共查询到20条相似文献,搜索用时 15 毫秒
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A concise and flexible stereoselective route to synthesize both enantiomers of the highly functionalized α,β-unsaturated-δ-lactones, altholactone and isoaltholactone, from readily available cinnamyl alcohol is described. This approach derived its asymmetry from Sharpless catalytic asymmetric epoxidation and Sharpless asymmetric dihydroxylation reactions. The resulting diols were produced in high enantiomeric excess and were cyclized in a stereoselective manner in the presence of a catalytic amount of camphor sulphonic acid. 相似文献
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Comely AC Eelkema R Minnaard AJ Feringa BL 《Journal of the American Chemical Society》2003,125(29):8714-8715
A novel integrated bio- and chemocatalytic approach to the de novo catalytic asymmetric synthesis of saccharides has been developed. Acetoxypyranones obtained enantiopure by enzymatic resolution have been shown to undergo highly stereoselective palladium-catalyzed formal O-glycoside bond formation. The combination of these protocols can be applied to the iterative asymmetric catalytic synthesis of saccharides. 相似文献
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Ma JA 《Chemical Society reviews》2006,35(7):630-636
Catalytic asymmetric reactions provide one of the most powerful and economical synthetic approaches to a variety of enantiomerically enriched compounds. As being analogues of the corresponding alpha- and beta-amino acids, optically active alpha- and beta-amino phosphonic acid derivatives have found widespread use in medicinal chemistry and the pharmaceutical sciences. Using catalytic amounts of chiral materials, asymmetric synthesis of enantiomerically enriched alpha- and beta-amino phosphonates has been a subject of growing interest. This tutorial review contains a compilation of the catalytic asymmetric synthetic methods developed to date and highlights their utility for obtaining these target compounds. 相似文献
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Kumagai N 《Chemical & pharmaceutical bulletin》2011,59(1):1-22
The development of atom-economical catalytic asymmetric reactions based on two distinct sets of catalyst, a rare earth metal/amide-based ligand catalyst and a soft Lewis acid/hard Br?nsted base catalyst, is reviewed. These catalytic systems exhibit high catalytic activity and stereoselectivity by harnessing a cooperative catalysis through hydrogen bond/metal coordination and soft-soft interactions/hard-hard interactions, respectively. The effectiveness of these cooperative catalysts is clearly delineated by the high stereoselectivity in reactions with highly coordinative substrates, and the specific activation of otherwise low-reactive pronucleophiles under proton transfer conditions. The rare earth metal/amide-based ligand catalyst was successfully applied to catalytic asymmetric aminations, nitroaldol (Henry) reactions, Mannich-type reactions, and conjugate addition reactions, generating stereogenic tetrasubstituted centers. Catalytic asymmetric amination and anti-selective catalytic asymmetric nitroaldol reactions were successfully applied to the efficient enantioselective synthesis of therapeutic candidates, such as AS-3201 and the β(3)-adrenoreceptor agonist, showcasing the practical utility of the present protocols. The soft Lewis acid/hard Br?nsted base cooperative catalyst was specifically developed for the chemoselective activation of soft Lewis basic allylic cyanides and thioamides, which are otherwise low-reactive pronucleophiles. The cooperative action of the catalyst allowed for efficient catalytic generation of active carbon nucleophiles in situ, which were integrated into subsequent enantioselective additions to carbonyl-type electrophiles. 相似文献
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Gui-Ling Zhao 《Tetrahedron letters》2006,47(28):4929-4932
A short, direct, catalytic, enantioselective synthesis of polyketide segments and carbohydrates is presented. The novel, direct, one-pot, organocatalytic asymmetric tandem cross-aldol/Horner-Wittig-Emmons reactions assemble polyketide and carbohydrate derivatives in good yield with 93-98% ee. The one-pot catalytic asymmetric tandem reaction was applied to a highly enantioselective formal de novo synthesis of the rare carbohydrate, l-altrose. 相似文献
