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1.
Diastereo‐ and Enantioselective Palladium‐Catalyzed Dearomative [3+2] Cycloaddition of 3‐Nitroindoles 下载免费PDF全文
Diastereo‐ and enantioselective cycloaddition of 3‐nitroindoles with vinyl aziridine was realized under Pd‐catalysis using commercially available Walphos as the ligand, affording pyrroloindolines in high yields with high diastereo‐ and enantioselectivities. The reaction can be scaled up to a gram scale and the reaction products are easily converted to amino pyrroloindoline and other pyrroloindoline derivatives. 相似文献
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Dr. Vera J. Meyer Christoph Ascheberg Prof. Meike Niggemann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(17):6371-6374
A formal intermolecular [2+2+2] cycloaddition reaction of enynes to aldehydes is presented, which can be realized in the presence of a simple and benign calcium catalyst. The reaction proceeds with excellent chemo, regio‐ and diastereoselectivity and leads to a one‐step assembly of highly interesting bicyclic building blocks containing up to three stereocenters from simple precursors via a new type of skeletal rearrangement of enynes. The observed diastereoselectivity is accounted for by two different mechanistic proposals. The first one engages mechanistic prospects arising from a gold catalyzed reaction in the absence of the stabilizing gold substituent. The second proposal involves an unprecedented cyclization–carbonyl allene ene reaction–hydroalkoxylation cascade. 相似文献
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Palladium(0)‐Catalyzed Intermolecular Allylic Dearomatization of Indoles by a Formal [4+2] Cycloaddition Reaction 下载免费PDF全文
Run‐Duo Gao Qing‐Long Xu Bo Zhang Yiting Gu Prof. Li‐Xin Dai Prof. Dr. Shu‐Li You 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(33):11601-11604
Bridged indoline derivatives were synthesized by an intermolecular Pd‐catalyzed allylic dearomatization reaction of substituted indoles. The reaction between indoles and allyl carbonates bearing a nucleophilic alcohol side‐chain proceeds in a cascade fashion, providing bridged indolines in excellent enantioselectivity. 相似文献
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Zhuo Xin Dr. Søren Kramer Dr. Jacob Overgaard Prof. Dr. Troels Skrydstrup 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(26):7926-7930
A new synthetic route to the privileged 1,2‐dihydroisoquinolines is reported. This method, which relies on a gold‐catalyzed formal [4+2] cycloaddition between ynamides and imines, provides a new retrosynthetic disconnection of the 1,2‐dihydroisoquinoline core by installing the 1,8a C?C and 2,3 C?N bonds in one step. Both aldimines and ketimines can be used as substrates. In addition, one example of dihydrofuropyridine synthesis is also demonstrated. 相似文献
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Rhodium‐Catalyzed Asymmetric Synthesis of Silicon‐Stereogenic Dibenzosiloles by Enantioselective [2+2+2] Cycloaddition 下载免费PDF全文
Dr. Ryo Shintani Chihiro Takagi Tomoaki Ito Dr. Masanobu Naito Prof. Dr. Kyoko Nozaki 《Angewandte Chemie (International ed. in English)》2015,54(5):1616-1620
A rhodium‐catalyzed asymmetric synthesis of silicon‐stereogenic dibenzosiloles has been developed through a [2+2+2] cycloaddition of silicon‐containing prochiral triynes with internal alkynes. High yields and enantioselectivities have been achieved by employing an axially chiral monophosphine ligand, and the present catalysis is also applicable to the asymmetric synthesis of a germanium‐stereogenic dibenzogermole. Preliminary studies on the optical properties of these compounds are also described. 相似文献
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Enantioselective Palladium‐Catalyzed [3+2] Cycloaddition of Trimethylenemethane and Fluorinated Ketones 下载免费PDF全文
Prof. Dr. Barry M. Trost Dr. Guillaume Mata 《Angewandte Chemie (International ed. in English)》2018,57(38):12333-12337
