On the diastereomeric purity of the D (−)-(2R )-ampicillin

2019 ◽  
Vol 58 (2) ◽  
pp. 191-197
Author(s):  
Jerzy Sitkowski ◽  
Beata Naumczuk ◽  
Wojciech Bocian ◽  
Elżbieta Bednarek ◽  
Lech Kozerski
Keyword(s):  
Diastereomeric Purity

Synthesis of (3S,4S)-4-amino-3-hydroxy-6-methylheptanoic acid derivatives. Analysis of diastereomeric purity

1978 ◽  
Vol 43 (18) ◽  
pp. 3624-3626 ◽  
Author(s):  
Daniel H. Rich ◽  
Eric T. Sun ◽  
Amrit S. Boparai
Keyword(s):  
Diastereomeric Purity

scholarly journals Kinetic Separation of cis-and trans-Limonene Epoxide: Reaction of Diastereomeric Mixture of Limonene Oxides with Secondary Amine and Carbamate

2021 ◽  
Vol 33 (11) ◽  
pp. 2667-2670
Author(s):  
M.M. El Hammoumi ◽  
L. Ait Said ◽  
A. El Bachiri ◽  
M. Khoukhi
Keyword(s):  
Trans Isomer ◽  
Secondary Amine ◽  
Ethyl Carbamate ◽  
Epoxide Ring ◽  
Diastereomeric Mixture ◽  
Limonene Oxide ◽  
Cis And Trans ◽  
Hydrolysis Of ◽  
Diastereomeric Purity ◽  
Kinetic Separation

A simple kinetic separation of (1:1) diastereomeric mixture of limonene oxides was used to purify cis-and trans-diastereomers of (R)-(+)-limonene oxide. The epoxide ring of trans-isomer was selectively opened by (R)-N-methyl-(α-methyl-benzyl)amine. This secondary nucleophilic amine left cis-limonene oxide largely unreacted and was obtained up to 90% yield. In a diverse way, (R)-N-(α-methylbenzyl) ethyl carbamate, selectively catalyze hydrolysis of cis-limonene oxide to 1,2-limonene diol leaving trans-limonene oxide largely unreacted. The unreacted trans-limonene oxide was recovered in up to 75% yield. HPLC and NMR analyses were used to demonstrate that the isolation of cis-and trans-diastereomers of (R)-(+)-limonene oxide has shown that > 98% were pure. As a result, depending on the realization of the secondary amine or carbamate in the presence of water, either cis-or trans-limonene oxide may be obtained in high diastereomeric purity.

A Rapid and Sensitive LC Method for Determination of Diastereomeric Purity of Tenofovir Alafenamide

2014 ◽  
Vol 77 (19-20) ◽  
pp. 1399-1403
Author(s):  
Mingxing Hu ◽  
Qi Wang ◽  
Xiuying Ma ◽  
Chao Yang ◽  
Hongbao Sun ◽  
...  
Keyword(s):  
Tenofovir Alafenamide ◽  
Diastereomeric Purity

Enzymatic Assignment of Diastereomeric Purity of Stereodefined Phosphorothioate Oligonucleotides

1999 ◽  
Vol 9 (2) ◽  
pp. 171-181 ◽  
Author(s):  
MARIA KOZIOŁKIEWICZ ◽  
ALINA OWCZAREK ◽  
EDYTA GENDASZEWSKA
Keyword(s):  
Diastereomeric Purity

High yield preparation of a novel tetrakis[ruthenium tris(bipyridine)]calix[6]arene derivative with good diastereomeric purity

1998 ◽  
Vol 9 (22) ◽  
pp. 4089-4097 ◽  
Author(s):  
Dusan Hesek ◽  
Yoshihisa Inoue ◽  
Simon R.L. Everitt ◽  
Mieko Kunieda ◽  
Hitoshi Ishida ◽  
...  
Keyword(s):  
High Yield ◽  
Arene Derivative ◽  
Diastereomeric Purity

Stereoselective Synthesis of 2-Substituted Pyrrolidines

2000 ◽  
Vol 65 (5) ◽  
pp. 816-828 ◽  
Author(s):  
Sandrine Deloisy ◽  
Heiko Tietgen ◽  
Horst Kunz
Keyword(s):  
Stereoselective Synthesis ◽  
Diastereomeric Purity

Using O-pivaloyl protected D-galactopyranosylamine and D-arabinopyranosylamine, (S) or (R) configured α-substituted homoallylamines are synthesized with high diastereoselectivity by reaction of the corresponding aldimines with allyltributylstannane. Electrophile-induced endo-trig-cyclization of these N-glycosylhomoallylamines gave the 2-substituted pyrrolidines of high diastereomeric purity.

1H—NMR-spektroskopische Bestimmung der diastereomeren Reinheit und der absoluten Konfiguration am Phosphoratom von tButyl-phenyl-phosphinsäure-(—)-menthylester / Determination of the Diastereomeric Purity and the Absolute Configuration at Phosphorus of tButyl-phenyl-phosphinic Acid (—)-Menthyl Ester by Means of 1H NMR Spectroscopy

1977 ◽  
Vol 32 (5) ◽  
pp. 589-593 ◽  
Author(s):  
Reiner Luckenbach ◽  
Hans-H. Bechtolsheimer
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
Absolute Configuration ◽  
1H Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Phosphinic Acid ◽  
H Nmr ◽  
The Absolute ◽  
Diastereomeric Purity

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.

scholarly journals Ancistrotectoquinones A and B, the First Quinoid Naphthylisoquinoline Alkaloids, from the Chinese Liana Ancistrocladus tectorius

2016 ◽  
Vol 11 (7) ◽  
pp. 1934578X1601100
Author(s):  
Gerhard Bringmann ◽  
Minjuan Xu ◽  
Raina Seupel ◽  
Doris Feineis ◽  
Jun Wu
Keyword(s):  
Dft Calculations ◽  
Steric Hindrance ◽  
Time Dependent ◽  
Free Energies ◽  
Biomimetic Oxidation ◽  
Naphthylisoquinoline Alkaloids ◽  
The Absolute ◽  
Diastereomeric Purity

From the leaves and stems of Ancistrocladus tectorius (Ancistrocladaceae) from the Chinese island Hainan, two novel-type 7,3′-coupled naphthylisoquinolines, named ancistrotectoquinones A (4) and B (5), were isolated. They are the first alkaloids with a 1,4-naphthoquinone portion coupled to an isoquinoline moiety. Due to the lowered degree of steric hindrance next to the biaryl axis and for electronic reasons, 4 and 5 occur as pairs of configurationally semi-stable, and, thus slowly interconverting atropo-diastereomers. The Gibbs free energies of activation between the two atropisomers of ancistrotectoquinone A (4a/b) were determined by measuring the time-dependent decrease of diastereomeric purity of freshly separated samples enriched with the M- or P-atropisomer and, computationally, by DFT calculations. The absolute configurations at the biaryl axes of the atropo-diastereomers of 4a/b and 5a/b were assigned by online LC-CD analysis. The stereostructure of 4a/b was further confirmed by its semi-synthesis from the likewise 7,3′-coupled ‘normal' naphthylisoquinoline alkaloid ancistrotectorine (6), by biomimetic oxidation with Fremy's salt.

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