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Stereoisomeric separation of pharmaceutical compounds using CE with a chiral crown ether
Author(s) -
Zhou Lili,
Lin Zhihao,
Reamer Robert A.,
Mao Bing,
Ge Zhihong
Publication year - 2007
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.200600788
Subject(s) - crown ether , chemistry , enantiomer , ether , epimer , chiral derivatizing agent , chirality (physics) , 18 crown 6 , organic chemistry , stereochemistry , chiral column chromatography , molecule , ion , chiral symmetry breaking , physics , quantum mechanics , nambu–jona lasinio model , quark
Optical pure (+)‐(18‐crown‐6)‐2,3,11,12‐tetracarboxylic acid, a chiral crown ether, was successfully used as a chiral selector for the stereoisomeric separation of numerous real pharmaceutical compounds. Both practical and mechanistic aspects were described. Effects of chiral selector concentration under different pH values of BGE were discussed. Chiral recognition for the enantiomeric compounds with (+)‐(18‐crown‐6)‐2,3,11,12‐tetracarboxylic acid was investigated through model compounds using CE and infrared spectroscopic techniques. Relations between the enantioselectivity of the chiral crown ether and the structural features of the studied compounds were also investigated. Unusual resolutions of compound‐p and its enantiomer as well as compound‐o and its 2b epimer were described. These compounds contained only tertiary amine, believed to be nonbinding with crown ethers in general. The possible mechanisms for the interaction between compound‐o and the chiral crown ether were investigated using CE, electrospray MS (ESI‐MS), and proton ( 1 H) NMR spectroscopy. All experiments provided clear evidence that binding between compound‐o and the chiral crown ether had occurred. ESI‐MS spectra indicated that the complexes had a 1:1 stoichiometric ratio. The advantages and disadvantages of using chiral crown ether for stereoisomeric separations were compared with those using sulfated CDs.