The enantiomeric separation of 4,5-disubstituted imidazoles by HPLC and CE using cyclodextrin-based chiral selectors

Breitbach, Zachary S.; Feng, Qing; Koswatta, Panduka B.; Dodbiba, Edra; Lovely, Carl J.; Armstrong, Daniel W.

doi:10.1080/10610278.2010.506545

Cited by 13 publications

(13 citation statements)

References 26 publications

(25 reference statements)

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“…All the compounds studied by HPLC were also investigated by CE using derivatized cyclodextrins as chiral selectors. In a related study, sulfated‐β‐CD was reported as an optimum chiral selector for similar compounds . However, when using sulfated‐β‐CD in this study, no enantiomeric separations was observed in either normal or reverse polarity modes.…”

Section: Resultsmentioning

confidence: 52%

“…In a related study, sulfated-b-CD was reported as an optimum chiral selector for similar compounds. 39 However, when using sulfated-b-CD in this study, no enantiomeric separations was observed in either normal or reverse polarity modes. Clearly, this set of alkaloid compounds behave much differently than those studied previously.…”

Section: Ce Analysesmentioning

confidence: 52%

“…However, when using sulfated‐β‐CD in this study, no enantiomeric separations was observed in either normal or reverse polarity modes. Clearly, this set of alkaloid compounds behave much differently than those studied previously …”

Section: Resultsmentioning

confidence: 70%

“…Typically, cyclodextrin-based CSPs in the reversed phase mode form a strong inclusion complex between the hydrophobic portions of the analytes and the cyclodextrin cavity. 1,21,39,40 During this work, optimal aqueous/organic ratios were varied from 50/50 to 85/15. Compound C was the only analyte that had an optimized separation using the polar organic mode (Table 1).…”

Section: Results and Discussion Hplc Analysesmentioning

confidence: 99%

“…Clearly, this set of alkaloid compounds behave much differently than those studied previously. 39 Alternatively, neutral chiral selectors were considered for separating the tetrahydrobenzimidazoles. As is typical of capillary zone electrophoresis (CZE) separations, alterations in pH were extremely important in achieving enantiomeric separations.…”

Section: Ce Analysesmentioning

confidence: 99%

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The Enantiomeric Separation of Tetrahydrobenzimidazoles Cyclodextrins‐ and Cyclofructans

Perera

Doundoulakis

et al. 2012

Chirality

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High performance liquid chromatography (HPLC) and capillary electrophoresis (CE) were used to examine the enantiomeric separation of a series of 17 racemic tetrahydrobenzimidazole analytes. These compounds were prepared as part of a synthetic program directed towards a select group of pyrrole-imidazole alkaloids. This group of natural products has a unique framework of pyrrole- and guanidine-containing fused rings which can be constructed through the intermediacy of a tetrahydrobenzimidazole scaffold. Several bonded cyclodextrin- (both native and derivatized) and derivatized cyclofructan-based chiral stationary phases were evaluated for their ability to separate these racemates via HPLC. Similarly, several cyclodextrin derivatives and derivatized cyclofructan were evaluated for their ability to separate this set of chiral compounds via CE. Enantiomeric selectivity was observed for the entire set of racemic compounds using HPLC with resolution values up to 3.0. Among the 12 different CSPs, enantiomeric recognition was most frequently observed with the Cyclobond RN and LARIHC CF6-P, while the Cyclobond DMP yielded the greatest number of baseline separations. Fifteen of the analytes showed enantiomeric recognition in CE with resolution values as high as 5.0 and hydroxypropyl-γ-cyclodextrin was the most effective chiral additive.

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Section: Resultsmentioning

confidence: 52%

Section: Ce Analysesmentioning

confidence: 52%

Section: Resultsmentioning

confidence: 70%

Section: Results and Discussion Hplc Analysesmentioning

confidence: 99%

Section: Ce Analysesmentioning

confidence: 99%

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The Enantiomeric Separation of Tetrahydrobenzimidazoles Cyclodextrins‐ and Cyclofructans

Perera

Doundoulakis

et al. 2012

Chirality

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Chiral Separations by High‐Performance Liquid ChromatographyUpdate based on the original article by Timothy J. Ward and Tanya M. Oswald,Encyclopedia of Analytical Chemistry, © 2000, John Wiley & Sons, Ltd.

Ward

2012

Encyclopedia of Analytical Chemistry

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The word ‘chiral’ is derived from the Greek word ‘cheir’, which means hand. Chiral molecules are molecules that are related to each other in the same way that a left hand is related to a right hand. These molecules are mirror images of each other and are nonsuperimposable. Chiral separations traditionally have been considered among the most difficult of all separations because enantiomers have identical chemical and physical properties in an achiral environment. In this article, we focus on techniques used in high‐performance liquid chromatography (HPLC). Most chiral separations by HPLC are accomplished via direct resolution using a chiral stationary phase (CSP). In this technique, a chiral resolving agent is bound or immobilized to an appropriate support to make a CSP, and the enantiomers are resolved by the formation of temporary diastereomeric complexes between the analyte and the CSP. Various types of CSPs have been developed, including polysaccharide‐based, cyclodextrin‐based, cyclofructan‐based, macrocyclic antibiotic‐based, protein‐based, Pirkle‐type, and ligand‐exchange CSPs. The most commercially common CSPs, polysaccharide‐based phases, consist of derivatized cellulose and amylose coated on silica gel and a new generation of polysaccharide‐based phases, which is immobilized through covalent bonding to a silica gel. Generally, analytes separated using the cyclodextrins require the formation of an inclusion complex between the analyte and the cyclodextrin. Separation is most favorable when the analyte also interacts with the mouth of the cyclodextrin molecule via hydrogen bonding to the functional groups present. The cyclofructan‐based CSPs are the newest development in chiral HPLC columns and are now available commercially. These bonded CSPs show excellent enantioselectivity toward all types of primary amines as well as other varieties of compounds. Numerous analytes have been separated using the macrocyclic antibiotic‐based CSPs, which can also be derivatized to alter their selectivity. Protein‐based CSPs comprise a number of commercially available columns. The protein‐based CSPs resemble the bonded macrocyclic antibiotic CSPs in many ways; however, the macrocyclic antibiotic CSPs are more stable and have greater capacities than the protein‐based CSPs. The Pirkle‐type CSPs typically use nonpolar organic mobile phases and often require derivatization of the analyte to add a π‐acid or π‐basic moiety, or both, to achieve separation. Ligand‐exchange phases are used with aqueous buffer mobile phases in which enantiomers are separated based on the differences in their charge and ionization constants. Limitations of ligand‐exchange separations are that only ionized analytes can be resolved using this technique and the copper‐salt‐containing mobile phases used absorb in the ultraviolet (UV) region, decreasing detection sensitivity.

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Chiral Separations by High‐Performance Liquid Chromatography

Ward

Bravenec

Ward

2019

Encyclopedia of Analytical Chemistry

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The enantiomeric separation of 4,5-disubstituted imidazoles by HPLC and CE using cyclodextrin-based chiral selectors

Cited by 13 publications

References 26 publications

The Enantiomeric Separation of Tetrahydrobenzimidazoles Cyclodextrins‐ and Cyclofructans

The Enantiomeric Separation of Tetrahydrobenzimidazoles Cyclodextrins‐ and Cyclofructans

Chiral Separations by High‐Performance Liquid ChromatographyUpdate based on the original article by Timothy J. Ward and Tanya M. Oswald,Encyclopedia of Analytical Chemistry, © 2000, John Wiley & Sons, Ltd.

Chiral Separations by High‐Performance Liquid Chromatography

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