Impact of amines as co-modifiers on the enantioseparation of various amino acid derivatives on a tert-butyl carbamoylated quinine-based chiral stationary phase

A tert-butyl carbamoylated quinine-based chiral stationary phase (CSP) for direct enantiomer separation of various natural and unnatural amino acid derivatives was studied. The influence of functional groups in the amino acid side chains upon the enantioseparation is discussed with the aim of realizing contributions to their overall chiral recognition. The effects of various amines as co-modifiers upon retention and overall enantioselectivity of amino acid derivatives in polar organic solvents was systematically investigated. In general, retention times decreased with increasing amine concentrations without a distinct alteration of enantioselectivity. All analytes were rapidly resolved on the CSP with the methanol-based mobile phase containing 87 mM acetic acid and 7 mM triethylamine.     

键合偶联双奎宁手性固定相的制备和手性拆分性能

键合偶联双奎宁手性固定相的制备和手性拆分性能;手性固定相;奎宁;高效液相色谱;拆分     

Quaternary salts of alkaloids

New biologically active quaternary salts of the alkaloids ajmaline, quinine, hyoscyamine, codeine, and strychnine were synthesized. So-called separable conformers were observed among the ajmaline derivatives. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 381–383, July–August, 2006.     

Direct High‐Performance Liquid Chromatographic Enantioseparation of β‐Methyl‐Substituted Unusual Amino Acids on a Quinine‐Derived Chiral Anion‐Exchange Stationary Phase

A quinine‐derived chiral anion‐exchange stationary phase was used for the direct high‐performance liquid chromatographic separation of the enantiomers of the N‐protected unusual β‐substituted α‐amino acids, β‐methylphenylalanine, β‐methyltyrosine, β‐methyltryptophan, and β‐methyl‐1,2,3,4‐tetrahydroisoquinoline‐3‐carboxylic acid. The readily prepared 2,4‐dinitrophenyl and tert‐butyloxycarbonyl derivatives were well separated, and in most cases the separation of all four stereoisomers of these β‐methyl‐α‐amino acids could be obtained in one chromatographic run. The elution sequences of the enantiomers of the different derivatives were determined and revealed a dependence on the type of the N‐protecting group. In this context, the effects of different protecting groups (acetyl, tert‐butyloxycarbonyl, benzoyl, 3,5‐dinitrobenzoyl, benzyloxycarbonyl, 3,5‐dinitrobenzyloxycarbonyl, 2,4‐dinitrophenyl, and 9‐fluorenylmethoxycarbonyl) on the chromatographic behavior were investigated.     

ICP-AES研究负载奎宁树脂对金、铂、钯的吸附

利用奎宁能与贵金属的络阴离子发生络合作用的性质,将其负载到阳离子交换树脂上,制得奎宁负载树脂（ Ｑ Ｃ Ｒ） ．以 Ｉ Ｃ Ｐ Ａ Ｅ Ｓ为检测手段,详细考察了吸附材料在静态吸附条件下对贵金属络阴离子的富集分离性能．结果表明, 在盐酸（０．１～３．０ ｍ ｏｌ／ Ｌ） 溶液中,负载奎宁树脂的化学稳定性好．以０．１ ｍ ｏｌ／ Ｌ的 Ｈ Ｃｌ为吸附介质,贵金属 Ａｕ、 Ｐｄ、 Ｐｔ可实现定量分离富集,吸附于奎宁树脂上的贵金属可用０．１ ｍ ｏｌ／ Ｌ 的 Ｈ Ｃｌ－ ２ ｇ／ Ｌ 硫脲混合淋洗液完全解脱．方法用于抗癌药物及催化剂中 Ｐｔ、 Ｐｄ 的富集分离与测定,分析结果满意     

