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1.
The first investigation on catalytic asymmetric [2,3]-sigmatropic rearrangement of sulfur ylides generated from carbenoids and allenic phenyl sulfide was carried out. Up to 55% ee value was obtained. 相似文献
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ZHANG Xiao-Mei MA Ming Wang Jian-Bo 《有机化学》2003,23(Z1):19-20
The catalytic asymmetric reactions of oxygen or sulfur ylides generated from carbenoids have attracted consider able attention in recent years. High enantioselectivities have been achieved in the 1,3-dipolar cycloaddition reactions and [ 2,3 ]-sigmatropic rearrangement of oxygen ylides. In contrast to the oxygen ylide, the corresponding catalytic asymmetric reaction of sulfur ylide is less developed. Compared to oxygen ylides, the sulfur ylides are more stable and experimental evidence supports a free ylide rather than a metal-bound ylide as reaction intermediate. That means the enantio-control must be in the step of the ylide formation. If the subsequent reaction such as [ 2,3 ]-sigmatropic rearrangement or 1,3-dipolar cycloaddition is a concerted process and is faster than the racemization of the chiral ylide intermediate, then the catalytic asymmetric sulfur ylide reaction will be possible. 相似文献
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报道烯(炔)基硫醚与α-重氮羰基化合物, 在[RuCl2(p-cymene)]2催化下, 经由金属卡宾发生硫叶立德[2,3]-σ重排反应(Doyle-Kirmse反应). 在Ru(II)作用下, α-重氮羰基化合物与烯丙基硫醚的反应以较好收率生成相应的[2,3]-σ重排产物高烯丙基硫醚. 同样条件下与炔丙基硫醚的反应则生成[2,3]-σ重排产物联烯和呋喃衍生物, 后者是联烯进一步在Ru(II)作用下重排的产物. 相似文献
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Varinder K. Aggarwal Alison Thompson Ray V.H. Jones Mike C.H. Standen 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):361-362
Abstract: This paper describes a new method for the preparation of aziridines from imines and diazocompounds which requires catalytic amounts of metal salts and sulfides and operates under neutral conditions. Using enantiomerically pure sulfides, high enantioselectivity has been achieved in the aziridination process. 相似文献
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首次研究了Cu(CH3CN)4BF4/DTBM-BIPHEP催化的亚甲胺叶立德与环丙基亚甲基乙酸乙酯参与的不对称1,3-偶极环加成反应,获得了优异的exo-选择性,研究结果证实大空间位阻的手性双膦配体对反应的非对映选择性控制起到至关重要的影响;同时一步高效构建三个叔碳手性中心和一个螺环季碳中心. 该不对称1,3-偶极环加成反应收率良好,得到优秀的非对映(>98:2,dr)与对映选择性(ee值高达99%). 该催化体系为合成exo构型的5-氮杂-螺[2,4]庚烷衍生物提供了一种简洁高效的方法,具有原子经济性好、反应条件温和、底物适用范围广等优点. 相似文献
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Mohammed Anif Pasha Dr. Swamy Peraka Prof. Dr. Dhevalapally B. Ramachary 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(41):10563-10568
Lawsone aldehydes were directly transformed into the biologically important, unique carbon skeleton of chiral methanobenzo[f]azulenes/methanodibenzo[a,d][7]annulenes in high dr and ee and in very good yields by using quinine-thiourea-catalyzed tandem Wittig/intramolecular Michael/intramolecular aldol reactions. This asymmetric catalytic tandem protocol will be highly useful because these final molecules are basic skeletons of important antibiotics. 相似文献
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Patrick Metzner Jean-François Brière Hiroya Takada 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4):965-968
Abstract The reaction of novel chiral selenonium and telluronium ylides was investigated with aldehydes and compared to the sulfur analogues. (2R,5R)-2,5-Dimethylselenolane was prepared and reacted as a catalyst for the benzylidenation of aldehydes. Disubstituted epoxides were readily prepared with a (surprising) absence of diastereoselectivity, and with enantiomeric excesses higher than 90%. The reaction of a tellurium analogue, (2S,5S)-2,5-diethyltellurolane, afforded the oxirane in very moderate yield and e.e.'s in the range of 62–82%. Though this was less productive, it is the first report of a chiral telluronium ylide leading to an asymmetric epoxidation of aldehydes. 相似文献
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Zhenfa Zhang 《Tetrahedron letters》2011,52(21):2667-2669
Expeditious syntheses of cis-1-methyl-2,3,3a,4,5,9b-hexahydro-1H-pyrrolo-[3,2h]isoquinoline/[2,3-f]quinoline have been developed. The syntheses started with commercially available materials and afforded excellent overall yields in straightforward steps. Intramolecular azomethine ylide-alkene [3+2] cycloaddition is the key step in the construction of these pyrroloisoquinoline and pyrroloquinoline scaffolds. This route is much more atom-economic than those reported in the literature and is appropriate for scale-up synthesis. 相似文献
