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1.
PyBidine/Copper Catalyst: Asymmetric exo′‐Selective [3+2] Cycloaddition using Imino Ester and Electrophilic Indole 下载免费PDF全文
Dr. Atsuko Awata Prof. Dr. Takayoshi Arai 《Angewandte Chemie (International ed. in English)》2014,53(39):10462-10465
Electrophilic indoles having two electron‐withdrawing groups undergo nucleophilic attack at C2 and electrophilic functionalization at C3. This is the first enantioselective formal [3+2] cycloaddition using electrophilic indoles. The PyBidine/Cu catalyst smoothly promoted highly enantio‐ and exo′‐selective [3+2] cycloaddition using imino esters and 3‐nitroindoles. This reaction provides a method for the preparation of diverse and complex chiral pyrroloindoline compounds. 相似文献
2.
Enantioselective Formal [4+2] Cycloadditions to 3‐Nitroindoles by Trienamine Catalysis: Synthesis of Chiral Dihydrocarbazoles 下载免费PDF全文
Yang Li Dr. Fernando Tur Rune Pagh Nielsen Dr. Hao Jiang Prof. Dr. Frank Jensen Prof. Dr. Karl Anker Jørgensen 《Angewandte Chemie (International ed. in English)》2016,55(3):1020-1024
The first enantioselective formal [4+2] cycloadditions of 3‐nitroindoles are presented. By using 3‐nitroindoles in combination with an organocatalyst, chiral dihydrocarbazole scaffolds are formed in moderate to good yields (up to 87 %) and enantioselectivities (up to 97 % ee). The reaction was extended to include enantioselective [4+2] cycloadditions of 3‐nitrobenzothiophene. The reaction proceeds through a [4+2] cycloaddition/elimination cascade under mild reaction conditions. Furthermore, a diastereoselective reduction of an enantioenriched cycloadduct is presented. The mechanism of the reaction is discussed based on experimental and computational studies. 相似文献
3.
Stereodivergent Synthesis of Tetrahydrofuroindoles through Pd‐Catalyzed Asymmetric Dearomative Formal [3+2] Cycloaddition 下载免费PDF全文
Qiang Cheng Dr. Fang Zhang Yue Cai Prof. Dr. Yin‐Long Guo Prof. Dr. Shu‐Li You 《Angewandte Chemie (International ed. in English)》2018,57(8):2134-2138
A stereodivergent synthesis of tetrahydrofuroindoles through palladium‐catalyzed asymmetric dearomative formal [3+2] cycloaddition of nitroindoles with epoxybutenes was developed. The polarity of the solvent was found to play a key role in the diastereoselectivity. In toluene, good to excellent yields (70–99 %), diastereoselectivity (87/13‐>95/5 d.r.), and enantioselectivity (85/15–94/6 e.r.) were obtained, regardless of the properties of the substituents on nitroindoles. In acetonitrile, tetrahydrofuroindoles of a different diastereoisomer were produced with good to excellent yields (75–98 %) and stereoselectivity (78/22–93/7 d.r., 93/7–99/1 e.r.). Mechanistic studies were conducted to illustrate the origin of the diastereodivergency. The kinetic experiments indicate that the rate‐determining step of this reaction is different in different solvents. ESI‐MS experiments also support the existence of key palladium complex intermediates and the catalytic cycle of the reaction. 相似文献
4.
Kaizhi Li Tho P. Gonalves Kuo‐Wei Huang Yixin Lu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(16):5481-5485
The dearomatization of 3‐nitroindoles through a chiral‐phosphine‐mediated [3+2] annulation reaction is described. This method makes use of readily available 3‐nitroindoles as an aromatic feedstock and rapidly delivers a wide range of cyclopentaindoline alkaloid scaffolds in a highly enantioselective manner. Notably, phosphine‐triggered cyclization has not been utilized previously in a dearomatization process. 相似文献
5.
RhCl(PPh3)3‐catalyzed [4+2] intramolecular cycloaddition of optically active axially chiral allene‐dienes afforded cis‐fused [3.4.0]‐bicyclic products with three chiral centers in good yields with an excellent chemo‐ and diastereoselectivity. A pair of enantiomers of such products was generated highly selectively from both enantiomers of starting allene‐dienes, indicating that the axial chirality dictated the absolute configurations of the three in situ generated chiral centers with a very high efficiency of chirality transfer. 相似文献
6.
