Notizen: The Absolute Configuration of Julifloridine

The preparation and separation into diastereomers of tbutyl-phenyl-phosphinic acid (—)-menthyl ester (1a) is reported. The diastereomeric purity as well as the absolute configuration at phosphorus of 1 a can be deduced from the detailed analysis of the 1H NMR spectra of samples of 1a differing in their diastereomer ratios.

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Determination of Absolute Stereochemistry of Natural Alicyclic Glycosides by 1H NMR Spectroscopy without Application of Chiral Reagents – An Indication

Natural Product Communications ◽

10.1177/1934578x1100600520 ◽

2011 ◽

Vol 6 (5) ◽

pp. 1934578X1100600 ◽

Cited By ~ 1

Author(s):

Tatyana N. Makarieva ◽

Larisa K. Shubina ◽

Alla G. Guzii ◽

Natalya V. Ivanchina ◽

Vladimir A. Denisenko ◽

...

Keyword(s):

Nmr Spectroscopy ◽

1H Nmr ◽

Absolute Configuration ◽

1H Nmr Spectroscopy ◽

Nmr Spectra ◽

H Nmr ◽

Steroid Glycosides ◽

The Absolute ◽

Absolute Stereochemistry

A study has been made of the 1H NMR spectra of peracetylated β-glucopyranosides and α-arabinopyranosides obtained by reaction of D- and L-glucoses, and L- and D-arabinoses with either ( R)- or ( S)-2-octanols. The obtained and literature data show that 1H NMR spectra may be used to determine the absolute configuration of the aglycone moieties of some alicyclic glycosides without the need to synthesize derivatives with chiral reagents, as long as the absolute configuration of their monosaccharide moiety is known or vice versa. Spectra of marine steroid glycosides and their acetates containing glycosylated side chains as alicyclic fragments were also examined. It was shown that analysis of 1H NMR spectra for the determination of the absolute configuration is more applicable in the cases when glycosides have the same substitution in the D-ring of the aglycone moiety.

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The First Isolation Of A Phlegmacin Type Pigment From The Ascomycete Xylaria Euglossa

Zeitschrift für Naturforschung B ◽

10.1515/znb-2005-0317 ◽

2005 ◽

Vol 60 (3) ◽

pp. 333-336 ◽

Cited By ~ 7

Author(s):

Xing-Na Wang ◽

Ren-Xiang Tan ◽

Fei Wang ◽

Wolfgang Steglich ◽

Ji-Kai Liu

Keyword(s):

Methyl Ether ◽

Absolute Configuration ◽

Spectroscopic Data ◽

Nmr Spectra ◽

Fruiting Bodies ◽

H Nmr ◽

The Absolute ◽

Fungal Pigments

A new pigment, phlegmacin A 8,8’-di-O-methyl ether (1), was isolated from fruiting bodies of Xylaria euglossa (Ascomycota) along with the known fungal pigments (S)-torosachrysone-8-O-methyl ether (2) and emodin-6,8-di-O-methyl ether (3). The structure of compound 1 was established on the basis of its spectroscopic data and the absolute configuration determined as P and 3’S by comparing the CD and 1H NMR spectra of 1 with those of the phlegmacins 4 and 5. Compound 1 represents the first phlegmacin type pigment isolated from the ascomycete

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Preparation and absolute configuration at C(20) of 21-nor-5α-chol-22-en-24→20-olide derivatives

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19810917 ◽

1981 ◽

Vol 46 (4) ◽

pp. 917-925 ◽

Cited By ~ 2

Author(s):

Vladimír Pouzar ◽

Miroslav Havel

Keyword(s):

Absolute Configuration ◽

Nmr Spectra ◽

Lithium Salt ◽

H Nmr ◽

Chemical Correlation ◽

Unsaturated Lactones

Reaction of the aldehyde I with the lithium salt of 1-(2-tetrahydropyranyloxy)-2-propyne yielded the compounds II and IV. From the compound II the lactone XII was prepared via the intermediates III and X, the lactone XVIII was prepared from the substance IV via the intermediates V and XVI. The unsaturated lactones XII and XVIII were also prepared by sulfenylation and dehydrosulfenylation of the saturated lactones XIII and XIX. Based on chemical correlation and 1H-NMR spectra analyses of the compounds II and IV, the lactone XII was assigned the 20R-configuration whereas the lactone XVIII was allotted the 20S-configuration.

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A New Bisabolene from Stevia tomentosa

Natural Product Communications ◽

10.1177/1934578x1100600903 ◽

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).

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Δ-Sym-cis and Δ-unsym-cis-carbonato-(2S,2'S)-2,2'-ethylene-bis(2-amino-3-methylbutanoato)cabaltate(III) isomers

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19871488 ◽

1987 ◽

Vol 52 (6) ◽

pp. 1488-1493 ◽

Cited By ~ 1

Author(s):

František Jursík ◽

Samir Abdel-Moez

Keyword(s):

Acid Hydrolysis ◽

Absolute Configuration ◽

Nmr Spectra ◽

Tetradentate Ligand ◽

Steric Crowding ◽

The Absolute ◽

Kinetic Effects ◽

Hydrolysis Of ◽

C Nmr

The tetradentate ligand (2S,2'S)-2,2'-ethylene-bis(2-amino-3-methylbutanoato) (eddval) is coordinated in the [Co(eddval)CO3]- anion to give 88% of Δ-sym-cis and 12% of Δ-unsym-cis isomers. The stereospecific formation of the Δ-sym-cis isomer is explained by steric crowding in the Λ-sym-cis isomer. The predominance of the sym-cis isomer indicates that the synthesis is also influenced by kinetic effects. These are particularly pronounced in the case of the Δ-unsym-cis isomer which for steric reasons is thermodynamically less stable than the Λ-unsym-cis isomer. The secondary nitrogen atoms in the Δ-sym-cis isomer are of the R configuration whereas in the Δ-unsym-cis isomer they have configuration R and S. The absolute configuration of the isomers has been determined from their absorption, CD, 1H and 13C NMR spectra. Acid hydrolysis of Δ-sym-cis-[Co(eddval)CO3]- proceeds with retention of configuration to give the Δ-[Co(eddval)(H2O)2]+ isomer.