Conformational analysis of the antimalarial agent quinine

Quinine, an active antimalarial compound, is one of the most abundant constituents extracted from the bark ofCinchona trees. The activity differences among structurally related molecules appear to depend on the absolute stereochemistry of some functional groups, a result that has stimulated a detailed conformational analysis of these molecules of biological interest. In the present study the potential energy surface (PES) for the antimalarial agent quinine (C₂₀H₂₄O₂N₂) has been comprehensively investigated using the molecular mechanics (MM) and quantum mechanical semiem-pirical AM1 and PM3 methods. Six distinct minimum-energy structures are located on the multidimensional PES and also characterized as true minima through harmonic frequency analysis. The relative stabilities and thermodynamic properties are reported. The coexistence of different conformers is discussed for the first time in the literature based on the calculated transition-state (TS) structures connecting the six minima located on the PES for the quinine molecule. The theoretical results reported in the present study are in agreement with the experimental proposal, based on NMR data, that there are two possible forms for the quinine molecule in solution.     

Keggin结构过渡金属杂多阴离子中配位水与奎宁的取代反应

The substitution reaction of quinine by the 18 types of heteropoly complexes, for these formed compounds are Keggin structure and the molecular formulas are [XM₁₁O₃₉M′(OH)₂]^6-(X=Si,Ge,P;M=Mo or W;M′=Co,Ni,Cu), was studied by the means of phase transfer. The results of characterization that were accomplished by UV and ESR indicated that the quinine does form the chemical bond with the hetropoly ligands. Spectral experiment demonstrated that the structure held the same when the heteropoly complex contained Cu²⁺ was reacted with qui-nine, while the heteropoly complex contained Ni²⁺ resulted in the changing of the structure. Such a result of op-tical rotatory opticity testified that quinine reacting with heteropoly acid contained transitional metals could form a kind of new complexes which were optical rotation.     

Synthesis and chiral micellization behavior of optically active amphiphilic diblock copolymer bearing quinine pendants

A novel optically active amphiphilic diblock copolymer bearing quinine pendants poly(ethylene oxide)‐b‐poly(glycidyl triazolyl‐L ‐quinine) (MPEO‐b‐PGTQ) was synthesized by “click” reaction of alkyne‐modified diblock copolymer poly(ethylene oxide)‐b‐poly(glycidyl propargyl ether) (MPEO‐b‐PGPE) and 9‐N₃‐quinine. The structure and composition of copolymers were characterized by gel permeation chromatography, ¹H nuclear magnetic resonance spectroscopy (¹H NMR), elemental analysis and optical rotation measurements, which showed that the synthetic route could provide the copolymer with well‐defined composition and with similar optical activity compared to its parent quinine. The micellization behavior of this chiral copolymer was investigated in different solvent systems. The results from fluorescence spectroscopy, UV spectroscopy, dynamic light scattering, transmission electron microscopy, ¹H NMR and circular dichroism (CD) spectroscopy indicated that the MPEO‐b‐PGTQ could form regular chiral spherical micelles in H₂O and Tetrahydrofuran‐H₂O (10:90, V/V) systems, and the state of aggregated chiral micelles depended on the nature of the medium. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3640–3650, 2009     

奎宁-冠醚组合型手性固定相直接拆分氨基酸的机理

合成了一种新型奎宁-冠醚组合型手性固定相(QN-CR CSP)并用于氨基酸手性对映体的直接拆分,该固定相对12种氨基酸对映体有良好的手性拆分能力。基于氨基酸手性识别中离子交换和络合的协同作用,建立了一种新型的等温吸附模型。通过迎头特殊点洗脱法(FACP)测定色氨酸(Trp)在不同金属离子添加剂条件下的等温吸附线,验证了模型的合理性。流动相中的Li⁺、Na⁺、K⁺等金属离子与氨基酸竞争固定相中的冠醚络合位点,随着金属离子与冠醚的络合作用力和络合吸附平衡常数增大,固定相对Trp的手性拆分能力下降。该模型的建立对理解氨基酸在此类固定相中的手性保留行为以及固定相结构的进一步优化具有重要意义。