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在可回收手性配体[ QN(OH)2]2PHAL的催化下,通过不对称氨羟化或双羟化反应合成紫杉醇13-C侧链,两种方法的产率分别为39%,97%ee和52%,99%ee,其结构经1H NMR,IR和元素分析确证. 相似文献
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在AlCl3和多聚磷酸的存在下, 以邻苯二甲酸酐和对二氟苯为原料, 通过Friedel-Crafts和环化反应, 用改进的方法以60%的产率生成1,4-二氟蒽醌. 然后通过奎宁锂与1,4-二氟蒽醌的亲核取代反应得到新型手性配体(QN)2AQN, 产率85%. 在氧化-供氮试剂N-氯代氨基甲酸苄酯存在下, (QN)2AQN与OsO4原位生成的催化剂在五种肉桂酸甲酯的不对称氨羟化反应中表现出优异的对映选择性(90%~96% ee)和一般至优秀的区域选择性(75∶25~98∶2), 产率50%~70%, 高于文献报道的结果. 该手性配体易于合成, 成本低廉, 用于催化不对称氨羟化反应, 可以制备光学活性的α-氨基酸酯类化合物. 相似文献
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ZnFe2O4中阳离子分布对苯酚H2O2羟化制苯二酚催化活性的影响 总被引:2,自引:0,他引:2
具有尖晶石结构的铁酸盐是苯酚H2O2羟化合成苯二酚的有效催化剂.分别用共沉淀和水热法制备了ZnFe2O4,并用Mossbauer,XRD和ESR等方法予以表征.发现不同方法制备的ZnFe2O4中阳离子在四面体和八面体位置的分布不同,认为阳离子分布影响了催化活性. 相似文献
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四氧化锇催化的不对称双羟基化反应 总被引:1,自引:0,他引:1
本文综述了近年来四氧化锇催化不对称双羟基化的研究进展。在诸多改进的方法中以铁氰化钾为共氧化剂和以金鸡纳生物碱酯为手性配体的OsO_4催化不对称双羟化为最好,对映体过量一般在90%以上,化学产率为80—95%,我们首次将这个不对称双羟化用于构成植物生长调节剂油菜甾体的双羟基侧链,获得令人满意的结果。 相似文献
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一种均相催化、两相回收的手性配体的合成及其催化烯烃不对称双羟化反应 总被引:1,自引:0,他引:1
在金鸡纳生物碱衍生物配体存在下,四氧化锇催化的烯烃的不对称双羟化反应(AD)已广泛用于手性药物、精细化学品和天然产物的合成.AD反应也是合成抗癌药物紫杉醇C13-片段的实用方法之一.然而,由于配体和四氧化锇价格昂贵以及锇的毒性限制了AD反应的工业生产.近年来,在 相似文献
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Resin-OsO4-金鸡纳生物碱:一种在(E)-二苯乙烯不对称双羟化反应中可循环使用的高效催化剂 总被引:1,自引:0,他引:1
用改进的方法把季铵盐共价结合在Merrifield树脂上作为离子交换剂与K2O5O4作用制成Resin—OsO4催化剂,在NaH存在下,以DMF作溶剂,在70℃下奎宁或奎尼丁与1,4-二氯二氮杂萘反应高产率地生成(QN)2PHAL或(QD)2PHAL,Resin—OsO4通过简单过滤可定量回收,回收的催化剂重复使用五次,其活性不变,Resin—OsO4-(QN)2PHAL或(QD)2PHAL催化体系在(E)-二苯乙烯的不对称双羟化反应中的化学产率为84~91%,立体选择性为96-99%ee。 相似文献
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研究了双功能手性硫脲-叔胺催化剂催化的3-苯基异香豆冉酮衍生物与N-保护亚胺的不对称Mannich反应,高收率、高对映选择性(88%~98%)地合成了一系列具有连续季碳叔碳手性中心的新化合物,其结构经1HNMR和13C NMR表征。 相似文献
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Manuel Kirchhof Karina Abitaev Abdulwahab Abouhaileh Katrin Gugeler Dr. Wolfgang Frey Dr. Anna Zens Prof. Johannes Kästner Prof. Thomas Sottmann Prof. Sabine Laschat 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(68):16853-16870
Microemulsions provide a unique opportunity to tailor the polarity and liquid confinement in asymmetric catalysis via nanoscale polar and nonpolar domains separated by a surfactant film. For chiral diene Rh complexes, the influence of counterion and surfactant film on the catalytic activity and enantioselectivity remained elusive. To explore this issue chiral norbornadiene Rh(X) complexes (X=OTf, OTs, OAc, PO2F2) were synthesized and characterized by X-ray crystallography and theoretical calculations. These complexes were used in Rh-catalyzed 1,2-additions of phenylboroxine to N-tosylimine in microemulsions stabilized either exclusively by n-octyl-β-D-glucopyranoside (C8G1) or a C8G1-film doped with anionic or cationic surfactants (AOT, SDS and DTAB). The Rh(OAc) complex showed the largest dependence on the composition of the microemulsion, yielding up to 59 % (90 %ee) for the surfactant film doped with 5 wt% of AOT as compared to 52 % (58 %ee) for neat C8G1 at constant surfactant concentration. Larger domains, determined by SAXS analysis, enabled further increase in yield and selectivity while the reaction rate almost remained constant according to kinetic studies. 相似文献
