- Highly Stable Zr(IV)-Based Metal-Organic Frameworks for Chiral Separation in Reversed-Phase Liquid Chromatography
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Separation of racemic mixtures is of great importance and interest in chemistry and pharmacology. Porous materials including metal-organic frameworks (MOFs) have been widely explored as chiral stationary phases (CSPs) in chiral resolution. However, it remains a challenge to develop new CSPs for reversed-phase high-performance liquid chromatography (RP-HPLC), which is the most popular chromatographic mode and accounts for over 90% of all separations. Here we demonstrated for the first time that highly stable Zr-based MOFs can be efficient CSPs for RP-HPLC. By elaborately designing and synthesizing three tetracarboxylate ligands of enantiopure 1,1′-biphenyl-20-crown-6, we prepared three chiral porous Zr(IV)-MOFs with the framework formula [Zr6O4(OH)8(H2O)4(L)2]. They share the same flu topological structure but channels of different sizes and display excellent tolerance to water, acid, and base. Chiral crown ether moieties are periodically aligned within the framework channels, allowing for stereoselective recognition of guest molecules via supramolecular interactions. Under acidic aqueous eluent conditions, the Zr-MOF-packed HPLC columns provide high resolution, selectivity, and durability for the separation of a variety of model racemates, including unprotected and protected amino acids and N-containing drugs, which are comparable to or even superior to several commercial chiral columns for HPLC separation. DFT calculations suggest that the Zr-MOF provides a confined microenvironment for chiral crown ethers that dictates the separation selectivity.
- Jiang, Hong,Yang, Kuiwei,Zhao, Xiangxiang,Zhang, Wenqiang,Liu, Yan,Jiang, Jianwen,Cui, Yong
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supporting information
p. 390 - 398
(2021/01/13)
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- Evaluation of the Edman degradation product of vancomycin bonded to core-shell particles as a new HPLC chiral stationary phase
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A modified macrocyclic glycopeptide-based chiral stationary phase (CSP), prepared via Edman degradation of vancomycin, was evaluated as a chiral selector for the first time. Its applicability was compared with other macrocyclic glycopeptide-based CSPs: TeicoShell and VancoShell. In addition, another modified macrocyclic glycopeptide-based CSP, NicoShell, was further examined. Initial evaluation was focused on the complementary behavior with these glycopeptides. A screening procedure was used based on previous work for the enantiomeric separation of 50 chiral compounds including amino acids, pesticides, stimulants, and a variety of pharmaceuticals. Fast and efficient chiral separations resulted by using superficially porous (core-shell) particle supports. Overall, the vancomycin Edman degradation product (EDP) resembled TeicoShell with high enantioselectivity for acidic compounds in the polar ionic mode. The simultaneous enantiomeric separation of 5 racemic profens using liquid chromatography-mass spectrometry with EDP was performed in approximately 3?minutes. Other highlights include simultaneous liquid chromatography separations of rac-amphetamine and rac-methamphetamine with VancoShell, rac-pseudoephedrine and rac-ephedrine with NicoShell, and rac-dichlorprop and rac-haloxyfop with TeicoShell.
- Hellinghausen, Garrett,Lopez, Diego A.,Lee, Jauh T.,Wang, Yadi,Weatherly, Choyce A.,Portillo, Abiud E.,Berthod, Alain,Armstrong, Daniel W.
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p. 1067 - 1078
(2018/08/01)
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- The preparation method of the levodopa intermediate derivatives
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The invention relates to a preparation method for a levodopa intermediate derivative. The preparation method comprises: in a solvent, reacting 3, 4-dimethoxybenzene phenylalanine shown as formula I with (+)-tartaric acid derivative to obtain the salt of a [(-)-3, 4-dimethoxybenzene phenylalanine]2.(+)- tartaric acid derivative. The solvent includes an alcohol solvent and an ester solvent. The racemization method includes: in the solvent, under the action of an aldehyde or ketone catalyst, reacting the 3, 4-dimethoxybenzene phenylalanine shown as formula I at 0-90DEG C for 0.5-24 h. The preparation method for the levodopa intermediate derivative provided by the invention has simple steps, and the prepared enantiomer has high purity and is low in cost, thus being applicable to industrial production. (reaction formula).
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- Chiral ligand-exchange resolution of underivatized amino acids on a dynamically modified stationary phase for RP-HPTLC
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The synthesis of Spi(τ-dec), derived from the selective alkylation of L-spinacine (4,5,6,7-tetrahydro-1H-imidazo[4,5-c]pyridine-6-carboxylic acid) at the τ-nitrogen of its heteroaromatic ring, with a linear hydrocarbon chain of 10 carbon atoms, is described here for the first time. Spi(τ-dec) was successfully employed in the past to prepare home-made chiral columns for chiral ligand-exchange high-performance liquid chromatography. In the present article a new method is described, using Spi(τ-dec) as a chiral selector in high-performance thin-layer chromatography (HPTLC): commercial hydrophobic plates were first coated with Spi(τ-dec) and then treated with copper sulfate. The performance of this new chiral stationary phase was tested against racemic mixtures of aromatic amino acids, after appropriate optimization of both the conditions of preparation of the plates and the mobile phase composition. The enantioselectivity values obtained for the studied compounds were higher than those reported in the literature for similar systems. The method employed here for the preparation of chiral HPTLC plates proved practical, efficient, and inexpensive. Chirality 26:313-318, 2014. 2014 Wiley Periodicals, Inc.
