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1.
《结构化学》2003,(1)
Aschemicalnomenclaturewasoriginallydevelopedforcompoundsinthesolutionstate,thereissomeconfusionintheproperuseoftheterm慶hiralfordescribingcertaincrystalstructures.Thishasledtoanumberofcompoundsbeingincorrectlycategorizedasbeingchiralalthoughtheybelongtocentrosymmetricspacegroupsorthosehavingmirrorplanes.Achiralcompoundthatseparatesfromsolutionasacrystallinematerialmustnecessarilypackinamotifsuchthatothermoleculesintheunitcellarenotsuperimposableontheirownmirrorimages.Theconditionforopticalacti… 相似文献
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Erythromycin as a new chiral selector was first used for chrial separation of four derivatives of biphenyldimethylester enantiomers on CE.The influence of pH,the chiral selector concentration and organic modifiers were preliminarily studied.Experiments show that the erythromycin as chiral selector is useful to CE. 相似文献
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The reactions of chiral four-coordinated nickel(Ⅱ) complex [Ni(RR-L)](ClO4)2/[Ni(SS- L)](ClO4)2 with β-dl-phenylalanine in acetonitrile/water gave a six-coordinated enantiomer of [Ni(RR-L)(β-d-HPhe)](ClO4)2(1) and [Ni(SS-L)(β-l-HPhe)](ClO4)2(2), respectively(L = 5,5,7, 12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane, HPhe = phenylalanine). Single-crystal X-ray diffraction analyses revealed that the nickel(Ⅱ) atom displays a distorted octahedral coordination geometry by coordinating with four nitrogen atoms of L in a folded configuration, and two carboxylate oxygen atoms of β-d/l-HPhe in cis-position in both complexes. The monomers of [Ni(RR-L)(β-d-HPhe)]2+ and [Ni(SS-L)(β-l-HPhe)]2+ are connected through intermolecular hydrogen bonds to generate one-dimensional zigzag chains, respectively. The homochiral natures of 1 and 2 are confirmed by the results of CD spectroscopy. 相似文献
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Xian Xian LIU Yan Song ZHENG Wan Ling MO 《中国化学快报》2006,17(9):1169-1172
Parent calixarenes are inherently highly symmetrical and are, therefore, achiral molecules. Hence, two strategies have been developed to prepare chiral calixarenes. The first method involves the construction of the asymmetric calixarene frame by introduci… 相似文献
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Zexi Liu Jing Ai Dr. Prashant Kumar Enming You Dr. Xiong Zhou Dr. Xi Liu Prof. Zhongqun Tian Prof. Petr Bouř Dr. Yingying Duan Prof. Lu Han Prof. Nicholas A. Kotov Prof. Songyuan Ding Prof. Shunai Che 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(35):15338-15343
A surface-enhanced Raman scattering-chiral anisotropy (SERS-ChA) effect is reported that combines chiral discrimination and surface Raman scattering enhancement on chiral nanostructured Au films (CNAFs) equipped in the normal Raman scattering Spectrometer. The CNAFs provided remarkably higher enhancement factors of Raman scattering (EFs) for particular enantiomers, and the SERS intensity was proportional to the enantiomeric excesses (ee) values. Except for molecules with mesomeric species, all of the tested enantiomers exhibited high SERS-ChA asymmetry factors (g), ranging between 1.34 and 1.99 regardless of polarities, sizes, chromophores, concentrations and ee. The effect might be attributed to selective resonance coupling between the induced electric and magnetic dipoles associated with enantiomers and chiral plasmonic modes of CNAFs. 相似文献
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MI Ai-Qiao CHEN Yuan-Wei XIAO Xun LIU Shi-Kui WU Lan-Jun JIANG Yao-Zhong Chengdu Institute of Organic Chemistry Academia Sinica Chengdu 《有机化学》1993,(2)
A serious of new pinanone ketimine, and of which asymmetric alkylation, carbonyl additionand double chiral induction reaction have been studied. The ketimine with π-structure are essential toobtain excellent stereoselectivities in 90%~99%e.e. They are explained by the transition model thatwe proposed. 相似文献
