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手性钛配合物催化不对称反应研究 总被引:4,自引:0,他引:4
手性钛配合物是一类很有用的手性催化剂,在许多反应中显示出了良好的催化活性和高的对映选择性。在我们研究的系列反应中,发现手性钛配合物是一类优良的手性催化剂,其中不对称催化杂Diels-Alder反应制备二氢吡喃酮(99%ee),不对称催化硫醚氧化成亚砜反应(96%ee)和不对称催化硅腈化反应(87%ee),都获得了好的催化活性和高的对映选择性。我们对以上反应中其催化剂的用量、溶剂、催化剂浓度和抗衡离子的Lewis酸碱性、底物的结构与对映选择性的关系、催化循环机理等进行了较系统、深入的研究,发现非共价相互作用和分子识别现象在不对称催化反应中显示出重要的作用,为进一步设计新的手性催化剂,发展不对称催化反应提供了基础数据。 相似文献
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手性有机分子催化剂在不对称催化中的应用 总被引:2,自引:0,他引:2
近三十年来,不对称催化研究获得了迅猛发展[1].按手性催化剂的种类分,一般可分为手性有机金属配合物催化以及路易斯酸、碱等手性有机分子催化.手性有机金属配合物催化剂在不对称还原、不对称氧化等官能团转化反应中的应用,已达到实用阶段;不使用金属的有机分子催化剂由于其对环境友好,也日益被重视,有机合成化学中十分重要的碳-碳键形成反应,如Aldol反应、Diels-Alder反应等,近年来发表了很多使用手性有机分子催化剂的成功的实例.早在1971年Wiechert[2]等人曾以脯氨酸为催化剂,用于分子内不对称醇醛缩合(Aldol)反应,1974年Hajos[3]等… 相似文献
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研究了一种结构新颖、合成路线简单的手性二胺催化的Diels-Alder反应,考察了各种Br nsted酸助催化剂、温度、溶剂和手性二胺分子中不同的取代基对反应的影响.研究结果表明:该类催化剂在催化Diels-Alder反应中表现出较高的催化活性和中等的立体选择性. 相似文献
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各种手性三齿席夫碱与金属(钛, 铬, 钒, 铁, 铜, 铝)形成的络合物,在催化醛的硅腈化、Diels-Alder、Aldol、杂ene、硫化物的氧化等不对称反应中具有良好的催化活性和对映选择性;其中一些催化体系已成功的应用于天然产物的全合成中,该研究取得了系统性的研究成果。本文综述了手性三齿席夫碱金属络合物在不对称催化反应中的研究进展,同时,探讨了催化剂结构和反应条件对其催化活性和对映选择性的影响。 相似文献
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A Supramolecular Chiral Auxiliary Approach: “Remote Control” of Stereochemistry at a Hierarchically Assembled Dimeric Helicate
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David Van Craen Prof. Dr. Markus Albrecht Prof. Dr. Gerhard Raabe Fangfang Pan Prof. Dr. Kari Rissanen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(10):3255-3258
Dimeric hierarchically‐assembled titanium(IV) helicates are in solvent‐dependent equilibrium with the corresponding monomers. Statistically formed mixtures of such complexes bearing chiral stereocontrolling ligands and achiral diene‐substituted ligands show high diastereoselectivity and reasonable enantioselectivity in the Diels–Alder reaction with maleimides if the reaction proceeds with the dimer but not with the monomer. Thus, solvent dependent switching between the monomer and dimer enables on/off switching of the enantioselectivity. 相似文献
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Takehiko Nishio Yasuhiro Kodama Yuji Tsurumi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(5-6):1449-1450
Abstract New chiral ligands, bis-thiazoline derivatives (sulfur analogues of known oxazolines) were prepared from chiral bis-(N-acylamino alcohols) with Lawesson's reagent. Bis-thiazolines thus obtained proved to be useful chiral ligands for metal in asymmetric Diels–Alder reaction. 相似文献
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New chiral amino acid-derived α-acyloxynitroso reagents for asymmetric nitroso Diels–Alder reactions
Hailing Li Didier Gori Cyrille Kouklovsky Guillaume Vincent 《Tetrahedron: Asymmetry》2010,21(11-12):1507-1510
The preparation of new chiral α-acyloxynitroso derivatives 4a–e as chiral dienophiles for the nitroso Diels–Alder reaction is reported. These compounds are obtained from amino acid-derived iodobenzene dicarboxylates and ketoximes, and are stable and easy-to-handle reagents. Initial studies for their nitroso Diels–Alder reactions with cyclohexadiene are also reported. 相似文献
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Shinji Harada Saki Nakashima Shihori Sekino Wakana Oishi Atsushi Nishida 《化学:亚洲杂志》2020,15(4):483-486
Lanthanide triflates and a series of hexadentate chiral ligand complexes were synthesized. X‐ray‐quality crystals were obtained from mixtures of the lanthanide complexes, which were helical in shape. The complexes showed Lewis acidity and catalyzed the enantioselective Diels–Alder reaction of electron‐rich siloxydienes. The complexes were stable enough to be stored at ambient temperature on a laboratory bench and retained their Lewis acidity even after a month. 相似文献
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Chiral Dawson‐Type Hybrid Polyoxometalate Catalyzes Enantioselective Diels–Alder Reactions
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Wen‐Jing Xuan Dr. Candice Botuha Prof. Bernold Hasenknopf Prof. Serge Thorimbert 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(46):16512-16516