A nitrile‐substituted trimethylenemethane (TMM) donor undergoes palladium‐catalyzed [3+2] cycloadditions with fluorinated ketones to generate tetrasubstituted trifluoromethylated centers in high enantioselectivity under mild conditions. The generation of the palladium–TMM complex was achieved by a self‐deprotonation strategy, which shows remarkable improvements in regiocontrol, efficiency, and atom economy of asymmetric [3+2] cycloadditions. Moreover, the versatility of the nitrile group provides direct access to a variety of synthetically useful intermediates, including amides, aldehydes, and esters. The developed reaction conditions allow for the synthesis of a wide variety of aromatic, heteroaromatic, and aliphatic fluorinated dihydrofurans in excellent regio‐ and enantioselectivities. 相似文献
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Xuelei Jia Honghui Lei Feipeng Han Tao Zhang Ying Chen Zhengshuang Xu Pratanphorn Nakliang Sun Choi Yian Guo Tao Ye 《Angewandte Chemie (International ed. in English)》2020,59(31):12832-12836
A concise and asymmetric total synthesis of five kopsane alkaloids that share a unique heptacyclic caged ring system was accomplished. The key transformation in the sequence involved a remarkable PtCl2‐catalyzed intramolecular [3+2] cycloaddition, which allowed for the rapid assembly of pentacyclic carbon skeletons bearing 2,3‐quaternary functionalized indoline. Expeditious construction of diverse indoline scaffolds with excellent control of diastereoselectivity demonstrated the broad scope and versatility of this key transformation. 相似文献
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Formal Asymmetric Organocatalytic [3+2] Cyclization between Enecarbamates and 3‐Indolylmethanols: Rapid Access to 3‐Aminocyclopenta[b]indoles 下载免费PDF全文
Clément Lebée Dr. Antti O. Kataja Florent Blanchard Dr. Géraldine Masson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(23):8399-8402
A highly enantio‐ and diastereoselective synthesis of 3‐aminocyclopenta[b]indoles has been developed through formal [3+2] cycloaddition reaction of enecarbamates and 3‐indolylmethanols. This transformation is catalyzed by a chiral phosphoric acid that achieves simultaneous activation of both partners of the cycloaddition. Mechanistic data are also presented that suggest that the reaction occurs through a stepwise pathway. 相似文献
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Dr. Qing‐Qing Cheng Lynée A. Massey Brook S. Willett Dr. Yongming Deng Dr. Hadi Arman Prof. Dr. Michael P. Doyle 《Angewandte Chemie (International ed. in English)》2018,57(32):10343-10346
Enoldiazoimides, a new subclass of enoldiazo compounds, generate enol‐substituted carbonyl ylides whose reactions with sulfur ylides enable an unprecedented formal [4+2] cycloaddition. The resulting multifunctionalized indolizidinones, which incorporate sulfur, are formed in good yields under mild reaction conditions. The uniqueness of this transformation stems from the role of the silyl‐protected enol, since the corresponding acetyldiazoimide failed to provide any cross‐products in metal‐catalyzed reactions with sulfur ylides. This copper‐catalyzed cycloaddition is initiated with the generation of enol‐substituted carbonyl ylides and sulfur ylides from enoldiazoimides and sulfonium salts, respectively, and proceeds through stepwise six‐membered ring formation, C?O and C?S bond cleavage, and silyl and acetyl group migration. 相似文献
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Enantio‐ and Diastereoselective Synthesis of Chiral Allenes by Palladium‐Catalyzed Asymmetric [3+2] Cycloaddition Reactions 下载免费PDF全文
Prof. Dr. Barry M. Trost Dr. Daniel Zell Dr. Christoph Hohn Dr. Guillaume Mata Autumn Maruniak 《Angewandte Chemie (International ed. in English)》2018,57(39):12916-12920
A protocol for the asymmetric synthesis of highly substituted chiral allenes with control of point and axial chirality has been developed. A palladium‐catalyzed [3+2] cycloaddition using readily available racemic allenes gives access to densely functionalized chiral allenes with excellent yields and functional group tolerance. The catalytic asymmetric protocol utilizes a broad range of allenyl TMM (trimethylenemethane) donors to form cyclopentanes, pyrrolidines, and spirocycles with very good control of regio‐, enantio‐, and diastereoselectivity. The chiral allene moiety is shown to be a valuable functional group for rapid elaboration towards complex targets. 相似文献
