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51.
Gengliang Yang Zhiwei Li Dexian Wang Zhefeng Zhang Erdong Liu Yi Chen 《Chromatographia》2002,56(7-8):515-518
Summary A high-performance liquid chromatographic method was developed for the chiral separation of a new anti-diabetic agent, N-(trans-4-isopropylcyclohexylcarbonyl)-D-phenylalanine,
and its L-enantiomer. The separation was performed on a Sumichiral OA-3300 column. Optimized mobile phase was 0.025 mol.L−1 ammonium acetate in methanol solution. UV detection was at 210 nm. Baseline chiral separation was obtained within 12 minutes.
The detection limits are 80 pg for the D-enantiomer and 120 pg for the L-enantiomer. RSD of the method was below 1% (n=5). 相似文献
52.
使用手性冠醚及手性柱的HPCE和HPLC法拆分伯胺类药物对映体的对比研究 总被引:3,自引:0,他引:3
报道了在缓冲液中添加 1 8-冠 - 6 -四甲酸 (1 8C6 H4 )的高效毛细管电泳法(HPCE)对 8个含氨基的药物进行拆分 ,低 p H值 (2 .0 6 )和较高浓度的 Tris缓冲液(2 0 mmol· L- 1)可加快手性分离。用手性柱 Crownpak CR(+)的高效液相色谱(HPLC)法对与前相同的 8个含氨基药物进行拆分 ,甲醇浓度增大 ,分离度 RS值有所减小。实验结果还表明 ,使用 HPCE法拆分的各物质 RS值大于使用 HPLC法拆分相应物质的 RS值。 相似文献
53.
The structure and phase behavior of liquid crystalline polymers (LCPs) having a common chiral side chain mesogen but different main chain structures have been investigated using small-angle X-ray scattering (SAXS). While the low molecular weight chiral side chain mesogen by itself exhibits ferroelectricity, the SAXS data of the side chain LCP with a flexible polyacrylate backbone contains a bilayered superstructure peak that is indicative of antiferroelectric order. The combined LCP with a nonpolar main chain mesogen also has a bilayered superstructure, but has a different structural organization in the proposed antiferroelectric phase compared to the side chain LCP. Further changes in the phase behavior and structural organization occur when a polar group is introduced into the main chain mesogen. A ferrielectric phase has been proposed to explain the observation of a trilayered superstructure in the corresponding SAXS data. The influence of the chemical structure and connectivity on the phase behavior and superstructure formation in the chiral LCPs is discussed. 相似文献
54.
Summary An HPLC reversed-phase ion interaction reagent method is presented, which makes use of chiral compounds as the interaction
reagents. By employing the optical isomeric forms of malic, tartaric and mandelic acids as the interaction reagents, a good
separation of D(−) and L(+) ascorbic acid has been achieved. The method has also been applied to the identification of vitamin
C in some medical formulations. The separation of te enantiomeric forms of DL malic acid has been attempted and a shor discussion
is presented about the elution sequence in chromatographic separation of D- and L-enantiomers. 相似文献
55.
1,4-双(9-O-奎宁)-2,3-二氮杂萘-OsO4催化烯烃的不对称氨羟化反应 总被引:1,自引:0,他引:1
在氧化-供氮试剂N-氯代氨基甲酸苄酯存在下,1,4-双(9-O-奎宁)-2,3-二氮杂萘-OsO4催化剂在5种烯烃的不对称氨羟化反应中表现出极高的对映选择性(85%~99%e.e.)和区域选择性,产率48%~68%. 相似文献
56.
Summary Enantiomeric separation of (–)-menthyl chloroformate derivatives of some chiral cardioactive drugs, on porous graphitic carbon (PGC), Hypercarb-S, is described. Capacity and separation factors of derivatives of the calcium channel blockers; amlodipine and UK52.829, the -blockers; atenolol, sotalol and propranolol, and mexiletine were studied in different chromatographic systems based on dichloromethane. A high content of a carboxylic acid in the mobile phase was found to decrease the retention and positively affect the stereoselectivity of the derivatives. A mobile phase with dichloromethane, acetonitrile and formic acid gave baseline separation of the enantiomers of amlodipine in less than 8 minutes. Results show that acetic acid and formic acid, may be regarded as strong organic solvents in PGC chromatography with nearly the same elution power as dichloromethane. 相似文献
57.
Summary Optically activeMichael adducts were synthesized by addition of 1,3-dicarbonyl compounds to conjugated nitroalkenes. Good chemical yields were obtained for nitroalkenes stabilized by an aromatic substituent without any further substituents at the double bond. Acetylacetone and methyl-2,3-dihydro-1-oxo-1H-indene-2-carboxylate were used asMichael donors and four cinchona alkaloids as chiral base catalysts. Enantiomeric excess determinations were performed by1H NMR spectroscopy in the presence of thePirkle alcohol and by HPLC on chiral stationary phases. A correlation between the relative configuration of the prevailing isomer of theMichael adduct and the catalysts was established.
Asymmetrische Katalyse, 103. Mitt.: EnantioselektiveMichael-Addition von 1,3-Dicarbonylverbindungen an konjugierte Nitroalkene
Zusammenfassung Optisch aktiveMichael-Addukte werden durch die Addition von 1,3-Dicarbonylverbindungen an konjugierte Nitroalkene synthetisiert. Gute chemische Ausbeuten werden für durch aromatische Substituenten stabilisierte Nitroalkene ohne weitere Substituenten an der Doppelbindung erreicht. Acetylaceton und 2,3-Dihydro-1-oxo-1H-inden-2-carbonsäuremethylester werden alsMichael-Donoren und vier Cinchona-Alkaloide als chirale basische Katalysatoren verwendet. Die Bestimmung des Enantiomerenüberschusses wird mittels1H-NMR-Spektroskopie in Gegenwart vonPirkle-Alkohol und HPLC an chiralen stationären Phasen durchgeführt. Eine Korrelation zwischen der relativen Konfiguration der Vorzugsisomeren derMichael-Addukte und den Katalysatoren wurde hergestellt.相似文献
58.
Summary The effect of perchlorate anion as mobile phase modifier on the separation factor, α, forN-(dansyl)-dl-norvaline andN-(dansyl)-dl-tryptophan on a human serum albumin (HSA) column was studied by varying the concentration,c, of the chaotropic agent and the column temperatureT. Gibbs-Helmholtz parameters Δ(ΔH) and Δ(ΔS) between thed andl enantiomers were determined from linear van't Hoff plots of lnα against 1/T. Thermodynamic results indicated that the enhancement of the separation factor observed asc was increased was enthalpically controlled owing to stereoselective H-bonding interactions. Such behavior was used to optimize
the chromatographic conditions for separation ofN-(dansyl)-amino acids on HSA. 相似文献
59.
Hao Li 《Tetrahedron letters》2007,48(12):2209-2211
2,2′-Disubstituted ferrocenecarboxaldehydes are subjected to zinc-mediated allylation to form homoallylic ferrocenyl alcohols. The effects of ortho-substituted functional groups on facial selectivities of planar chiral aldehydes were studied and it was found that the corresponding homoallylic alcohols were obtained as single diastereomers in excellent yields. 相似文献
60.
[2+2] Carbonylative cycloaddition of chiral imines to various allyl halides, under CO pressure, in the presence of Et3N, a catalytic amount of Pd(OAc)2 and PPh3 as ligand, are carried out. Separable diastereomeric mixtures of chiral alkenyl-β-lactams are isolated with good yields and high trans diastereoselections. Absolute configurations are assigned by X-ray measurements and 1H NMR spectroscopy. 相似文献