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High‐performance liquid chromatographic enantioseparation of isoxazoline‐fused 2‐aminocyclopentanecarboxylic acids on a chiral ligand‐exchange stationary phase
Author(s) -
Gecse Zsanett,
Ilisz István,
n Melinda,
Grecsó Nóra,
Fülöp Ferenc,
Agneeswari Rajalingam,
Hyun Myung Ho,
Péter Antal
Publication year - 2013
Publication title -
journal of separation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.72
H-Index - 102
eISSN - 1615-9314
pISSN - 1615-9306
DOI - 10.1002/jssc.201201061
Subject(s) - chemistry , enantiomer , elution , enthalpy , ligand (biochemistry) , chromatography , selectivity , high performance liquid chromatography , chiral ligand , phase (matter) , amino acid , analyte , organic chemistry , enantioselective synthesis , thermodynamics , catalysis , biochemistry , physics , receptor
The application of a chiral ligand‐exchange column for the direct high‐performance liquid chromatographic enantioseparation of unusual β‐amino acids with a sodium N ‐(( R )‐2‐hydroxy‐1‐phenylethyl)‐ N ‐undecylaminoacetate‐Cu(II) complex as chiral selector is reported. The investigated amino acids were isoxazoline‐fused 2‐aminocyclopentanecarboxylic acid analogs. The chromatographic conditions were varied to achieve optimal separation. The effects of temperature were studied at constant mobile phase compositions in the temperature range 5–45°C, and thermodynamic parameters were calculated from plots of ln k or lnα versus 1/ T . Δ(Δ H °) ranged from –2.3 to 2.2 kJ/mol, Δ(Δ S °) from –3.0 to 7.8 J mol −1 K −1 and –Δ(Δ G °) from 0.1 to 1.7 kJ/mol, and both enthalpy‐ and entropy‐controlled enantioseparations were observed. The latter was advantageous with regard to the shorter retention and greater selectivity at high temperature. Some mechanistic aspects of the chiral recognition process are discussed with respect to the structures of the analytes. The sequence of elution of the enantiomers was determined in all cases.