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Robert Łysek Ewa Woźny Marek Chmielewski 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2):327-340
Chiral formates derived from propane-1,2-diol, 1,2- O -isopropylidene- f - D -xylo- and f - D -gluco-furanoses were subjected to treatment with cyclopentadienyl [tris(trimethylsilylmethyl)] titanium (IV). A mixture of the corresponding ( E )- and ( Z )- g -silylvinyl ethers were obtained with predominance of the former. It was found that in contrast to ( Z )-vinyl ethers, which give g -lactams with chlorosulfonyl isocyanate, the ( E )-vinyl ethers gave unstable cycloadducts which undergo rapid elimination reaction leading to ( E )- f , g -unsaturated amides. 相似文献
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The separation of enantiomers is of great importance in biology, pharmaceutics, agriculture and environment. The different separation modes ( i. e. capillary zone electrophoresis ( CZE ), micellar electrokinetic chromatography ( MEKC ), capillary electrochromatography ( CEC ), etc ) 相似文献
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GU Jin-ying HE Wan-ping SHI Xian-fa JI Liang-nian 《高等学校化学研究》2008,24(1):106-109
Three novel types of chiral calixarene derivatives 5, 8, and 10 were designed and synthesized by introducing chiral units to parent calixarenes. Their chiralities were confirmed by rotational analysis. Chiral recognition properties of these host compounds towards L- and D-threonine were studied by UV-Vis spectroscopy. The results indicated that calixarene derivatives 5 and 8 exhibited good chiral recognition capabilities toward L- or D-threonine. Although calixarene derivative 10 had no evident chiral recognition ability, the supramolecules of calixarene derivative 10 with L- or D-threonine showed a hypochromic effect or hyperchromic effect respectively. Therefore, calixarene derivative 10 might serve as a good chiral UV-indicator. 相似文献
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Two new chiral calix[4] arenes bearing chiral pendants,which were from by-product of the antibiotic industry,were synthesized and characterized by ^1H NMR.MS-FAB and elemental analysis,Studies of ^1H NMR of the two calix[4] arene derivatives indicate that they exist in cone conformation in solution.Results of chiral recognition of the two chiral ligands 2a and 2b towards the tartaric acid derivative 3 show that ligand 2a exhibited good chiral recognition abilities compared to ligand 2b. 相似文献
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Yong Fei MING Liang ZHAO Hong Li ZHANG Yan Ping SHI Yong Min LI Li Ren CHEN 《中国化学快报》2006,17(9):1213-1216
The increasing demands for the production of enantiomerically pure compounds in the field of pharmacology, chemistry, biotechnology, chemical engineering, etc., have made enantioselective separations to become one of the most important analytical tasks. H… 相似文献
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Anikó Nemes Tamás Csóka Szabolcs Béni Zsófia Garádi Dénes Szabó József Rábai 《Helvetica chimica acta》2020,103(8):e2000081
Four new chiral α-(nonafluoro-tert-butoxy)carboxylic acids were synthesized from naturally occurring α-amino acids (alanine, valine, leucine and isoleucine, respectively), and tested in 1H- and 19F-NMR experiments as chiral NMR shift reagents. The NMR studies were carried out at room temperature, using CDCl3 and C6D6 as solvents, and (RS)-α-phenylethylamine and (RS)-α-(1-naphthyl)ethylamine as racemic model compounds. To demonstrate the applicability of the reagents, the racemic drugs ketamine and prasugrel were also tested. 相似文献
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Bruna S. Santos Sandra C.C. Nunes Alberto A.C.C. Pais Teresa M.V.D. Pinho e Melo 《Tetrahedron》2012,68(19):3729-3737