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Gröger H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2001,7(24):5246-5251
Bifunctional catalysts can drastically improve the efficiency of asymmetric processes with respect to enantioselectivity and/or conversion rate. A new type of chiral bifunctional catalyst has been developed recently in the Shibasaki group that contains both Lewis acid and Lewis base moieties. These monometallic and bifunctional phosphinoyl-containing catalysts are able to coordinate both nucleophilic and electrophilic substrates in the transition state. Several successful applications of this new catalytic concept in the field of asymmetric cyanation reactions have already been reported, for example, the asymmetric hydrocyanation of aldehydes and imines as well as the asymmetric Reissert reaction. The development and principle of this catalytic concept as well as main applications thereof are reviewed in this article. 相似文献
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《Tetrahedron: Asymmetry》2014,25(20-21):1401-1408
The bis(hydroxyphenyl)diamide architecture constitutes as a privileged ligand that promotes a number of catalytic asymmetric transformations in combination with rare-earth metals. A new diamide analog armed with a carbene catalytic function derived from a thiazolium unit was designed, synthesized, and applied to the catalytic asymmetric intramolecular Stetter reaction. Cooperative work between the carbene function and hydrogen bonding interactions was suggested to give the enantioenriched chroman derivatives. 相似文献
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Meng Sun Chun Ma Si‐Jia Zhou Sai‐Fan Lou Jian Xiao Yinchun Jiao Feng Shi 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(26):8795-8800
The first catalytic asymmetric (4+3) cyclization of in situ generated ortho‐quinone methides with 2‐indolylmethanols has been established, which constructed seven‐membered heterocycles in high yields (up to 95 %) and excellent enantioselectivity (up to 98 %). This approach not only represents the first catalytic asymmetric (4+3) cyclization of o‐hydroxybenzyl alcohols, but also enabled an unprecedented catalytic asymmetric (4+3) cyclization of 2‐indolylmethanols. In addition, a scarcely reported catalytic asymmetric (4+3) cyclization of para‐quinone methide derivatives was accomplished. 相似文献
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Expansion of the Concept of Nonlinear Effects in Catalytic Reactions Beyond Asymmetric Catalysis
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Dipl.‐Ing. Robert Pollice Prof. Dr. Michael Schnürch 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(16):5637-5642
The observation and investigation of nonlinear effects in catalytic reactions provides valuable mechanistic insight. However, the applicability of this method was, until now, limited to molecules possessing chirality and therefore to asymmetric synthesis. The concept of nonlinear effects is expanded to catalytic reactions beyond asymmetric catalysis by using derivatives instead of enantiomers and by considering rates instead of enantiomeric excess. Additionally, its systematic application to investigate the mechanism of catalytic reactions is presented. By exceeding the limitation to asymmetric reactions, the study of nonlinear effects can become a general tool to elucidate reaction mechanisms. 相似文献
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Nucleophilic and Electrophilic Activation of Non‐Heteroaromatic Amides in Atom‐Economical Asymmetric Catalysis
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Dr. Naoya Kumagai Prof. Dr. Masakatsu Shibasaki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(43):15192-15200
Recent advances in catalytic asymmetric carbon–carbon bond‐forming reactions of non‐heteroaromatic amide substrates are highlighted. Among carbonyl compounds, amides have received limited attention in catalytic asymmetric transformations mainly owing to their lower reactivity. Amides are reluctant to form enolates for nucleophilic addition, and α,β‐unsaturated amides exhibit diminished electrophilicity at the β‐carbon. Recent advances in asymmetric catalysis rendered these amides amenable to enantioselective reactions with perfect atom economy, producing synthetically useful chiral building blocks. This Minireview summarizes recent developments in the field. 相似文献
