Helical molecules in organic chemistry

Racemic thalidomide is chromatographically separated on optically active polyamide giving both enantiomers After ip administration only the S-(-)-enantiomer is teratogenic on SWS mice and Natal rats

Chromatographische Racemattrennung von Thalidomid und teratogene Wirkung der Enantiomere

A number of racemates can be resolved into optically pure enantiomers by chromatography on optically active adsorbents. Synthetic polymers with optically active amide, amino acid, and crown ether groups, natural products such as starch and cellulose, and also microcrystalline triacetylcellulose are suitable for this purpose. Racemates can also be resolved by gas chromatography on optically active stationary phases.

Chromatographic Resolution of Racemates. New analytical methods (17)

Racemization, Enantiomerization, Diastereomerization, and Epimerization - Their Meaning and Pharmacological Significance

Contribution of preparative chromatographic resolution to the investigation of chiral phenomena

Enantiomeric diaziridines have been partially separated by chromatography on triacetlycellulose. (−)-2, (+)-4, and (−)-4 were obtained almost pure, enantiomeric purities (Table 1) being measured by 1H NMR in the presence of optically active additives. The same procedure was tested for monitoring racemizations (Table 2) which were also studied, with higher accuracy, by polarimetry. The barriers to nitrogen inversion, converting the trans-diaziridines 2and4into cis-intermediates, are compared with known ΔG≠ values.



Protonenresonanz-Untersuchugen zur Inversion am dreibindigen Stickstoffatom, 6. Praparative Trennungen enantiomerer Diaziridine durch Flussigkeits-Chromatographie an Triacetylcellulose. Verfolgung der Racemisierungen mittels Polarimetrie und 1H-NMR



Enantiomere Diaziridine liesen sich durch Chromatographie an Triacetylcellulose anreichern. (−)-2, (+)-4 und (−)-4 wurden fast rein erhalten, wobei die enantiomeren Reinheiten (Tab. 1) mittels 1H-NMR in Gegenwart optisch aktiver Zusatze bestimmt wurden. Dasselbe Verfahren wurde im Hinblick auf die Verfolgung von Racemisierungen (Tab.2) erprobt, welche mit hoherer Genauigkeit auserdem mittels Polarimetrie studiert wurden. Die Schwellen der Stickstoff-Inversion, welche die trans-Diaziridine 2 und 4 in cis-Zwischenstufen uberfuhrt, werden mit bekannten ΔG≠-Werten verglichen.

Proton Magnetic Resonance Investigation of Inversion at Tervalent Nitrogen, 6. Preparative Separations of Enantiomeric Diaziridines by Liquid Chromatography on Triacetylcellulose. Racemizations Monitored by Polarimetry and by 1H NMR

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Proton Magnetic Resonance Investigation of Inversion at Tervalent Nitrogen, 6. Preparative Separations of Enantiomeric Diaziridines by Liquid Chromatography on Triacetylcellulose. Racemizations Monitored by Polarimetry and by 1H NMR