- Remelli, Maurizio,Faccini, Stefania,Conato, Chiara
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p. 313 - 318
(2014/06/09)
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- SEPARATING AGENT FOR CHROMATOGRAPHY
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A separating agent for chromatography is provided that is useful for the separation of specific compounds, e.g., for the optical resolution of amino acids. This separating agent for chromatography provides a higher productivity and contains a crown ether-like cyclic structure and optically active binaphthyl. This separating agent for chromatography containing a crown ether-like cyclic structure and optically active binaphthyl is provided by introducing a substitution group for binding to carrier into a specific commercially available 1,1′-binaphthyl derivative that has substituents at the 2, 2′, 3, and 3′ positions, then introducing a crown ether-like cyclic structure, and subsequently chemically bonding the binaphthyl derivative to the carrier through the substitution group for binding to carrier.
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Paragraph 0074; 0075
(2013/08/15)
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- COMPOSITIONS AND METHODS FOR CYCLOFRUCTANS AS SEPARATION AGENTS
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The present invention relates to derivatized cyclofructan compounds, compositions comprising derivatized cyclofructan compounds, and methods of using compositions comprising derivatized cyclofructan compounds for chromatographic separations of chemical species, including enantiomers. Said compositions may comprise a solid support and/or polymers comprising derivatized cyclofructan compounds.
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Page/Page column 45-49; 61
(2010/12/31)
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- Stereospecificity of mushroom tyrosinase immobilized on a chiral and a nonchiral support
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Mushroom tyrosinase was immobilized from an extract onto glass beads covered with the cross-linked totally cinnamoylated derivates of D-sorbitol (sorbitol cinnamate) and glycerine (glycerine cinnamate). The enzyme was immobilized onto the support by direct adsorption, and the quantity of immobilized tyrosinase was higher for sorbitol cinnamate, the support with the higher number of esterified hydroxyls per unit of monosacharide, than for glycerine cinnamate. The results obtained from the stereospecificity study of the monophenolase and diphenolase activity of immobilized mushroom tyrosinase are reported. The enantiomers L-tyrosine, DL-tyrosine, D-tyrosine, L-dopa, DL-dopa, D-dopa, L-α-methyldopa, DL-α-methyldopa, L-isoprenaline, DL-isoprenaline, L-adrenaline, DL-adrenaline, L-noradrenaline, and D-noradrenaline were assayed with tyrosinase immobilized on a chiral support (sorbitol cinnamate), whereas L-tyrosine, DL-tyrosine, D-tyrosine, L-dopa, DL-dopa, D-dopa, L-α-methyldopa, and DL-α-methyldopa were assayed with tyrosinase immobilized on a nonchiral support (glycerine cinnamate). The same Vmaxapp values for each series of enantiomers were obtained. However, the Kmapp values were different, the L isomers showing lower values than the DL isomers, whereas the highest K mapp value was obtained with D isomers. No difference was observed in the stereospecificity of tyrosinase immobilized on a chiral (sorbitol cinnamate) or nonchiral (glycerine cinnamate) support.
- Marin-Zamora, Maria Elisa,Rojas-Melgarejo, Francisco,Garcia-Canovas, Francisco,Garcia-Ruiz, Pedro Antonio
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p. 4569 - 4575
(2008/02/09)
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- Cavity effects on the enantioselectivity of chiral amido[4]resorcinarene stereoisomers
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The dramatic effects of the size and hydrophilic/hydrophobic properties of cavities on the intrinsic reaction kinetics and dynamics is shown by the gas-phase reaction of (R)-(-)-2-butylamine and complexes of stereoisomeric amido[4]resorcinarene hosts with aromatic amino acids. The graph shows the kinetic plots of the base-induced loss of L-Phe (green), L-Tyr (red), and L-dopa (blue).
