Eluting trace components before major constituents

Perry, John; Rateike, John D.; Szczerba, Ted

doi:10.1016/s0021-9673(01)94410-3

Cited by 51 publications

(18 citation statements)

References 5 publications

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“…Thus, the ()-(S) enantiomers of these analytes were more strongly retained on Chiralpak AS. Because the (+)-(R) enantiomers were preferentially retained on Chiralcel OD [14], and polysaccharide-derived Chiralpak AS and Chiralcel OD have only one enantiomeric form, these observations have the advantage of reversal of elution order, often a desirable feature for determination of enantiomeric purity [18]. The chromatogram obtained from the resolution of racemic cis/trans-CA on Chiralpak AS is shown in Figure 2.…”

Section: Resultsmentioning

confidence: 99%

Separation of the enantiomers of pyrethroic acids and their esters by high-performance liquid chromatography on a polysaccharide-derived chiral stationary phase

Lee

2000

Chromatographia

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Section: Resultsmentioning

confidence: 99%

Separation of the enantiomers of pyrethroic acids and their esters by high-performance liquid chromatography on a polysaccharide-derived chiral stationary phase

Lee

2000

Chromatographia

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“…5,6 We recently reported that poly([2,2¤-bis(methoxymethoxy)-4¤-dodecyloxy-4-biphenylyl]acetylene) (poly(DOBA)) forms a preferred-handed helical conformation together with an excess of one of the axially twisted conformations in the biphenyl pendants, which occurs through the noncovalent interaction with an optically active alcohol ((R)-or (S)-1) both in solution and in the solid state. 7 The induced main-chain helicity and axial chirality can be maintained (or memorized) even after the removal of the chiral alcohol (Scheme 1).…”

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confidence: 99%

“…1,2 Although a large number of CSPs have been developed, 3,4 it is still a challenging issue to switch the elution order of enantiomers without using the CSPs prepared from antipodal chiral materials despite their advantages both in analytical and preparative modes. 5,6 We recently reported that poly([2,2¤-bis(methoxymethoxy)-4¤-dodecyloxy-4-biphenylyl]acetylene) (poly(DOBA)) forms a preferred-handed helical conformation together with an excess of one of the axially twisted conformations in the biphenyl pendants, which occurs through the noncovalent interaction with an optically active alcohol ((R)-or (S)-1) both in solution and in the solid state. 7 The induced main-chain helicity and axial chirality can be maintained (or memorized) even after the removal of the chiral alcohol (Scheme 1).…”

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confidence: 99%

Macromolecular Helicity Induction and Memory in a Poly(biphenylylacetylene) Bearing an Ester Group and Its Application to a Chiral Stationary Phase for High-performance Liquid Chromatography

et al. 2015

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An optically inactive poly(biphenylylacetylene) bearing an ester group at the 4¤-position of the pendants formed a preferredhanded helical conformation and biased axial chirality in the pendants through a noncovalent interaction with a chiral alcohol, both of which were retained (memorized) even after removal of the chiral alcohol. The chiral stationary phase for high-performance liquid chromatography, prepared by coating the polymer with macromolecular helicity memory on silica gel, showed good chiral recognition ability towards various racemates.Direct enantioseparation, using chiral stationary phases (CSPs), by high-performance liquid chromatography (HPLC) has provided a promising method not only for performing microanalysis of chiral compounds but also for obtaining highly-pure enantiomers on the ton scale.1,2 Although a large number of CSPs have been developed, 3,4 it is still a challenging issue to switch the elution order of enantiomers without using the CSPs prepared from antipodal chiral materials despite their advantages both in analytical and preparative modes. 5,6 We recently reported that poly([2,2¤-bis(methoxymethoxy)-4¤-dodecyloxy-4-biphenylyl]acetylene) (poly(DOBA)) forms a preferred-handed helical conformation together with an excess of one of the axially twisted conformations in the biphenyl pendants, which occurs through the noncovalent interaction with an optically active alcohol ((R)-or (S)-1) both in solution and in the solid state. 7 The induced main-chain helicity and axial chirality can be maintained (or memorized) even after the removal of the chiral alcohol (Scheme 1). By using this unusual feature of poly(DOBA), we succeeded in developing a switchable CSP in which the elution order of the enantiomers could be switched at will on the basis of reversible switching and the subsequent memory of macromolecular helicity in poly(DOBA) by sequential treatment with (R)-and (S)-1 in the solid state.However, the chiral recognition ability of poly(DOBA) was not high. In this communication, we designed and synthesized a novel cis-transoidal poly(biphenylylacetylene) derivative bearing an ester group as an effective chiral recognition site instead of an ether group, poly([2,2¤-bis(methoxymethoxy)-4¤-butoxycarbonyl-4-biphenylyl]acetylene) (poly(BCBA)) (Scheme 1), and investigated the effects of the functional group at the 4¤-position of the biphenyl pendant on helicity induction and memory effect, and further the chiral recognition ability as a CSP for HPLC.Poly(BCBA) was synthesized by the polymerization of the corresponding biphenylylacetylene monomer (Scheme S1) with a rhodium catalyst ([Rh(nbd)Cl] 2 ; nbd: norbornadiene) in tetrahydrofuran in the presence of triethylamine in a similar method to that previously reported (Scheme S2).7 The stereoregularity of the obtained polymer was confirmed to be almost completely cis-transoidal by 1

