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Chiral discrimination of the analgesic cizolirtine by using cyclodextrins: A 1 H NMR study on the solution structures of their host–guest complexes
Author(s) -
Redondo Jordi,
Blázquez Miguel A.,
Torrens Antoni
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)11:9<694::aid-chir5>3.0.co;2-w
Subject(s) - chemistry , enantiomer , diastereomer , cyclodextrin , stereochemistry , molecule , supramolecular chemistry , enantioselective synthesis , substrate (aquarium) , molecular recognition , stereoisomerism , organic chemistry , catalysis , oceanography , geology
Abstract The use of four cyclodextrins (three native and one β‐CD derivative) as NMR chiral solvating agents to resolve the enantiomers of (±)‐cizolirtine, 1 , and its chemical precursor (the carbinol, (±)‐ 2 ), was investigated. The best enantiodiscrimination occurred when β‐cyclodextrin was used. ROESY experiments were performed to qualitatively ascertain the most probable host–guest structures in D 2 O solution, and the binding features found were explained in terms of spatial fitting of the guest molecules into the macrocyclic cavities. No geometrical differences were noted between the two diastereomeric complexes formed by a cyclodextrin and a racemic substrate, so the magnetic nonequivalence induced on guest protons by the enantioselective binding had to be explained as a result of subtle disparities in the orientation and/or the conformational state of the complexed enantiomers. Chirality 11:694–700, 1999. © 1999 Wiley‐Liss, Inc.