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Diethyl thiopyrano[2,3-d]pyrimidine-6,7-dicarboxylates 2a, b ; thiopyrano[23-d]pyrimidines 3a-c and 4a-c thieno[2,3-d]pyrimidine-6-carbonitriles 5a-c and thieno[2, 3-d]pyrimidine-6-carboxamides 5d-f have been prepared. 相似文献
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Total Synthesis of Proposed Structure of Yuremamine and All Diastereomers Using [3+2]‐Cycloaddition of Platinum‐Containing Azomethine Ylide 下载免费PDF全文
Tomoya Ohyama Masako Uchida Prof.Dr. Hiroyuki Kusama Prof. Dr. Nobuharu Iwasawa 《化学:亚洲杂志》2015,10(9):1850-1853
Total synthesis of the proposed structure of yuremamine has been achieved for the first time based on the intermolecular [3+2]‐cycloaddition reaction of the platinum‐containing azomethine ylide. All the possible diastereomers of yuremamine were also synthesized via the common intermediate. Through these syntheses, it was confirmed that the proposed structure of yuremamine and the diastereomers differ from the natural product. 相似文献
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A simple and powerful one-pot reaction method was developed for the synthesis of heteracalixaromatics. In the presence of a base, one-pot macrocyclic condensation reaction between cyanuric chloride and 1,3-phenylene diols and diamines proceeded effectively under very mild conditions to afford a number of functionalised oxygen and nitrogen-bridged calix[2]arene[2]triazines in 33–54% yields. The method was applied in a multigram-scale (14.4 g) preparation of tetraoxacalix[2]arene[2]triazine. 相似文献
16.
Xian-Tao An Dr. Ji-Yuan Du Zhi-Long Jia Qing Zhang Ke-Yin Yu Yi-Zhou Zhang Dr. Xian-He Zhao Prof. Dr. Ran Fang Prof. Dr. Chun-An Fan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(17):3803-3809
Palladium-catalyzed asymmetric [4+5] annulation of ortho-quinone methides (o-QMs) with substituted vinylethylene carbonates (VECs) is described for the first time, giving a novel enantioselective approach to chiral nine-membered benzoheterocycles. Based on this designed [4+5] annulation, an unprecedented silica gel-promoted tandem rearrangement reaction featuring a unique asymmetric aromatic Claisen rearrangement is explored at room temperature, offering a new method for asymmetric construction of all-carbon quaternary stereocenters embedded in chiral functionalized homoallylic alcohols. 相似文献
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Dr. Oleksandr Zhurakovskyi Dr. Yunus E. Türkmen Lorenz E. Löffler Vijayalakshmi A. Moorthie C. Chun Chen Michael A. Shaw Mark R. Crimmin Marco Ferrara Dr. Mushtaq Ahmad Dr. Mehrnoosh Ostovar Johnathan V. Matlock Prof. Dr. Varinder K. Aggarwal 《Angewandte Chemie (International ed. in English)》2018,57(5):1346-1350
A convergent, nine‐step (LLS), enantioselective synthesis of α‐cyclopiazonic acid and related natural products is reported. The route features a) an enantioselective aziridination of an imine with a chiral sulfur ylide; b) a bioinspired (3+2)‐cycloaddition of the aziridine onto an alkene; and c) installation of the acetyltetramic acid by an unprecedented tandem carbonylative lactamization/N?O cleavage of a bromoisoxazole. 相似文献
18.
Dr. Han-Han Kong Dr. Long Zhao Dr. Hong-Ling Pan Prof. Ming-Wu Ding 《European journal of organic chemistry》2023,26(13):e202300127
A new one-pot preparation of dibenzo[b,e]azepin-6(11H)-one by a sequential Ugi-4CR and sulfur ylide-mediated rearrangement reaction has been developed. A series of polysubstituted dibenzo[b,e]azepin-6(11H)-ones were obtained in 69–84 % yields from readily available sulfonium salts, 2-aminophenyl ketones, aldehydes and isocyanides in the presence of DBU. 相似文献
19.
A novel ammonium template containing three ammonium sites was synthesized. Two ammoniums located on the linear component served as template for cucurbit[6]uril to form the CB-based pseudo[2]rotacane while another one located on the macrocyclic component played a role of template for clipping reaction. As a result of a ‘‘threading-followed-by-clipping' approach, a novel hetero pseudo[2]rota[2]catenane was successfully constructed. 相似文献
20.
The chiral phosphoric acid catalyzed asymmetric[3+2]annulation of substituted 2-vinylindoles with azlactones has been established.This reaction represented a practical approach for the synthesis of structurally diverse pyrrolo[1,2-a]indoles with two vicinal stereocenters including one tetrasubstituted stereocenter in good yields and good stereoselectivities under mild conditions. 相似文献