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91.
萘普生是一种消炎镇痛药 ,其 S对映体的抗炎作用是 R构型的 2 8倍 ,萘普生及其衍生物的拆分具有重要意义 .手性固定相 HPLC直接拆分 [1~ 4 ] 是最简便的分析方法 .氧化锆是近年来备受关注的色谱载体 [5,6 ] .Carr等 [7] 对碱性药物快速拆分表明氧化锆在手性分离Scheme1 Structuresof chiral naproxen and its derivatives中的独特选择性 .萘普生及其衍生物在锆基手性固定相上的分离未见文献报道 .本组利用自制的球形氧化锆制备了涂敷型纤维素 -三 ( 3,5 -二甲基苯基氨基甲酸酯 ) -Zr O2 手性固定相 ( CDMPC- Zr O2 - CSP) ,在正… 相似文献
92.
Yasushi OgawaMasahito Toyama Michinori KarikomiKazuo Haga Tadao Uyehara 《Tetrahedron letters》2003,44(10):2167-2170
Both enantiomers of (P)-(+)-2- and (M)-(−)-2-acetoxy-11,14-dimethyl[5]helicenes 8 were synthesized by asymmetric aromatic oxy-Cope rearrangement of the corresponding chiral bridged bicyclic compounds, which were obtained by enzymatic resolution. The absolute configurations of 8 were assigned by their circular dichroism spectra. 相似文献
93.
Roberto Dallocchio Barbara Sechi Alessandro Dessì Bezhan Chankvetadze Sergio Cossu Victor Mamane Robin Weiss Patrick Pale Paola Peluso 《Electrophoresis》2021,42(17-18):1853-1863
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. 相似文献
94.
Karen Wright Fernando FormaggioClaudio Toniolo Roland TörökAntal Péter Michel WakselmanJean-Paul Mazaleyrat 《Tetrahedron letters》2003,44(22):4183-4186
Resolution of trans 3-(9-fluorenylmethyloxycarbonylamino)-1-oxyl-2,2,5,5-tetramethylpyrrolidine-4-carboxylic acid (Fmoc-POAC-OH) was quickly achieved upon esterification with (aR)-1,1′-binaphthyl-2,2′-diol, chromatographic separation of the obtained diastereomers, and facile saponification of the aryl ester function with removal of the chiral auxiliary. 相似文献
95.
As the relation of chirality and activities of drugs is researched deeply, people become to re-alize the clinic importance of chirality. The different enantiomers of a drug can have vastly differ-ent pharmacological activities, pharmacokinetic processes and toxicity[1,2]. The most well-docu- mented example is that of the drug substance thalidomide. Bitter lessons and scientific research promote the interest in single-enantiomer drugs, so the potential of the chiral drug market is enormous[3]. … 相似文献
96.
The stereochemistry of reductive and non reductive Heck cyclisations of 4-substituted-1.4-dihydropyridines is reexamined. The both reactions occur mainly via an anti (from the C4 substituent) 5-exo process without any epimerisation of the C4-H. 相似文献
97.
Takashi Kitae Hiroshi Takashima Koji Kano 《Journal of inclusion phenomena and macrocyclic chemistry》1999,33(3):345-359
Chiral recognition of mandelic acid ( 1), acetylmandelic acid ( 2), 1-methoxyphenylacetic acid ( 3), phenylsuccinic acid ( 4), 2-phenylpropanoic acid ( 5) and ibuprofen ( 6) in their anionic forms by protonated 6A-amino-6A-deoxy--cyclodextrin (mono-NH3+--CD) and 6A,6D-diamino-6A,6D-dideo xy--cyclodextrin (di-NH3+--CD) has been studied by means of capillary zone electrophoresis (CZE) and 1H NMR spectroscopy. Both methods show the preferable guests for mono-NH3+--CD to be the (R)-enantiomers of 1, 3 and 5 and the (S)-enantiomers of 2, 4 and 6. Cooperative work of Coulomb interactions and inclusion is essential for chiral recognition of these anionic guests. 相似文献
98.
Hidetaka KogaEiji Wada 《Tetrahedron letters》2003,44(4):715-719
An efficient catalytic double asymmetric induction during the tandem transetherification-intramolecular hetero Diels-Alder reaction has been developed. The enantioselective tandem reaction of methyl (E)-4-methoxy-2-oxo-3-butenoate with rac-6-methyl-5-hepten-2-ol has been achieved to provide methyl (2R,4aS,8aR)-3,4,4a,8a-tetrahydro-2,5,5-trimethyl-2H,5H-pyrano[4,3-b]-pyran-7-carboxylate in good yield with effective kinetic resolution (up to 95% selectivity), high diastereoselectivity (up to 92% de), and high enantioselectivity (up to 97% ee) in the presence of (S,S)-tert-Bu-bis(oxazoline)-Cu(SbF6)2 and 5 Å molecular sieves. 相似文献
99.
Junfang GongEric Bonfand Eric BrownGilles Dujardin Véronique Michelet Jean-Pierre Genêt 《Tetrahedron letters》2003,44(10):2141-2144
The synthesis of chiral 1,2,3,5-substituted tetrahydropyrans has been realized via an asymmetric hetero Diels-Alder (HDA) reaction. The key step that involved a trisubstituted chiral enol ether derived from (R)-mandelic acid as the dienophile promoted the creation of three stereogenic centers with a remarkable and unprecedented endo and facial stereocontrol. The hydrogenation of the heteroadduct 2 was optimized by using Pd on charcoal and diisopropylethylamine, leading to a unique isomer. The chiral inductor was cleanly and stereoselectively removed via an acetal reduction, which demonstrated the potential of this methodology for the efficient construction of key intermediate of biologically active molecules. 相似文献
100.
Simultaneous enantioseparations of 15 racemic aromatic amino acids and L-mimosine for their chiral discrimination were achieved by neutral selector-modified capillary electrophoresis (CE) and by charged selector-modified CE. Among the diverse cyclodextrins (CDs) examined, hydroxypropyl (HP)-alpha-CD as the neutral selector and highly sulfated (HS)-gamma-CD as the charged selector provided best chiral environments of different enantioselectivities. Fairly good enantiomeric resolutions were achieved with the HP-alpha-CD mode except for racemic 6-hydroxy-3,4-dihydroxyphenylalanine, threo-3,4-dihydroxyphenylserine and homophenylalanine while high-resolution separations of all the enantiomeric pairs were achieved in the HS-gamma-CD mode except that L-mimosine was not detected and a partial resolution (0.6) for threo-3,4-dihydroxyphenylserine enantiomers. Relative migration times to that of internal standard under the respective optimum conditions were characteristic of each enantiomer with good precision (% RSD: 0.7-3.8), thereby enabling to cross-check the chemical identification of aromatic amino acids and also their chiralities. The method linearity was found to be adequate (r> 0.99) for the chiral assay of the aromatic amino acids investigated. When applied to extracts of three plant seeds, nonprotein amino acids such as L-mimosine (42 nug/g) from Mimosa pudica Linné, and L-3,4-dihydroxyphenylalanine (268 nug/g) from Vicia faba were positively detected along with L-tryptophan, L-phenylalanine and L-tyrosine. 相似文献