Can achiral organocatalysts linked to chiral polyanionic metal oxide clusters provide good selectivity in enantioselective C?C bond formations? The answer to this question is investigated by developing a new active hybrid polyoxometalate‐based catalyst for asymmetric Diels–Alder reaction. Chirality transfer from the chiral anionic polyoxometalate to the covalently linked achiral imidazolidinone allows Diels–Alder cycloaddition products to be obtained with good yields and high enantioselectivities when using cyclopentadiene and acrylaldehydes as partners. 相似文献
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Dr. Xin-Qi Zhu Dr. Qian Wang Prof. Dr. Jieping Zhu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(1):e202214925
We report herein the first examples of chiral phosphoric acid-catalyzed enantioselective Diels–Alder reactions between 2-trifluoroacetamido-1,3-dienes 1 and α,β-unsaturated carbonyl compounds 2 . Polysubstituted 1-acetamido cyclohexenes 3 were formed in high yields with excellent diastereo- and enantioselectivities. The reaction proceeds through a stepwise process as shown by deuterium labelling experiments. A catalytic enantioselective three-component reaction of 1 , 2 and ortho-hydroxybenzhydryl alcohols 4 was subsequently developed furnishing the densely functionalized hexahydroxanthenes 5 in a highly stereoselective manner. This multicomponent reaction generates four chemical bonds with concurrent creation of five contiguous stereocenters. 相似文献
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A series of novel chiral C2-symmetric bis (oxazoline) ligands have been synthesized.The copper and magnesium complexes,prepared in situ from copper(Ⅱ)-triflate of magnesium triflate with the new enantiopure oxazoline ligands,were evaluated as chiral catalysts in the enantioselective Diels-Alder reaction of cyclopentadiene with N-crotenoyl-oxazolidin-2-one.Primary results showed that diastereoselectivity up to 94% and enantioselectivity up to 68% ee for endo products were observed respectively with these ligands. 相似文献
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Cationic Chiral Pd‐Catalyzed “Acetylenic” Diels–Alder Reaction: Computational Analysis of Reversal in Enantioselectivity
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《化学:亚洲杂志》2018,13(19):2842-2846
The highly enantioselective Diels–Alder reaction of acetylenic dienophiles is shown to be effectively catalyzed by cationic chiral palladium complexes. Not only the degree but also the sense of enantioselectivity critically depends on the steric demand of ligands. Computational analyses indicate that the steric demand does not affect the endo/exo‐selectivity but the enantioface selectivity of dienes. 相似文献
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Haifeng Zheng Yan Wang Chaoran Xu Qian Xiong Lili Lin Xiaoming Feng 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(16):5381-5385
We report the combination of transition‐metal‐catalyzed diversified cycloisomerization of 1,6‐enynes with chiral Lewis acid promoted asymmetric Diels–Alder reaction to realize asymmetric cycloisomerization/Diels–Alder relay reactions of 1,6‐enynes with electron‐deficient alkenes. A broad spectrum of chiral [5,6]‐bicyclic products could be acquired in high yields (up to 99 %) with excellent diastereoselectivy (>19:1 dr) and enantioselectivity (up to 99 % ee). 相似文献
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Jianguang Han Xia Li Yong Guan Wenjun Zhao Prof. Dr. William D. Wulff Prof. Dr. Xiaoguang Lei 《Angewandte Chemie (International ed. in English)》2014,53(35):9257-9261
The first enantioselective total syntheses of prenylflavonoid Diels–Alder natural products (?)‐kuwanon I, (+)‐kuwanon J, (?)‐brosimone A, and (?)‐brosimone B have been accomplished from a common intermediate based on a concise synthetic strategy. Key elements of the synthesis include a biosynthesis‐inspired asymmetric Diels–Alder cycloaddition mediated by a chiral ligand/boron Lewis acid, as well as a process involving regioselective Schenck ene reaction, reduction, and dehydration to realize a biomimetic dehydrogenation for generation of the required diene precursor. Furthermore, a remarkable tandem inter‐/intramolecular asymmetric Diels–Alder cycloaddition process was applied for the synthesis of (?)‐brosimone A. 相似文献