作者
Claudia Kahle, Ralph Deubner, Curd Schollmayer, Josef Scheiber, Knut Baumann, Ulrike Holzgrabe
发表日期
2005/4
来源
European journal of organic chemistry
卷号
2005
期号
8
页码范围
1578-1589
出版商
WILEY‐VCH Verlag
简介
Cyclodextrins (CDs) are often used to separate the enantiomers of chiral drugs by HPLC, GC, and capillary electrophoresis (CE). For dipeptides containing one aromatic amino acid, a reversal of the migration order is observed in CE upon increasing the pH value of the background electrolyte from 2.5 to 3.5. In order to understand the mechanism of chiral recognition of this phenomenon, NMR experiments, namely complexation‐induced chemical shifts (CICS) and ROESY, were performed. Comparing the CICSs obtained for the pairs Diac‐β‐CD/Ala‐Phe and HDAS‐β‐CD/Ala‐Phe and Diac‐β‐CD/Ala‐Tyr and HDAS‐β‐CD/Ala‐Tyr revealed very small changes, thereby indicating a rather weak interaction of the respective guest molecules with their host. The CICS for β‐CD and HS‐β‐CD confirmed an inclusion of the aromatic moiety into the CD cavity. It is shown that, at pH 2.5, the D,D‐enantiomer of Ala‐Tyr …
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