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
7.
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
8.
Asymmetric Brønsted Base Catalyzed and Directed [3+2] Cycloaddition of 2‐Acyl Cycloheptatrienes with Azomethine Ylides 下载免费PDF全文
Vibeke H. Lauridsen Lise Ibsen Jakob Blom Prof. Dr. Karl Anker Jørgensen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(10):3259-3263
Conjugated cyclic trienes have the potential for different types of cycloaddition reactions. In the present work, we will, in a novel asymmetric cycloaddition reaction, demonstrate that the organocatalytic reaction of 2‐acyl cycloheptatrienes with azomethine ylides proceeds as a [3+2] cycloaddition, which is in contrast to the Lewis acid‐catalyzed reaction, in which a [3+6] cycloaddition takes place. In the presence of a chiral organosuperbase, 2‐acyl cycloheptatrienes react in a highly enantioselective manner in the [3+2] cycloaddition with azomethine ylides, providing the 1,3‐dipolar cycloaddition product in high yields and up to 99 % ee. It is also shown that the diene formed by the reaction can undergo stereoselective dihydroxylation, bromination, and cycloaddition reactions. Finally, based on experimental observations, some mechanistic considerations are discussed. 相似文献
9.
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
10.
Conghui Tang Mikiko Okumura Yunbo Zhu Annie R. Hooper Yu Zhou Yu‐Hsuan Lee David Sarlah 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(30):10351-10355
A protocol for palladium‐catalyzed dearomative functionalization of simple, nonactivated arenes with Grignard reagents has been established. This one‐pot method features a visible‐light‐mediated [4+2] cycloaddition between an arene and an arenophile, and subsequent palladium‐catalyzed allylic substitution of the resulting cycloadduct with a Grignard reagent. A variety of arenes and Grignard reagents can participate in this process, forming carboaminated products with exclusive syn‐1,4‐selectivity. Moreover, the dearomatized products are amenable to further elaborations, providing functionalized alicyclic motifs and pharmacophores. For example, naphthalene was converted into sertraline, one of the most prescribed antidepressants, in only four operations. Finally, this process could also be conducted in an enantioselective fashion, as demonstrated with the desymmetrization of naphthalene. 相似文献
11.
Catalytic Enantioselective and Regioselective [3+3] Cycloadditions Using 2‐Indolylmethanols as 3 C Building Blocks 下载免费PDF全文
Xiao‐Xue Sun Hong‐Hao Zhang Guo‐Hao Li Ying‐Ying He Prof. Dr. Feng Shi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(49):17526-17532
The first catalytic asymmetric cycloaddition using 2‐indolylmethanols as 3C building blocks has been established by a chiral phosphoric acid‐catalyzed enantioselective and regioselective [3+3] cycloaddition of 2‐indolylmethanols with azomethine ylides, which constructed biologically important tetrahydro‐γ‐carboline frameworks in high yields and excellent enantioselectivities (up to 83 % yield, 99:1 e.r.). This reaction not only represents the first application of 2‐indolylmethanols as 3C building blocks in catalytic asymmetric cycloadditions, but also has established an abnormal regioselectivity in indolylmethanol‐involved transformations. 相似文献
12.
Xin Wang Mengxue Lu Qin Su Minghui Zhou Yesu Addepalli Weijun Yao Zhen Wang Yixin Lu 《化学:亚洲杂志》2019,14(19):3409-3413
Amino‐acid‐derived phosphine catalyzed [4+2] cycloaddition leading to chiral tetrahydropyridines, making use of α‐substituted allenic ketones as “C4 synthons” and N‐sulfonyl cyclic ketimines, has been developed. This asymmetric cycloaddition tolerates a wide range of α‐substituted allenic ketones. A series of chiral sultam‐fused tetrahydropyridines bearing a quaternary stereocenter were obtained in high yields with good enantioselectivities. 相似文献
13.
