Study of chiral recognition mechanism of O,O-diethyl (p-methylbenzenesulfonamindo)-aryl(alkyl)-methylphosphonates by HPLC with a series of CSPs

Five chiral stationary phases (CSPs) were used to separate the enantiomers of a series of O,O-diethyl (p-methyl-benzenesulfonamindo)- aryl(alkyl)-methylphosphonates. A chiral recognition mechanism was presented to explain the resolution of these compounds. Results show that CSP with strong π-acceptor 3,5-dinitrobenzoyl group and high steric hindrance has the best resolution ability in chiral separation of O,O-diethyi (p-methyl-benzenesulfonamindo)- aryl(alkyl)-methylphosphonates. When a CSP has just a strong π-acceptor 3,5-dinitrobenzoyl or high steric hindrance it does not have good chiral resolution ability. The chiral recognition is more difficult when the CSP has more than one asymmetric center.     

Enantioseparations of polyhalogenated 4,4’-bipyridines on polysaccharide-based chiral stationary phases and molecular dynamics simulations of selector–selectand interactions

2’-(4-Pyridyl)- and 2’-(4-hydroxyphenyl)-TCIBPs (TCIBP = 3,3’,5,5’-tetrachloro-2-iodo-4,4’-bipyridyl) are chiral compounds that showed interesting inhibition activity against transthyretin fibrillation in vitro. We became interested in their enantioseparation since we noticed that the M-stereoisomer is more effective than the P-enantiomer. Based thereon, we recently reported the enantioseparation of 2’-substituted TCIBP derivatives with amylose-based chiral columns. Following this study, herein we describe the comparative enantioseparation of both 2’-(4-pyridyl)- and 2’-(4-hydroxyphenyl)-TCIBPs on four cellulose phenylcarbamate-based chiral columns aiming to explore the effect of the polymer backbone, as well as the nature and position of substituents on the side groups on the enantioseparability of these compounds. In the frame of this project, the impact of subtle variations of analyte and polysaccharide structures, and mobile phase (MP) polarity on retention and selectivity was evaluated. The effect of temperature on retention and selectivity was also considered, and overall thermodynamic parameters associated with the analyte adsorption onto the CSP surface were derived from van ’t Hoff plots. Interesting cases of enantiomer elution order (EEO) reversal were observed. In particular, the EEO was shown to be dependent on polysaccharide backbone, the elution sequence of the two analytes being P-M and M-P on cellulose and amylose tris(3,5-dimethylphenylcarbamate), respectively. In this regard, a theoretical investigation based on molecular dynamics (MD) simulations was performed by using amylose and cellulose tris(3,5-dimethylphenylcarbamate) nonamers as virtual models of the polysaccharide-based selectors. This exploration at the molecular level shed light on the origin of the enantiodiscrimination processes.     

Preparation and characterization of phenyl carbamate derivative β-cyclodextrin bonded phase for chiral HPLC

A partially substituted β-cyclodextrin chiral stationary phase was prepared by the reaction of phenyl isocyanate. The enantiomers of a series of O,O-diethyl(p-methylbenzenesulfonamido)-aryl(or alkyl)-methylphosphonates were studied on the prepared phenyl carbamate derivative β-cyclodextrin bonded phase and a commercial (S)-(+)-1–(1-naphthyl) ethylcarbamate derivative β-cyclodextrin bonded phase on normal phase chromatographic condition. Results show that the prepared phenyl carbamate derivative β-cyclodextrin bonded phase has better enantiomeric selectivity to the series of compounds. A chiral recognition mechanism was suggested for the separation of these novel organic phosphorus enantiomers.     

QSERRs方法及其在色谱手性识别机理研究中的应用

介绍了定量结构-对映保留关系(QSERRs)方法及其在色谱手性识别机理研究中的应用。引用文献31篇。     

键合型纤维素3，5-二甲基苯基氨基甲酸酯手性固定相的制备及分离性能研究

将溶于N,N-二甲基乙酰胺-LiCl-吡啶的纤维素混合液直接涂敷于氨丙基硅胶上,分别以4,4′-二苯基甲烷二异氰酸酯和1,6-己二异氰酸酯为间隔臂将纤维素键合到硅胶上,并通过与过量的3,5-二甲基苯基异氰酸酯反应,制得2种键合型纤维素3,5-二甲基苯基氨基甲酸酯手性固定相。考察了固定相的分离性能。研究表明,所制备的手性固定相具有较高的手性识别能力和溶剂耐受性,相比于常规流动相（正己烷/异丙醇混合液）,当流动相中含有三氯甲烷或四氢呋喃时,多数对映体得到了更好的分离,且二异氰酸酯的种类对手性固定相的手性识别能力影响较小。     

Enantiomeric Recognition of d- and l-Amino Acid Methyl Ester Hydrochlorides by New Chiral Bis-pyridino-18-crown-6 Substituted with Urea, and Diphenyl Groups

The article reports the synthesis and chiral recognition properties of a new chiral bis-pyridino-18-crown-6 (7), having urea, diphenyl, and allyloxy groups. The chiral bis-pyridino-18-crown-6 was prepared by a thirteen-steps procedure from the commercially available (S)-(+)-mandelic acid and chelidamic acid. The association constants (K _a) (1.33 × 10³–3.20 × 10³) for enantiomeric recognition of d- and l-amino acid methyl ester hydrochlorides using the chiral bis-pyridino-18-crown-6 have been examined by ¹H-NMR titration method in CDCl₃ at 25 °C. The chiral bis-pyridino-18-crown-6 showed higher association constants for the d-series amino acid methyl ester (d-AlaOMe, d-LeuOMe, d-MetOMe) hydrochlorides as compared to the corresponding l-series (l-AlaOMe, l-LeuOMe, l-MetOMe) hydrochlorides.     

大环化合物色谱固定相分离机理研究的新进展

简要介绍了近年来被用于大环化合物色谱固定相保留机理研究的一些新的方法和理论,重点对几种典型大环超分子主体化合物作为色谱固定相对其分离机理研究的近况进行了综述。     

Enantiomer elution order reversal of fluorenylmethoxycarbonyl-isoleucine in high-performance liquid chromatography by changing the mobile phase temperature and composition

In this paper the elution order reversal of enantiomers of fluorenylmethoxycarbonyl- or FMOC-isoleucine is described depending on the separation temperature and composition of the mobile phase when using the polysaccharide-based chiral column Lux Cellulose-1 in HPLC with normal-phase eluent. Reversal of the enantiomer elution order (EEO) in HPLC depending on the column temperature and content of the polar modifier in the mobile phase has been reported before in the literature. However, EEO reversal by changing the content of acidic modifier in the mobile phase seems to be described for the first time in the present work.     

Chiral stationary phases based on cinchona alkaloids for the HPLC resolution of racemates

Summary The employment of three chiral stationary phases (CSPs) obtained by derivatizing γ-mercaptopropyl-silanized silica gel with quinine, quinidine and N-methyl-quinium iodide, for the separation of organic racemates, is presented. They are quite useful in the resolution of alkylarylcarbinols, binaphthyl derivatives, amides and other substances of pharmaceutical interest.     

双手性选择单元手性固定相的研究进展

手性固定相（chiral stationary phase,CSP）作为手性色谱分离的核心技术,在手性化合物的识别和分离中得到广泛应用。以双手性选择单元结合作为CSP是近些年的研究热点,研究表明,两种手性选择单元相结合的CSP可增加手性识别位点,显著提高分离效果。本文介绍了近几年双手性选择单元手性固定相在手性分离中的研究进展,并对其发展前景进行了展望。