共查询到20条相似文献,搜索用时 15 毫秒
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Hong‐Cheng Shen Yu‐Feng Wu Ying Zhang Lian‐Feng Fan Prof. Dr. Zhi‐Yong Han Prof. Dr. Liu‐Zhu Gong 《Angewandte Chemie (International ed. in English)》2018,57(9):2372-2376
A PdII‐catalyzed asymmetric aminohydroxylation of 1,3‐dienes with N‐tosyl‐2‐aminophenols was developed by making use of a chiral pyridinebis(oxazoline) ligand. The highly regioselective reaction provides direct and efficient access to chiral 3,4‐dihydro‐2H‐1,4‐benzoxazines in high yield and enantioselectivity (up to 96:4 e.r.). The reaction employs readily available N‐tosyl‐2‐aminophenols as a unique aminohydroxylation reagent and is complementary to known asymmetric aminohydroxylation methods. 相似文献
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Dr. Xu Deng Shao‐Fei Ni Zheng‐Yu Han Yu‐Qing Guan Prof. Dr. Hui Lv Prof. Dr. Li Dang Prof. Dr. Xu‐Mu Zhang 《Angewandte Chemie (International ed. in English)》2016,55(21):6295-6299
An enantioselective rhodium(I)‐catalyzed cycloisomerization reaction of challenging (E)‐1,6‐enynes is reported. This novel process enables (E)‐1,6‐enynes with a wide range of functionalities, including nitrogen‐, oxygen‐, and carbon‐tethered (E)‐1,6‐enynes, to undergo cycloisomerization with excellent enantioselectivity, in a high‐yielding and operationally simple manner. Moreover, this RhI‐diphosphane catalytic system also exhibited superior reactivity and enantioselectivity for (Z)‐1,6‐enynes. A rationale for the striking reactivity difference between (E)‐ and (Z)‐1,6‐enynes using RhI‐BINAP and RhI‐TangPhos is outlined using DFT studies to provide the necessary insight for the design of new catalyst systems and the application to synthesis. 相似文献
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Giulia Erre Kathrin Junge Dr. Stephan Enthaler Dr. Daniele Addis Dirk Michalik Dr. Anke Spannenberg Dr. Matthias Beller Prof. Dr. 《化学:亚洲杂志》2008,3(5):887-894
New monodentate H8‐binaphthol based phosphoramidites 6 b–i have been prepared. Starting from (S)‐3,3′‐dibromo‐5,5′,6,6′,7,7′,8,8′‐octahydro‐1,1′‐binaphthyl‐2,2′‐diol 3 , a general protocol for the synthesis of ligands 6 is presented. A small ligand library bearing aryl substituents in the 3,3′‐position of the binaphthol core was synthesized and successfully tested in the iridium‐catalyzed asymmetric hydrogenation of 2‐amidocinnamates to obtain different α‐amino acid derivatives in up to 99 % ee. 相似文献
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Cationic Ir/Me‐BIPAM‐Catalyzed Asymmetric Intramolecular Direct Hydroarylation of α‐Ketoamides 下载免费PDF全文
Tomohiko Shirai Prof. Dr. Hajime Ito Prof. Dr. Yasunori Yamamoto 《Angewandte Chemie (International ed. in English)》2014,53(10):2658-2661
Asymmetric intramolecular direct hydroarylation of α‐ketoamides gives various types of optically active 3‐substituted 3‐hydroxy‐2‐oxindoles in high yields with complete regioselectivity and high enantioselectivities (84–98 % ee). This is realized by the use of the cationic iridium complex [Ir(cod)2](BArF4) and the chiral O‐linked bidentate phosphoramidite (R,R)‐Me‐BIPAM. 相似文献
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1,6-烯炔底物在过渡金属催化剂作用下的化学行为得到了广泛的研究,重点是关于过渡金属催化的1,6-烯炔环异构化反应.从反应机理角度入手,把1,6-烯炔环异构化反应按启动方式总结为三类,并对这三种方式启动的1,6-烯炔环异构化反应进行了详细地总结和阐述. 相似文献
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Jun He Yuhang Xue Bo Han Chunzhu Zhang You Wang Shaolin Zhu 《Angewandte Chemie (International ed. in English)》2020,59(6):2328-2332
Starting from diverse alkene‐tethered aryl iodides and O‐benzoyl‐hydroxylamines, the enantioselective reductive cross‐electrophilic 1,2‐carboamination of unactivated alkenes was achieved using a chiral pyrox/nickel complex as the catalyst. This mild, modular, and practical protocol provides rapid access to a variety of β‐chiral amines with an enantioenriched aryl‐substituted quaternary carbon center in good yields and with excellent enantioselectivities. This process reveals a complementary regioselectivity when compared to Pd and Cu catalysis. 相似文献
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Asymmetric Hydroalkoxylation of Non‐Activated Alkenes: Titanium‐Catalyzed Cycloisomerization of Allylphenols at High Temperatures 下载免费PDF全文
M. Sc. Johannes Schlüter M. Sc. Max Blazejak Dr. Florian Boeck Prof. Dr. Lukas Hintermann 《Angewandte Chemie (International ed. in English)》2015,54(13):4014-4017
The asymmetric catalytic addition of alcohols (phenols) to non‐activated alkenes has been realized through the cycloisomerization of 2‐allylphenols to 2‐methyl‐2,3‐dihydrobenzofurans (2‐methylcoumarans). The reaction was catalyzed by a chiral titanium–carboxylate complex at uncommonly high temperatures for asymmetric catalytic reactions. The catalyst was generated by mixing titanium isopropoxide, the chiral ligand (aS)‐1‐(2‐methoxy‐1‐naphthyl)‐2‐naphthoic acid or its derivatives, and a co‐catalytic amount of water in a ratio of 1:1:1 (5 mol % each). This homogeneous thermal catalysis (HOT‐CAT) gave various (S)‐2‐methylcoumarans with yields of up to 90 % and in up to 85 % ee at 240 °C, and in 87 % ee at 220 °C. 相似文献