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Dr. Naifu Hu Hoimin Jung Yu Zheng Juhyeong Lee Dr. Lilu Zhang Zakir Ullah Dr. Xiulan Xie Dr. Klaus Harms Prof. Dr. Mu‐Hyun Baik Prof. Dr. Eric Meggers 《Angewandte Chemie (International ed. in English)》2018,57(21):6242-6246
A novel method for the catalytic asymmetric dearomatization by visible‐light‐activated [2+2] photocycloaddition with benzofurans and one example of a benzothiophene is reported, thereby providing chiral tricyclic structures with up to four stereocenters including quaternary stereocenters. The benzofurans and the benzothiophene are functionalized at the 2‐position with a chelating N‐acylpyrazole moiety which permits the coordination of a visible‐light‐activatable chiral‐at‐rhodium Lewis acid catalyst. Computational molecular modeling revealed the origin of the unusual regioselectivity and identified the heteroatom in the heterocycle to be key for the regiocontrol. 相似文献
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Asymmetric “Acetylenic” [3+2] Cycloaddition of Nitrones Catalyzed by Cationic Chiral PdII Lewis Acid 下载免费PDF全文
Highly enantioselective [3+2] cycloaddition of ynones and nitrones has been developed. Very bulky ligand, DTBM‐SEGPHOS, was used for an effective asymmetric induction over distal reaction centers on the linear ynone dipolarophile and for prevention of PdII catalyst deactivation by coordination of the nitrones. The reaction has wide scope of substrates in both ynones and nitrones. 相似文献
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Biming Mao Honglei Liu Zhengyang Yan Yi Xu Jiaqing Xu Wei Wang Yongjun Wu Hongchao Guo 《Angewandte Chemie (International ed. in English)》2020,59(28):11316-11320
A palladium‐catalyzed asymmetric [4+2] cycloaddition of 2‐methylidenetrimethylene carbonate with alkenes derived from pyrazolones, indandione, or barbiturate has been successfully developed, affording pharmacologically interesting chiral tetrahydropyran‐fused spirocyclic scaffolds. The target compounds were generated in good to excellent yields and with high enantioselectivity (up to 99 % ee). Furthermore, this cycloaddition reaction could be efficiently scaled up, and several synthetic transformations were accomplished for the construction of other useful chiral spiropyrazolone and spiroindandione derivatives. 相似文献
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Atom‐Economic Synthesis of Fully Substituted 2‐Aminopyrroles via Gold‐Catalyzed Formal [3+2] Cycloaddition between Ynamides and Isoxazoles 下载免费PDF全文
Xin‐Yu Xiao Ai‐Hua Zhou Chao Shu Fei Pan Dr. Ting Li Prof. Dr. Long‐Wu Ye 《化学:亚洲杂志》2015,10(9):1854-1858
A concise and flexible synthesis of fully substituted 2‐aminopyrroles via gold‐catalyzed formal [3+2] cycloaddition between ynamides and isoxazoles has been developed. Under mild reaction conditions, various 2‐aminopyrrole derivatives were obtained in good to excellent yields, thus providing an efficient and atom‐economic way for the construction of fully substituted 2‐aminopyrroles. 相似文献
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Miao‐Miao Li Qin Xiong Bao‐Le Qu Yu‐Qing Xiao Yu Lan Liang‐Qiu Lu Wen‐Jing Xiao 《Angewandte Chemie (International ed. in English)》2020,59(40):17429-17434
Vinylcyclopropanes (VCPs) are commonly used in transition‐metal‐catalyzed cycloadditions, and the utilization of their recently realized reactivities to construct new cyclic architectures is of great significance in modern synthetic chemistry. Herein, a palladium‐catalyzed, visible‐light‐driven, asymmetric [5+2] cycloaddition of VCPs with α‐diazoketones is accomplished by switching the reactivity of the Pd‐containing dipolar intermediate from an all‐carbon 1,3‐dipole to an oxo‐1,5‐dipole. Enantioenriched seven‐membered lactones were produced with good reaction efficiencies and selectivities (23 examples, 52–92 % yields with up to 99:1 er and 12.5:1 dr). In addition, computational investigations were performed to rationalize the observed high chemo‐ and periselectivities. 相似文献