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Enantioselective anion exchangers based on cinchona alkaloid‐derived carbamates: Influence of C 8 /C 9 stereochemistry on chiral recognition
Author(s) -
Maier Norbert M.,
Nicoletti Lorenzo,
Lämmerhofer Michael,
Lindner Wolfgang
Publication year - 1999
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/(sici)1520-636x(1999)11:7<522::aid-chir2>3.0.co;2-u
Subject(s) - chemistry , stereocenter , cinchona , quinidine , diastereomer , steric effects , enantioselective synthesis , cinchona alkaloids , chirality (physics) , chiral derivatizing agent , hydrogen bond , stereochemistry , enantiomer , chiral column chromatography , organic chemistry , molecule , catalysis , medicine , nambu–jona lasinio model , chiral symmetry breaking , physics , quantum mechanics , quark , pharmacology
Four diastereomeric chiral stationary phases (CSPs) based on quinine, quinidine, epiquinine, and epiquinidine tert ‐butyl carbamate selectors were synthesized and evaluated under ion exchange HPLC conditions with a set of racemic N‐acylated and N‐oxycarbonylated α‐amino acids as selectands. The enantioseparation potential of quinine‐ and quinidine‐derived CSPs proved to be far superior to that of their C 9 ‐epimeric congeners. The absolute configuration of C 9 stereogenic center of the cinchonan backbone of these selectors was identified as the structural feature controlling the elution order. Guided by an X‐ray structure of a most favorable selector–selectand complex and the observed chromatographic enantioseparation data, a chiral recognition model was advanced. The contributions of ion‐pairing, π–π donor–acceptor, hydrogen bonding and steric interactions were established as crucial factors. Chirality 11:522–528, 1999. © 1999 Wiley‐Liss, Inc.