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Wang Haoran Wang Zhi Zhang Hong Chen Ge Yue Hong 《Green Chemistry Letters and Reviews》2014,7(2):145-149
The asymmetric aldol addition of 2-butanone and 4-nitrobenzaldehyde catalyzed by a novel thermophilic esterase (APE1547) from the archaeon Aeropyrum pernix K1 was successfully conducted in organic solvents. APE1547 exhibited a good enzyme activity and enantioselectivity in the reaction. The effects of organic solvent, temperature, water content, and substrate concentration were investigated. The reaction provided optically active secondary alcohol with satisfying enantioselectivity (71.2 %ee) and enzyme activity (38.1 µmol/g/h) under the optimum conditions. A high yield (68.7%) could be obtained when the reaction time was approximately 120 h. 相似文献
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In the current study, a convenient and simple way is presented to synthesize a novel type of supported heterogeneous organocatalyst in 21-81% yield by the copolymerization of 9-amino-9-deoxy-epi-cinchonine organocatalyst with acrylonitrile using AIBN as radical initiator. The chemical compositions (x/y) and weight-average molecular weights of copolymers 1a-d were determined by (1)H NMR and GPC analysis respectively. Their porous and layered structure, and surface morphology were characterized by nitrogen adsorption-desorption, XRD and TEM. In the asymmetric aldol addition of p-nitrobenzaldehyde to cyclohexanone and 1-hydroxy-2-propanone in water, all the supported organocatalysts 1a-d afforded excellent isolated yields (90.2-94.7%) and stereoselectivities (96.8-97.8%ee anti, anti/syn = 91/9). The highest catalytic property (96% yield, anti/syn = 90/10 and 99%ee anti) in water as the sole solvent was achieved under the optimized conditions. Compared with cyclohexanone, cyclopentanone and acetone showed the less desired enantioselectivities in the same aldol reactions. At the end of the aldol reaction, the copolymer-supported organocatalyst 1a was readily recovered in 95-98% yield from reaction mixture by simple filtration using an organic membrane. Even in the fifth run, there was no significant loss in catalytic activity and stereocontrol (94.3% yield, 97.2%ee anti, anti/syn = 90/10). After continuous reuse five times, there was some drop in catalytic activity and stereoselectivity. 相似文献
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《Tetrahedron: Asymmetry》2014,25(24):1581-1589
(R)-Tetrahydrothiophene-3-ol sulfonyl derivatives 3–19 were prepared by introduction of various sulfonyl groups at the hydroxyl group of (R)-tetrahydrothiophene-3-ol 1 with low enantiomeric purity (68–74% ee). Crystallization was applied to improve their enantiomeric purity. Improvement in enantiomeric purity depended on the introduced sulfonyl group. The enantiomeric purity of enantiomeric sulfonyl derivatives was improved to more than 90% ee by simple crystallization without using seed crystals. These products from crystallization provided not only higher %ee crystals but also a higher %ee mother liquor. The enantiomeric purity of diastereomeric sulfonyl derivatives was improved remarkably, and the product of the derivative 18 provided the mother liquor with 100% de. Crystallization of these sulfonyl derivatives showed a novel and interesting feature that mother liquors with high enantiomeric purity were obtained in many cases. 相似文献