Synthesis of 7,6-Spirocyclic Imine with Butenolide Ring Provides Evidence for the Relative Configuration of Marine Toxin 13-desMe Spirolide C

2019 ◽  
Vol 21 (22) ◽  
pp. 8970-8975 ◽  
Author(s):  
Kou Minamino ◽  
Michio Murata ◽  
Hiroshi Tsuchikawa
Keyword(s):  
Relative Configuration ◽  
Marine Toxin

Synthesis and Relative Configuration of the Sugar Part of a Marine Toxin Polycavernoside-A

1995 ◽  
Vol 24 (3) ◽  
pp. 191-192 ◽  
Author(s):  
Kenshu Fujiwara ◽  
Seiji Amano ◽  
Akio Murai
Keyword(s):  
Relative Configuration ◽  
Marine Toxin ◽  
Polycavernoside A

ChemInform Abstract: Relative Configuration of a Marine Toxin Polycavernoside-A.

ChemInform ◽  
2010 ◽  
Vol 27 (5) ◽  
pp. no-no
Author(s):  
K. FUJIWARA ◽  
S. AMANO ◽  
A. MURAI
Keyword(s):  
Relative Configuration ◽  
Marine Toxin ◽  
Polycavernoside A

Relative Configuration of a Marine Toxin Polycavernoside-A

1995 ◽  
Vol 24 (9) ◽  
pp. 855-856 ◽  
Author(s):  
Kenshu Fujiwara ◽  
Seiji Amano ◽  
Akio Murai
Keyword(s):  
Relative Configuration ◽  
Marine Toxin ◽  
Polycavernoside A

Study of permeability of the marine toxin azaspiracid-1 over in vitro human intestinal model

Planta Medica ◽  
2016 ◽  
Vol 81 (S 01) ◽  
pp. S1-S381
Author(s):  
P Abal ◽  
MC Louzao ◽  
M Fraga ◽  
N Vilariño ◽  
S Ferreiro ◽  
...  
Keyword(s):  
Marine Toxin

Diastereoselective Reduction of Selected α-substituted β-keto Esters and the Assignment of the Relative Configuration by 1H-NMR Spectroscopy

2020 ◽  
Vol 07 ◽  
Author(s):  
Christian Trapp ◽  
Corinna Schuster ◽  
Chris Drewniok ◽  
Dieter Greif ◽  
Martin Hofrichter
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
1H Nmr Spectroscopy ◽  
Selective Reduction ◽  
Reducing Agents ◽  
Relative Configuration ◽  
Curtius Rearrangement ◽  
Keto Esters ◽  
Hydroxy Esters ◽  
Diastereoselective Reduction

Background:: Chiral β-hydroxy esters and α-substituted β-hydroxy esters represent versatile building blocks for pheromones, β-lactam antibiotics and 1,2- or 1,3-aminoalcohols. Objective:: Synthesis of versatile α-substituted β-keto esters and their diastereoselective reduction to the corresponding syn- or anti-α-substituted β-hydroxy esters. Assignment of the relative configuration by NMR-spectroscopy after a CURTIUS rearrangement of α-substituted β-keto esters to 4-substituted 5-methyloxazolidin-2-ones. Method:: Diastereoselective reduction was achieved by using different LEWIS acids (zinc, titanium and cerium) in combination with complex borohydrides as reducing agents. Assignment of the relative configuration was verified by 1H-NMR spectroscopy after CURTIUS-rearrangement of α-substituted β-hydroxy esters to 4-substituted 5-methyloxazolidin-2-ones. Results:: For the syn-selective reduction, titanium tetrachloride (TiCl4) in combination with a pyridine-borane complex (py BH3) led to diastereoselectivities up to 99% dr. High anti-selective reduction was achieved by using cerium trichloride (CeCl3) and steric hindered reducing agents such as lithium triethylborohydride (LiEt3BH). After CURTIUS-rearrangement of each α-substituted β-hydroxy ester to the corresponding 4-substituted 5-methyloxazolidin-2-one, the relative configuration was confirmed by 1H NMR-spectroscopy. Conclusion:: We have expanded the procedure of LEWIS acid-mediated diastereoselective reduction to bulky α-substituents such as the isopropyl group and the electron withdrawing phenyl ring.