- Botta, Bruno,Subissati, Deborah,Tafi, Andrea,Delle Monache, Giuliano,Filippi, Antonello,Speranza, Maurizio
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p. 4767 - 4770
(2007/10/03)
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- Retention and selectivity of teicoplanin stationary phases after copper complexation and isotopic exchange
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Teicoplanin is a macrocyclic glycopeptide that is highly effective as a chiral selector for LC enantiomeric separations. Two possible interaction paths were investigated and related to solute retention and selectivity: (1) interactions with the only teicoplanin amine group and (2) role of hydrogen bonding interactions. Mobile phases containing 0.5 and 5 mM copper ions were used to try to block the amine group. In the presence of copper ions, it was found that the teicoplanin stationary phase has a decreased ability to separate most underivatized racemic amino acids. However, it maintained its ability to separate enantiomers that were not α - amino acids. It is established that there is little copper - teicoplanin complex formation. The effect of Cu2+ on the enantioseparation of some α - amino acids appears to be due to the fact that these solutes are good bidentate ligands and form complexes with copper ions in the mobile phase. Isotopic exchange with deuterium oxide was performed using acetonitrile - heavy water mobile phases. It was found that the retention times of all amino acids were lower with deuterated mobile phases. The retention times of polar or apolar molecules without amine groups were higher with deuterated mobiles phases. In all cases, the enantio-selectivity factors were unaffected by the deuterium exchange. It is proposed that the electrostatic interactions are decreased in the deuterated mobile phases and the solute-accessible stationary-phase volume is somewhat swollen by deuterium oxide. The balance of these effects is a decrease in the amino acid retention times and an increase in the apolar solute retention time. The enantio-selectivity factors of all of the molecules remain unchanged because all of the interactions are changed equally. We propose a new global quality criterion (the E factor) for comparing and evaluating enantiomeric separations.
- Berthod,Valleix,Tizon,Leonce,Caussignac,Armstrong
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p. 5499 - 5508
(2007/10/03)
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- Chemo-enzymatic synthesis of optically active amino acids and peptides
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The industrial alkaline protease, alcalase, is stable and active in a high concentration of organic solvents and useful as a biocatalyst for (i) diastereoselective hydrolysis of peptide esters and preparation of racemization-free peptides; (ii) selective incorporation of esters of D-amino acid into peptides in t-butanol via a selective hydrolysis of esters of D,L-amino acid, followed by using the unhydrolyzed D-esters as a nucleophile in a kinetically controlled peptide bond formation; (iii) resolution of esters of amino acid in 95% t-butanol/5% water, followed by saponification of the unreacted esters to offer both enantiomers with high yield and optical purity; (iv) completely resolve amino-acid esters with high yield and optical purity via in situ racemization of the unreacted antipode catalyzed by pyridoxal 5-phosphate; (v) cryobioorganic synthesis of peptides with increased yields 15%-40% of peptide bond formation by reaction at 5 °C instead of 25-30 °C of a kinetically controlled enzymatic reaction in alcohols.
- Chen, Shui-Tein,Wang, Kung-Tsung
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p. 301 - 311
(2007/10/03)
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- Mechanism of Asymmetric Production of D-Amino Acids from the Corresponding Hydantoins by Pseudomonas sp.
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The mechanism of asymmetric production of D-amino acids from the corresponding hydantoins by Pseudomonas sp.AJ-11220 was examined by investigating the properties of the enzymes involved in the hydrolysis of DL-5-substituted hydantoins.The enzymatic production of D-amino acids from the corresponding hydantoins by Pseudomonas sp.AJ-11220 involved the following two successive reactions; the D-isomer specific hydrolysis, i.e., the ring opening of D-5-substituted hydantoins to D-form N-carbamyl amino acids by an enzyme, D-hydantoin hydrolase (D-HYD hydrolase), followed by the D-isomer specific hydrolysis, i.e., the cleavage of N-carbamyl-D-amino acids to D-amino acids by an enzyme, N-carbamyl-D-amino acid hydrolase (D-NCA hydrolase).L-5-Substituted hydantoins not hydrolyzed by D-HYD hydrolase were converted to D-form 5-substituted hydantoins through spontaneous racemization under the enzymatic reaction conditions.It was proposed that almost all of the DL-5-substituted hydantoins were stoichiometrically and directly converted to the corresponding D-amino acids through the successive reactions of D-HYD hydrolase and D-NCA hydrolase in parallel with the spontaneous racemization of L-5-substituted hydantoins to those of DL-form.
- Yokozeki, Kenzo,Kubota, Koji
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p. 721 - 728
(2007/10/02)
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- alpha -AMINO ACIDS AS CHIRAL EDUCTS FOR ASYMMETRIC PRODUCTS. A GENERAL SYNTHESIS OF D- alpha -AMINO ACIDS FROM L-SERINE.
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A short and chirally efficient synthesis of four D- alpha -amino acids is described with L-serine as the chiral educt. The key C-C bond-forming reactions are the aminoacylations of organometallics with the lithium salt of N-(phenylsulfonyl)-L-serine (2) to give optically pure N-blocked alpha -amino ketones. Reduction of the carbonyl group to carbinol or methylene followed by oxidation of the hydroxymethyl to carboxyl gives the N-blocked D-amino acids. The examples investigated (norleucine, alpha -aminopimelic acid, DOPA, and allothreonine) demonstrate the broad applicability of the method.
- Maurer,Takahata,Rapoport
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p. 1095 - 1098
(2007/10/02)
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