Chiral spiro-β-lactam derivatives have been prepared via stereoselective 1,3-dipolar cycloaddition of 6-diazopenicillanates. Using dipolarophiles such as acrylonitrile, acrylates or methyl vinyl ketone spiro-2-pyrazoline-β-lactams were obtained, whereas the cycloaddition with N-substituted-maleimides afforded spiro-1-pyrazoline-β-lactams. 6-Diazopenicillanates also reacted with electron-deficient alkynes to give the corresponding spiro-3H-pyrazole-β-lactam as single product. The observed stereoselectivity can be explained considering that the major product results from the addition to the less sterically hindered α-side of the β-lactam. Microwave-induced denitrogenation of spiro-1-pyrazoline-β-lactams allowed the stereoselective synthesis of novel spirocyclopropyl-β-lactams. The rationalization of the observed selectivity was supported by electronic structure calculations. 相似文献
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Dr. Kai Yang Yixian Lou Chenglan Wang Dr. Liang-Wen Qi Tongchang Fang Feng Zhang Hetao Xu Lu Zhou Wangyang Li Guan Zhang Prof. Dr. Peiyuan Yu Prof. Dr. Qiuling Song 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(8):3320-3325
A new chiral Brønsted acid, generated in situ from a chiral phosphoric acid boron (CPAB) complex and water, was successfully applied to asymmetric indole reduction. This “designer acid catalyst”, which is more acidic than TsOH as suggested by DFT calculations, allows the unprecedented direct asymmetric reduction of C2-aryl-substituted N-unprotected indoles and features good to excellent enantioselectivities with broad functional group tolerance. DFT calculations and mechanistic experiments indicates that this reaction undergoes C3-protonation and hydride-transfer processes. Besides, bulky C2-alkyl-substituted N-unprotected indoles are also suitable for this system. 相似文献
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Cai Lian SU Rong Ji DAI Bin TONG Yu Lin DENG 《中国化学快报》2006,17(5):649-652
Chirality plays an important role in the function of biological processes. For isolating only the desired enantiomer, various methods have been developed, such as high performance liquid chromatography and capillary electrophoresis1. But with these method… 相似文献
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In recent years, the synthesis of chiral tetrahedral clusters has been studied extensively and various types are accessible , which are a kind of organometallic compounds with greatly growing interest due to their potential application to asymmetric reaction catalysts. As an efficient 相似文献
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ZHANG Qi-Wei WANG Gui-Xian 《结构化学》2007,26(5):551-554
The title compound, [Cu(dpa)(2,2'-bipy)(H2O)2]n 1 (H2dpa = diphenic acid and 2,2'- bipy = 2,2'-bipyridine), has been synthesized and its structure was determined by single-crystal X-ray diffraction. The crystal is of orthorhombic, space group P212121 with a = 10.597(4), b = 11.317(4), c = 17.630(7) , V = 2114.3(14) 3, C24H20CuN2O6, Mr = 495.97, Z = 4, Dc = 1.558 g/cm3, μ = 1.079 mm-1, F(000) = 1020, Flack value = 0.052(18), R = 0.0430 and wR = 0.1016 for 3381 observed reflections (I > 2σ(I)). In compound 1, the dpa ligands link metal ions into helical structures in the same direction. 相似文献
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Qi-Jun Yao Shuo Zhang Bei-Bei Zhan Prof. Dr. Bing-Feng Shi 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(23):6717-6721
Atroposelective synthesis of axially chiral biaryls by palladium-catalyzed C−H olefination, using tert-leucine as an inexpensive, catalytic, and transient chiral auxiliary, has been realized. This strategy provides a highly efficient and straightforward access to a broad range of enantioenriched biaryls in good yields (up to 98 %) with excellent enantioselectivities (95 to >99 % ee). Kinetic resolution of trisubstituted biaryls bearing sterically more demanding substituents is also operative, thus furnishing the optically active olefinated products with excellent selectivity (95 to >99 % ee, s-factor up to 600). 相似文献