Novel cinchona carbamate selectors with complementary enantioseparation characteristics for N-acylated amino acids
| Autor: | Wolfgang Lindner, Alessandro Casnati, Norbert M. Maier, Karl Heinz Krawinkler, Rocco Ungaro, Francesco Sansone |
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| Rok vydání: | 2003 |
| Předmět: |
Carbamate
Magnetic Resonance Spectroscopy Stereochemistry medicine.medical_treatment Molecular Conformation Cinchona Cooperativity Catalysis Analytical Chemistry Drug Discovery Calixarene medicine Polycyclic Compounds Amino Acids Spectroscopy Pharmacology chemistry.chemical_classification Chromatography biology Chemistry Elution Organic Chemistry Hydrogen Bonding Stereoisomerism biology.organism_classification Amino acid Models Chemical Carbamates Chloroform Calixarenes Enantiomer Chirality (chemistry) Chromatography Liquid |
| Zdroj: | Chirality. 15:S17-S29 |
| ISSN: | 1520-636X 0899-0042 |
| DOI: | 10.1002/chir.10257 |
| Popis: | The synthesis and chromatographic evaluation of the enantiomer separation capabilities of covalently immobilized calix[4]arene-cinchona carbamate hybrid type receptors derived from quinine (QN) and its corresponding C9-epimer (eQN) in different solvents are reported. The receptors display complementary enantiomer separation profiles in terms of elution order, chiral substrate specificity, and mobile phase characteristics, indicating the existence of two distinct chiral recognition mechanisms. The QN-derived receptor binds the (S)-enantiomers of N-acylated amino acids more strongly, shows preferential recognition of open-chained amino acids, and superior enantioselectivity in polar media such as methanol/acetic acid. In contrast, the eQN congener preferentially recognizes the corresponding (R)-enantiomers, displays good enantioselectivity (α up to 1.74) for cyclic amino acids, and enhanced stereodiscriminating properties in apolar mobile phases, e.g., chloroform/acetic acid. A comparison of the enantiomer separation profiles with those of the corresponding QN and eQN tert-butyl carbamate congeners indicates no significant level of cooperativity between the calix[4]arene module and the cinchona units in terms of overall chiral recognition, most probably as a consequence of residual conformational flexibility of the calixarene module and the carbamate linkage. Chirality 15:S17–S29, 2003. © 2003 Wiley-Liss, Inc. |
| Databáze: | OpenAIRE |
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