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Yoshihiro Sohtome Dr. Nobuko Takemura Keisuke Takada Rika Takagi Toshitsugu Iguchi Kazuo Nagasawa Prof. Dr. 《化学:亚洲杂志》2007,2(9):1150-1160
Catalytic enantio‐ and diastereoselective nitroaldol reactions were explored by using designed guanidine–thiourea bifunctional organocatalysts under mild and operationally simple biphasic conditions. These catalytic asymmetric reactions have a broad substrate generality with respect to the variety of aldehydes and nitroalkanes. Based on this catalytic nitroaldol process, straightforward syntheses of cytoxazone and 4‐epi‐cytoxazone were achieved. These catalytic nitroaldol reactions require KI as an additive for highly asymmetric induction; it operates by inhibiting the retro mode of the reaction. On the basis of studies of structure and catalytic‐activity relationships, a plausible guanidine–thiourea cooperative mechanism and a transition state of the catalytic reactions are proposed. Drastic substituent effects on the catalytic properties of this catalyst may lead to the development of new chiral surfactants. 相似文献
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Several novel planar chiral phosphinocyrhetrenyloxazolines have been synthesized, and their catalytic activities have been evaluated in a variety of asymmetric catalytic reactions. Preferable effects as compared to their ferrocenyl analogues have been observed in asymmetric allylic amination and asymmetric hydrosilylation, and up to 97% ee and 72% ee were reached, respectively. The Lewis basicity of the phosphorus on the ferrocene and the cyrhetrene, which contributes to their different behavior in catalysis, has been deduced by 31P NMR spectroscopy analysis, as indicated by 1J(77Se-31P) in the corresponding phosphine selenides. 相似文献
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The catalytic asymmetric synthesis of 3,3-disubstituted oxindoles, a big family of privileged scaffolds in natural products and drugs, is of current interest. Recently, the catalytic asymmetric functionalization of diazooxindoles emerges as a potentially general and flexible strategy for this purpose, with several notable examples coming out in 2013. In this digest, synthetic applications of diazooxindoles have been summarized and discussed, which might be helpful for readers to understand the special properties of this type of donor/acceptor cyclic diazo reagent and to develop new catalytic asymmetric reactions. 相似文献
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Chun‐Xiang Zhuo Prof. Dr. Wei Zhang Prof. Dr. Shu‐Li You 《Angewandte Chemie (International ed. in English)》2012,51(51):12662-12686
This Review summarizes the development of catalytic asymmetric dearomatization (CADA) reactions. The CADA reactions discussed herein include oxidative dearomatization reactions, dearomatization by Diels–Alder and related reactions, the alkylative dearomatization of electron‐rich arenes, transition‐metal‐catalyzed dearomatization reactions, cascade sequences involving asymmetric dearomatization as the key step, and nucleophilic dearomatization reactions of pyridinium derivatives. Asymmetric dearomatization reactions with chiral auxiliaries and catalytic asymmetric reactions of dearomatized substrates are also briefly introduced. This Review intends to provide a concept for catalytic asymmetric dearomatization. 相似文献
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FENG Xiaoming 《高等学校化学研究》2001,17(3)
Chiral titanium complexes is very importance catalyst to asymmetric catalytic reactions. A series of catalytic systems based on titanium-chiral ligands complexes has been reported. This presentation will discuss some of our recent progress on asymmetric catalytic reactions catalyzed by chiral titanium complexes. 相似文献
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Kengo Oka Shunsuke Fuchi Dr. Keita Komine Dr. Hayato Fukuda Prof. Dr. Susumi Hatakeyama Prof. Dr. Jun Ishihara 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(56):12862-12867
The catalytic asymmetric total synthesis of (−)-exiguolide, a complex 20-membered macrolide embedded with a bis(tetrahydropyran) motif, is reported. The convergent synthesis involves the construction of the C1–C11 tetrahydropyran segment via catalytic asymmetric allylation and Prins cyclization, and the formation of the C12–C21 phosphonate segment via catalytic asymmetric cyclocondensation reaction and Johnson–Claisen rearrangement. The synthesis of 15-epi-exiguolide is also described. 相似文献