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Enantioselective Synthesis of All‐Carbon Quaternary Stereogenic Centers via Copper‐Catalyzed Asymmetric Allylic Alkylation of (Z)‐Allyl Bromides with Organolithium Reagents 下载免费PDF全文
Dr. Martín Fañanás‐Mastral Dr. Romina Vitale Dr. Manuel Pérez Prof. Dr. Ben L. Feringa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(11):4209-4212
A copper/phosphoramidite catalyzed asymmetric allylic alkylation of Z trisubstituted allyl bromides with organolithium reagents is reported. The reaction affords all‐carbon quaternary stereogenic centers in high yields and very good regio‐ and enantioselectivity. This systematic study illustrates the crucial role of the olefin geometry of the allyl substrate on the outcome of the reaction and provides a viable alternative to access these important structural motifs. 相似文献
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Gold‐Catalyzed 6‐Exo‐Dig Cycloisomerization: A Versatile Approach to Functionalized Phenanthrenes 下载免费PDF全文
A novel gold‐catalyzed 6‐exo‐dig cycloisomerization of o‐propargylbiaryls has been developed that provides ready access to functionalized phenanthrenes in largely good to excellent yields. Notable features of this method are readily available starting materials, mild reaction conditions, and broad substrate scope. 相似文献
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Gold‐Catalyzed Diastereoselective Cycloisomerization of Alkylidene‐Cyclopropane‐Bearing 1,6‐Diynes 下载免费PDF全文
Dr. Hongchao Zheng Laura L. Adduci Dr. Ryan J. Felix Prof. Dr. Michel R. Gagné 《Angewandte Chemie (International ed. in English)》2014,53(30):7904-7907
An unprecedented gold‐catalyzed diastereoselective cycloisomerization of 1,6‐diynes bearing an alkylidene cyclopropane moiety has been developed. This methodology enables rapid access to a variety of 1,2‐trimethylenenorbornanes, which are important building blocks in the preparations of abiotic and sesquiterpene core structures. 相似文献
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Gui‐Ling Zhao Dr. Farman Ullah Dr. Luca Deiana Shuangzheng Lin Dr. Qiong Zhang Junliang Sun Prof. Dr. Ismail Ibrahem Dr. Pawel Dziedzic Armando Córdova Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(5):1585-1591
The first examples of one‐pot highly chemo‐ and enantioselective dynamic kinetic asymmetric transformations (DYKATs) involving α,β‐unsaturated aldehydes and propargylated carbon acids are presented. These DYKATs, which proceed by a combination of catalytic iminium activation, enamine activation, and Pd0‐catalyzed enyne cycloisomerization, give access to functionalized cyclopentenes with up to 99 % ee and can be used for the generation of all‐carbon quaternary stereocenters. 相似文献
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Haiyan Xu Peng Yang Pratanphorn Chuanprasit Hajime Hirao Jianrong Zhou 《Angewandte Chemie (International ed. in English)》2015,54(17):5112-5116
We report the use of nickel catalysts for the catalytic transfer hydrogenation of hydrazones and other ketimines with formic acid. Strongly donating bisphosphines must be used to support the catalysts. As in enzymatic catalysis, attractive weak interactions may be important for stereochemical control by the nickel/binapine catalyst. 相似文献
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Gold(I)‐Catalyzed Intramolecular Cycloisomerization of Propargylic Esters with Furan Rings 下载免费PDF全文
Jin‐Ming Yang Prof. Dr. Xiang‐Ying Tang Prof. Dr. Min Shi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(12):4534-4540
A gold‐catalyzed intramolecular cycloisomerization of α‐yne‐furans 1 is described in this contribution. A variety of cyclic α,β‐unsaturated aldehyde or ketone derivatives and nitrogen‐containing tricyclic adducts were obtained selectively in moderate to excellent yields under mild conditions by varying the substituents on the standard substrates. 相似文献
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Ana M. Sanjuán Dr. Muhammad A. Rashid Dr. Patricia García‐García Dr. Alberto Martínez‐Cuezva Dr. Manuel A. Fernández‐Rodríguez Dr. Félix Rodríguez Prof. Dr. Roberto Sanz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(7):3042-3052
Indenes and related polycyclic structures have been efficiently synthesized by gold(I)‐catalyzed cycloisomerizations of appropriate ortho‐(alkynyl)styrenes. Disubstitution at the terminal position of the olefin was demonstrated to be essential to obtain products originating from a formal 5‐endo‐dig cyclization. Interestingly, a complete switch in the selectivity of the cyclization of o‐(alkynyl)‐α‐methylstyrenes from 6‐endo to 5‐endo was observed by adding an alcohol to the reaction media. This allowed the synthesis of interesting indenes bearing an all‐carbon quaternary center at C1. Moreover, dihydrobenzo[a]fluorenes can be obtained from substrates bearing a secondary alkyl group at the β‐position of the styrene moiety by a tandem cycloisomerization/1,2‐hydride migration process. In addition, diverse polycyclic compounds were obtained by an intramolecular gold‐catalyzed alkoxycyclization of o‐(alkynyl)styrenes bearing a nucleophile in their structure. Finally, the use of a chiral gold complex allowed access to elusive chiral 1H‐indenes in good enantioselectivities. 相似文献