And atropisomers

It is in the study of this phenomenon where two-dimensional GC offers by far the most superior method of analysis. The use of chiral selector stationary phases, in particular modified cyclodextrin types, allows apolar primary and atropisomer selective secondary separation. Reported two-dimensional methods have been successful... 

In looking at vancomycin and teicoplanin, the hydroxyls are but one choice for functionalization reactions. Each natural product also possesses electron-rich arenes, which may be platforms for electrophilic aromatic substitution reactions. In parallel studies of enantioselective and atropisomer-selective bromination reactions [161-164], we were gaining experience with catalyst-controlled bromina-tions, and we wondered whether these might be extended to site-selective reactions. We speculated that an appropriately positioned Lewis base, such as a dimethyl amide unit, could assist in the delivery of electrophilic bromine... 

Stereoisomers Compounds that have the same molecular formula, the same connectivity of their atoms, but a different orientation of their atoms in space. The term "stereoisomer"includes cis,trans isomers in cycloalkanes and alkenes as well as enantiomers, diastereomers, meso compounds, and atropisomers. Conformational isomers are also stereoisomers, whether they are isolable or not. 

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