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The assignment of the configuration for α-hydroxy acid esters using a CEC strategy

Organic & Biomolecular Chemistry ◽

10.1039/c6ob00927a ◽

2016 ◽

Vol 14 (23) ◽

pp. 5258-5262 ◽

Cited By ~ 3

Author(s):

Ruixue Peng ◽

Lili Lin ◽

Yuheng Zhang ◽

Wangbin Wu ◽

Yan Lu ◽

...

Keyword(s):

Absolute Configuration ◽

Hydroxy Acid ◽

H Nmr ◽

Nmr Method ◽

The Absolute ◽

Acid Esters

A simple and efficient 1H NMR method for determining the absolute configuration of chiral α-hydroxy acid esters using a CEC strategy with a chiral N,N′-dioxide-scandium(iii) complex was developed.

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Structure of isosilerolide, relative and absolute configuration of silerolide and lasolide - Sesquiterpenic lactones of new stereoisomeric type of eudesmanolides

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19860903 ◽

1986 ◽

Vol 51 (4) ◽

pp. 903-929 ◽

Cited By ~ 16

Author(s):

Miroslav Holub ◽

Miloš Buděšínský ◽

Zdenka Smítalová ◽

David Šaman ◽

Urszula Rychłewska

Keyword(s):

Absolute Configuration ◽

X Ray Diffraction ◽

X Ray ◽

H Nmr ◽

Nmr Data ◽

Chemical Correlation ◽

The Absolute

On the basis of spectroscopic, particularly 1H NMR data, isosilerolide was assigned structure I, including the absolute configuration. The structure was confirmed by X-ray diffraction. Isosilerolide represents a new stereoisomeric type of natural eudesmanolides, characterized as 5βH, 6αH, 7αH, 10αCH3-eudesman-6,12-olide. As shown by the chemical correlation of isosilerolide (I) with silerolide (III) and lasolide (X), the latter two natural lactones belong to this stereoisomeric group of eudesmanolides. Analysis of models and 1H NMR data shows that structures of some eudesman-6,12-olides, published by other authors, should be corrected.

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Sesquiterpenic lactones of Inula aschersoniana JANKA var. aschersoniana species

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19901562 ◽

1990 ◽

Vol 55 (6) ◽

pp. 1562-1567 ◽

Cited By ~ 10

Author(s):

Ełżbieta Błoszyk ◽

Miloš Buděšínský ◽

Włodzimierz M. Daniewski ◽

Eva Pešková ◽

Bohdan Drożdż ◽

...

Keyword(s):

Absolute Configuration ◽

Cd Spectroscopy ◽

H Nmr ◽

Aerial Parts ◽

The Absolute

Aerial parts of species Inula aschersoniana JANKA var. aschersoniana have been shown to contain parthenolide (I), costunolide diepoxide (III) and the hitherto undescribed inusoniolide (IV) whose structure, including the absolute configuration, was determined using 1H NMR and CD spectroscopy.

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A Novel Acylated Anthocyanin with a Linear Trisaccharide from Flowers of Convolvulus althaeoides

Natural Product Communications ◽

10.1177/1934578x1501001140 ◽

2015 ◽

Vol 10 (11) ◽

pp. 1934578X1501001 ◽

Cited By ~ 1

Author(s):

Luis Cabrita

Keyword(s):

Absolute Configuration ◽

Complete Characterization ◽

H Nmr ◽

Chromatographic Techniques ◽

Maldi Tof ◽

The Absolute

An acylated anthocyanin trioside was isolated from pink flowers of Convolvulus althaeoides using a combination of chromatographic techniques. On the basis of MS (MALDI-TOF) and NMR (1H NMR, 1H-1H COSY, 1D TOCSY, HSQC, HMBC, 13C CAPT) its structure was determined as cyanidin 3- O-[6- O-(4- O-(6- O-( E-caffeoyl)-β-D-glucopyranosyl)-α-L-rhamnopyranosyl)-β-D-glucopyranoside]-5- O-β-D-glucopyranoside. The absolute configuration of the aldose enantiomer moieties was determined from the separation of the corresponding thiazolidine diastereoisomer derivatives by HPLC-DAD. This is a novel trisaccharide within the flavonoids, and the first complete characterization of a linear glucosyl-rhamnosyl-glucoside (4′-glucosylrutinoside) within the anthocyanins. Whilst acylation of rhamnose moieties in position 4 is quite common, the occurrence in anthocyanins of a glycosylated rhamnose is a unique trait. Although many complex anthocyanins have been found amongst the Convolvulaceae, the genus Convolvulus had not yet been surveyed for anthocyanins and thus this account could be of significance within the current chemotaxonomy of this family.

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