Sterically Crowded Heterocycles. VI. Relative Configuration of Diastereoisomeric (Z)-1,3-Diphenyl-3-(5-methyl-2-phenylimidazo[1,2-a]pyridin-3-yl)prop-2-en-1-ols

1996 ◽  
Vol 61 (9) ◽  
pp. 1380-1385 ◽  
Author(s):  
Jan Čejka ◽  
Richard Kubík ◽  
Bohumil Kratochvíl ◽  
Josef Kuthan
Keyword(s):  
Preparative Separation ◽  
Orthorhombic Space Group ◽  
Relative Configuration ◽  
Space Group ◽  
X Ray

Relative configuration of the titled racemic compounds 1a and 1b has been elucidated on the basis of a complete X-ray structure determined for the higher melting diastereoisomer. The compound 1a crystallizes in the orthorhombic space group P21212, a = 15.610(3) Å, b = 18.634(4) Å, c = 7.5672(7) Å, V = 2201.1(6) Å3, Z = 4. Preparative separation of both diastereoisomers is reported.

Overview of Marine Toxin Research in Cuba

2003 ◽  
Vol 9 (2) ◽  
pp. 117-136 ◽  
Author(s):  
C. Alvarez ◽  
M. Tejuca ◽  
I.F. Pazos ◽  
M.E. Lanio ◽  
A. Garateix ◽  
...  
Keyword(s):  
Marine Toxin

Diterpenes from Euphorbia myrsinites and Their Anti-inflammatory Property

Planta Medica ◽  
2021 ◽  
Author(s):  
Laura Grauso ◽  
Bruna de Falco ◽  
Giuseppe Lucariello ◽  
Raffaele Capasso ◽  
Virginia Lanzotti
Keyword(s):  
Folk Medicine ◽  
Phytochemical Analysis ◽  
Spectroscopic Techniques ◽  
Significant Activity ◽  
Relative Configuration ◽  
Drug Candidates ◽  
The Usa ◽  
Anti Inflammatory ◽  
Dose Dependent ◽  
Diterpene Alcohol

Abstract Euphorbia myrsinites is one of the oldest spurges described and used in folk medicine. It is characterized by blue-grey stems similar to myrtle, and it is spread in the Mediterranean region, Asia, and the USA. Chemical analysis of E. myrsinites collected in Turkey afforded the isolation of 4 diterpenes based on the so-called myrsinane skeleton being tetraesters of the tetracyclic diterpene alcohol myrsinol. In this study, the phytochemical analysis of this species collected in Italy has been undertaken to afford the isolation of a new atisane diterpene, named myrsatisane, 3 ingenol derivatives, along with the 4 tetraester derivatives previously found. A triterpene compound based on the euphane skeleton has also been isolated. Structural elucidation of the new myrsatisane was based on spectroscopic techniques, including HR-MS and 1- and 2-dimensional NMR experiments. Its relative configuration was determined by NOE correlations, while absolute stereochemistry was obtained by quantum-mechanical DFT studies. While diterpenes with the atisane skeleton are relatively common in Euphorbia species, this is the first report of an atisane diterpene from E. myrsinites. All the isolated terpenes were tested for anti-inflammatory activity on J774A.1 macrophages stimulated with lipopolysaccharide by evaluation of nitrite and pro-inflammatory cytokine Il-1β levels. Among tested compounds, the 3 ingenol diterpenes exhibited a dose-dependent (0.001 – 3 µM) significant activity, thus showing their potential as anti-inflammatory drug candidates.

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