ◽  
Author(s):  
MS Butler ◽  
RJ Capon
Keyword(s):  
Marine Sponge ◽  
Structure Elucidation ◽  
Spectroscopic Analysis ◽  
Marine Metabolites ◽  
Ecological Relationship ◽  
Chemical Correlation ◽  
The Absolute ◽  
First Time ◽  
Absolute Stereochemistry

This report describes the isolation and structure elucidation of four new drimane sesquiterpenes (14)-(17) from a southern Australian marine sponge Dysidea sp. The structures for (14)-(17) were secured by detailed spectroscopic analysis, chemical interconversion and derivatization. Also reported are the known metabolites (+)- euryfuran (7), dihydropallescensin-2 (18), (-)- pallescensin-A (19) and (-)-7-deacetoxyolepupane (6). The rare co-occurrence of two antipodes, (7) and (19), in the same specimen highlights the dangers in assigning absolute stereochemistry based on 'unproven' biosynthetic relationships. The absolute stereochemistry for (6) has been unambiguously established for the first time by chemical interconversion to (7). Furthermore, the absolute stereochemistry of the new marine metabolites listed above, (14)-(17), were determined by chemical correlation to (6). A biosynthetic and ecological relationship is proposed between the metabolites from Dysidea sp. with the known marine and terrestrial antifeedant polygodial (8). Chemical investigations are reported that support this proposition.

Stereospecific synthesis of hexahydrobenzopyrroloisoquinoline and tetrahydrobenzisoquinoline derivatives

1984 ◽  
Vol 37 (4) ◽  
pp. 819 ◽  
Author(s):  
E Gellert ◽  
N Kumar
Keyword(s):  
Amino Acids ◽  
Metal Hydride ◽  
Optically Active ◽  
Stereospecific Synthesis ◽  
Hydride Reduction ◽  
The Absolute ◽  
Absolute Stereochemistry

New optically active hexahydrobenzopyrroloisoquinoline and tetrahydrobenzisoquinoline derivatives have been synthesized. Metal hydride reduction of the cyclic amino ketones, prepared by mild Friedel-Crafts type intramolecular acylation of N-naphthalenylmethyl amino acids, yielded pairs of diastereoisomeric alcohols. The absolute stereochemistry and some features of the n.m.r. spectra of hexahydrobenzopyrroloisoquinolines, tetrahydrobenzisoquinoline and those of their intermediates are discussed.

The Luffarins (A-Z), Novel Terpenes From an Australian Marine Sponge, Luffariella geometrica

1992 ◽  
Vol 45 (10) ◽  
pp. 1705 ◽  
Author(s):  
MS Butler ◽  
RJ Capon
Keyword(s):  
Natural Products ◽  
Marine Sponge ◽  
Coastal Waters ◽  
Marine Natural Products ◽  
Spectroscopic Analysis ◽  
Marine Metabolites ◽  
Chemical Correlation ◽  
The Absolute ◽  
Great Australian Bight ◽  
Absolute Stereochemistry

A marine sponge, Luffariella geometrica Kirkpatrick, collected from the southern Australian coastal waters of the Great Australian Bight, has been found to contain 14 new bicyclic sesterterpenes, luffarin-A (14), -B (15), -C (16), -D (17), -E (18), -F (19), -G (20), -H (21), -I (22), -J (23), -K (24), -L (25), -M (26) and -N (27), a new bicyclic bisnorsesterterpene, luffarin-O (30), a new monocyclic sesterterpene, luffarin-P (32), six new acyclic sesterterpenes, luffarin-Q (35), -R (36), -S (37), -T (38), -U (39) and -V (40), two new diterpenes, luffarin-W (41) and -X (44), and two new bisnorditerpenes luffarin-Y (45) and -Z (46). These novel marine metabolites have been assigned structures, including stereochemistry, on the basis of detailed spectroscopic analysis, chemical correlation, derivatization, and biosynthetic considerations. Studies directed at the absolute stereochemistry of the luffarins have also permitted assignment of absolute stereochemistry to the known marine natural products (E)-neomanoalide (3), (Z)-neomanoalide (4) and dehydroambliol-A (47).

Absolute configuration at C(20) of the derivatives of 21-nor-5α-cholane-20,24-diol

1980 ◽  
Vol 45 (9) ◽  
pp. 2443-2451
Author(s):  
Vladimír Pouzar ◽  
Miroslav Havel
Keyword(s):  
Absolute Configuration ◽  
Side Chain ◽  
Chemical Correlation ◽  
The Absolute ◽  
Derivatives Of

Derivatives of 21-nor-5α-cholane-20,24-diol XI and XIX were prepared by stepwise construction of the side-chain in the position 17β. Their absolute configuration at C(20) was determined on the basis of chemical correlation with the derivatives of 21-nor-5α-cholan-20-ol, XVI and XXIV. The absolute configuration of alcohols XVI and XXIV was determined from the ratio of the yields in which they are formed during the reduction of ketone X and using the benzoate rule. To compounds XI-XVIII the configuration 20R and to compounds XIX-XXVI the configuration 20S has been assigned.

Synthesis and characteristics of ethylenediamine-N,N'-di-S-α-isovalerate and isomers of its cobalt(III) complexes

1982 ◽  
Vol 47 (1) ◽  
pp. 210-216 ◽  
Author(s):  
Milan Strašák ◽  
František Bachratý ◽  
Jaroslav Majer
Keyword(s):  
Amino Acids ◽  
Absolute Configuration ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Chemical Parameters ◽  
Methyl Group ◽  
Nmr Data ◽  
Physico Chemical ◽  
Natural Amino Acids ◽  
C Nmr

The synthesis and physico-chemical parameters are described of a new complexone based on natural amino acids, viz. ethylenediamine-N,N'-di-S-α-isovalerate (SS-EDDIV). 1H- and 13C-NMR data revealed that the methyl group in the substance are not equivalent. The isomers of the cobalt(III) complex with the asymmetric tetradentate SS-EDDIV ligand were prepared and separated; their characteristics are given. The absolute configuration of two of the five theoretically feasible isomers was determined based on their electronic absorption spectra and circular dichroism data.

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