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“…b The chemical shifts were based on the spectrum of racemic DPA (1 mM) in the presence of (+)-18-C-6-TA (1) (0, be precisely determined by chiral HPLC. It should be noted that ChiroSil columns, commercially available in either enantiomeric form have the advantage of the reversing the elution order for enantiomeric purity determinations and preparative applications [19,20]. Since the enantiomers of DPA were separated on the 18-C-6-TA derived CSP by HPLC (Figure 2), it was expected that (+)-IS-C-6-TA used for the preparation of the CSP could be effective for enantiodiscrimination of DPA as a chiral solvating agent (CSA) by NMR spectroscopy.…”

Section: Resultsmentioning

confidence: 99%

Chiral resolution of diphenylalanine by high-performance liquid chromatography on a crown-ether-based chiral stationary phase and by NMR spectroscopy

2003

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KeyWordsColumn liquid chromatography NMR spectroscopy ChTral solvatTng agent 18 Crown 6 tetracarboxylic acid SummaryThe enantTomers of dTphenylalanTne (DPA) were well separated by chiral HPLC and NMR spectroscopy on the chiral statTonary phase (CSP) derTved from (18-crown-6)-2,3,11,12-tetracarbaxylic add (18-C-6-TA). The chromatographTc parameters such as separation factors and retention times were greatly influenced by the mobile phase conditions. The (+) 18 C 6IA used Tn the CSP was also employed as a chTral solvating agent for the enantTodiscrTmTnatTon of the D?A enantTomers by NMR spectroscopy. The proton of the DPA analyte showing the chemical shift nonequTvalenoes was used Tn determinTng the enantTomeric composTtion of the analyie.no alcohols and quinolone antibacterials. More recently, we reported detailed NMR studies on the chiral recognition mechanism of phenylglycine and phenylglycine methyl ester using (+)-18-C-6-TA as a chiral selector [9]. For the development of potent thrombin inhibitors, diphenylalanine (DPA), possessing a unique amino acid structure, has been used as an essential chiral precursor [10 12]. During the preparation of intermediates of these compounds, the determination of the enantiomeric purity of prepared DPA was needed. In this study we demonstrate the liquid chromatographic resolution of DPA using the 18-C-6-TA-derived CSP. We also show that the chiral selector, 18-C-6-TA used in the CSP, can be employed for resolution of DPA as a chiral solvating agent (CSA) by NMR spectroscopy [ 13,14].

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Eluting trace components before major constituents

Cited by 51 publications

References 5 publications

Separation of the enantiomers of pyrethroic acids and their esters by high-performance liquid chromatography on a polysaccharide-derived chiral stationary phase

Separation of the enantiomers of pyrethroic acids and their esters by high-performance liquid chromatography on a polysaccharide-derived chiral stationary phase

Macromolecular Helicity Induction and Memory in a Poly(biphenylylacetylene) Bearing an Ester Group and Its Application to a Chiral Stationary Phase for High-performance Liquid Chromatography

Chiral resolution of diphenylalanine by high-performance liquid chromatography on a crown-ether-based chiral stationary phase and by NMR spectroscopy

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