Determination of the Rotational Energy Barrier of Planar-Chiral Cyclophanes Using Dynamic Enantioselective Gas Chromatography and Computer Simulation

✍ Scribed by Hochmuth, Detlev H. ;König, Wilfried A.

• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 532 KB
• Volume: 1996
• Category: Article
• ISSN: 0947-3440
• DOI: 10.1002/jlac.199619960613

✦ Synopsis

Abstract

We synthesized numerous new monosubstituted dioxa[11]‐paracyclophanes, which are planar‐chiral atropisomers due to the hindered rotation of the bridge about the aromatic plane, and we were able to resolve the enantiomers of these compounds by enantioselective gas chromatography with selectively modified cyclodextrins as chiral stationary phases in polysiloxane solution. As a consequence of the competition between enantiomeric resolution and enantiomerization (interconversion) during the gas chromatographic process, coalescence phenomena or formation of plateaus between the peaks of both enantiomers are observable. The combination of these dynamic gas chromatographic investigations with computer simulation of elution profiles allows the facile and precise determination of the energy barrier of the enantiomerization reaction and the elucidation of the influence of substituents on the energy barrier.