Direct high-performance liquid chromatographic separation of an enantiomeric peptidoleukotriene antagonist and its homologues

Chen, Ted K.; Mills, Robert J.

doi:10.1016/0021-9673(94)85074-7

Cited by 6 publications

(5 citation statements)

References 10 publications

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“…Many literature studies report the successful use of these polymers in the chromatographic separations of numerous chiral solutes. − The effect of additives on the chiral separations of various solutes by use of these polymers was extensively studied. , Reversals in elution orders of some of the racemic compounds were sometimes observed by changing the polymer sorbent. , Wainer and co-workers developed structure−retention correlations by measuring the retention times and selectivities of a series of amides on three amylose-based CSPs. They concluded that the elution order of the solutes depended on the amylose backbone chirality, while the selectivity was affected by the side chain chirality.…”

Section: Introductionmentioning

confidence: 99%

“…11,20 Reversals in elution orders of some of the racemic compounds were sometimes observed by changing the polymer sorbent. 21,22 Wainer and co-workers 23 developed structureretention correlations by measuring the retention times and selectivities of a series of amides on three amylose-based CSPs. They concluded that the elution order of the solutes depended on the amylose backbone chirality, while the selectivity was affected by the side chain chirality.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Backbone and Side Chain on the Molecular Environments of Chiral Cavities in Polysaccharide-Based Biopolymers

2007

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The effects of the backbone and side chain on the molecular environments in the chiral cavities of three commercially important polysaccharide-based chiral sorbents--cellulose tris(3,5-dimethylphenylcarbamate) (CDMPC), amylose tris(3,5-dimethylphenylcarbamate) (ADMPC), and amylose tris[(S)-alpha-methylbenzylcarbamate] (ASMBC)--are studied by attenuated total reflection infrared spectroscopy (ATR-IR), X-ray diffraction (XRD), 13C cross-polarization/magic-angle spinning (CP/MAS) and MAS solid-state NMR, and density functional theory (DFT) modeling. These sorbents are used widely in preparative-scale chiral separations. ATR-IR is used to determine how the H-bonding states of the C=O and NH groups of the polymer depend on the backbone and side chain. The changes in the polymer crystallinity are characterized with XRD. The changes in the polymer helicity and molecular mobility for polymer-coated silica beads (commercially called Chiralcel OD, Chirapak AD, and Chiralpak AS) are probed with 13C CP/MAS and MAS solid-state NMR. The IR wavenumbers and the NMR chemical shifts for the polymer backbone monomers and dimers and the side chains are predicted at the DFT/B3LYP/6-311+g(d,p) level of theory. It is concluded that the molecular environments of the C=O, NH, and phenyl groups show significant differences in intramolecular and intermolecular interactions and in the nanostructures of the chiral cavities of these biopolymers. These results have implications for understanding how the molecular environments of chiral cavities of these polymers affect their molecular recognition mechanisms.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of Backbone and Side Chain on the Molecular Environments of Chiral Cavities in Polysaccharide-Based Biopolymers

2007

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Chiral Separations by Various Techniques

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2010

Chiral Separation Methods for Pharmaceutical and Biotechnological Products

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Chiralpak AD and Chiracel OD columns from Chiral Technology, Inc. have recently gained recognition in the separation of enantiomers of pharmaceutically important compounds [1][2][3][4][5][6][7][8][9]. Both columns have the same dimethylphenyl carbamate functionality; however, AD and OD are an amylose and a cellulose derivative, respectively. The Chiralcel OD column is marketed in both normal-phase mode (OD) and reversed-phase mode (OD-R). However, since the Chiralpak AD column was originally designed by the manufacturer to be used only in the normal-phase mode, there was very little literature on reversed-phase applications of Chiralpak AD columns in the early 1990s. The work presented here demonstrates the superior separations in the reversed-phase mode as compared to the normal-phase mode for Chiralpak AD columns. PHASE-CONVERSION CHIRAL SEPARATIONSThree case studies of separations of pharmaceutical chiral intermediates in the reversed phase are illustrated below. A Chiralpak AD column was converted from the originally designed normal-phase to reversed-phase mode. To convert a chiral column in normal phase to the reversed phase, the column was flushed adequately with 200 proof ethanol at 0.2 mL/min (not exceeding the pressure limit of the column), then equilibrated in an organic and aqueous mixture of the reversed mobile phase. The characteristics of this new reversed-phase application are compared with those of the normal-phase mode. Case Study 1The molecular structures of the first reversed-phase mode separation of pharmaceutical intermediates are as shown in Scheme 1. Compound

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“…Selectivity can be modified by changing mobile phase composition or by switching to a different CSP. 9,10 However, attempts to reduce interferences through mobile phase manipulation often result in a loss of chiral selectivity. Changing CSPs means that the analyst must have a large inventory of expensive CSPs available for method development.…”

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confidence: 99%

“…Although the availability of CSPs for LC has facilitated enantiomeric separations, the low efficiency and poor achiral selectivity of most chiral columns often preclude separation of the analyte from other components in the sample, including either excipients and impurities in drug formulations or metabolites in biological samples. , Selection of internal standards is complicated by the fact that compounds having structures similar to that of the analyte of interest also tend to coelute with the analyte. , Additional active ingredients present in multidrug formulations such as those used to treat hypertension or allergies may also complicate analysis. Selectivity can be modified by changing mobile phase composition or by switching to a different CSP. , However, attempts to reduce interferences through mobile phase manipulation often result in a loss of chiral selectivity. Changing CSPs means that the analyst must have a large inventory of expensive CSPs available for method development. , In addition, optimizing a separation on a number of different CSPs remains a time-consuming trial-and-error process in LC.…”

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confidence: 99%

Coupled Achiral/Chiral Column Techniques in Subcritical Fluid Chromatography for the Separation of Chiral and Nonchiral Compounds

1998

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A multicolumn approach was developed to address the limited achiral selectivity of chiral stationary phases. Groups of structurally related compounds, including beta-blockers and 1,4-benzodiazepines, were separated using coupled achiral/chiral stationary phases under subcritical fluid conditions. The achiral selectivity of amino and cyano stationary phases was used to modify the resolution of compounds on a Chiralcel OD chiral stationary phase by combining the achiral and chiral columns in series. In the case of the benzodiazepines, separation of achiral compounds was performed concurrently with the enantioseparation of chiral molecules. The separation of components of a multidrug cough and cold medication was also demonstrated on a cyano column coupled with a Chiralpak AD chiral stationary phase. The use of modified carbon dioxide eluents eliminated the mobile phase incompatibility problems associated with column coupling in liquid chromatography and incorporated the high efficiency of sub- and supercritical fluid chromatography.

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Direct high-performance liquid chromatographic separation of an enantiomeric peptidoleukotriene antagonist and its homologues

Cited by 6 publications

References 10 publications

Effects of Backbone and Side Chain on the Molecular Environments of Chiral Cavities in Polysaccharide-Based Biopolymers

Effects of Backbone and Side Chain on the Molecular Environments of Chiral Cavities in Polysaccharide-Based Biopolymers

Chiral Separations by Various Techniques

Coupled Achiral/Chiral Column Techniques in Subcritical Fluid Chromatography for the Separation of Chiral and Nonchiral Compounds

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