Stereoselective Construction of 1,3‐Disilylcyclopentane Derivatives by Scandium‐Catalyzed [3+2] Cycloaddition of Allylsilanes to β‐Silylenones 下载免费PDF全文
Dr. Kazuhiro Okamoto Eisuke Tamura Prof. Dr. Kouichi Ohe 《Angewandte Chemie (International ed. in English)》2014,53(38):10195-10199
The Sc(OTf)3‐catalyzed [3+2] cycloaddition of allylsilanes to β‐silyl‐α,β‐unsaturated ketones (β‐silylenones) has been developed to form five‐membered syn‐1,3‐disilylketones diastereoselectively through the rearrangement of the silicon substituents on the allylsilane. Stabilization of the carbocation intermediates by a double silicon effect plays a key role in directing the course of the reaction to favor the [3+2] cycloaddition pathway over simple allylation. 相似文献
14.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(9):2509-2512
A novel cascade reaction has been developed for the synthesis of 2,6‐methanopyrrolo[1,2‐b]isoxazoles based on the gold‐catalyzed generation of an N‐allyloxyazomethine ylide. This reaction involves sequential [3+2]/retro‐[3+2]/[3+2] cycloaddition reactions, thus providing facile access to fused and bridged heterocycles which would be otherwise difficult to prepare using existing synthetic methods. Notably, this reaction allows the efficient construction of three C−C bonds, one C−O bond, one C−N bond and one C−H bond, as well as the cleavage of one C−C bond, one C−O bond and one C−H bond in a single operation. The intermolecular cycloaddition of an N‐allyloxyazomethine ylide and the subsequent application of the product to the synthesis of tropenol is also described. 相似文献
15.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(40):12460-12464
Highly selective divergent cycloaddition reactions of enoldiazo compounds and α‐diazocarboximides catalyzed by copper(I) or dirhodium(II) have been developed. With tetrakis(acetonitrile)copper(I) tetrafluoroborate as the catalyst epoxypyrrolo[1,2‐a]azepine derivatives were prepared in good yields and excellent diastereoselectivities through the first reported [3+3]‐cycloaddition of a carbonyl ylide. Use of Rh2(pfb)4 or Rh2(esp)2 directs the reactants to regioselective [3+2]‐cycloaddition generating cyclopenta[2,3]pyrrolo[2,1‐b]oxazoles with good yields and excellent diastereoselectivities. 相似文献
16.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(30):8793-8797
Previously reported was that cis‐ene‐vinylcyclopropanes (cis‐ene‐VCPs) underwent Rh‐catalyzed [5+2] reaction to give 5,7‐fused bicyclic products, where vinylcyclopropane (VCP) acts as five‐carbon synthon. Unfortunately, this reaction had very limited scope. Replacing the 2π component of cis‐ene‐VCPs to allene moiety, the corresponding cis‐allene‐VCPs did not undergo the expected normal [5+2] cycloaddition to give 5,7‐fused bicyclic products. Instead, the challenging bicyclo[4.3.1]decane skeleton was obtained via an unprecedented bridged [5+2] cycloaddition. DFT calculations were applied to understand why this bridged [5+2] reaction is favored over the anticipated but not realized normal [5+2] reaction. 相似文献
17.
Rhodium‐Catalyzed Intramolecular [3+2+2] Cycloadditions between Alkylidenecyclopropanes,Alkynes, and Alkenes 下载免费PDF全文
Marisel Araya Moisés Gulías Dr. Israel Fernández Dr. Gaurav Bhargava Prof. Luis Castedo Prof. José Luis Mascareñas Dr. Fernando López 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(33):10255-10259
A Rh‐catalyzed intramolecular [3+2+2] cycloaddition is reported. The cycloaddition affords synthetically relevant 5,7,5‐fused tricyclic systems of type 2 from readily available dienyne precursors. The transformation takes place with moderate or good yields, high diastereoselectivity, and total chemoselectivity. 相似文献
18.
A Highly Efficient Chirality Switchable Synthesis of Dihydropyran‐Fused Benzofurans by Fine‐Tuning the Phenolic Proton of β‐Isocupreidine (β‐ICD) Catalyst with Methyl 下载免费PDF全文
Feng Wang Chen Yang Dr. Xiao‐Song Xue Prof. Dr. Xin Li Jin‐Pei Cheng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(29):10443-10449
A highly enantioselective β‐isocupreidine (β‐ICD) catalyzed synthesis of dihydropyran‐fused benzofurans through [4+2] cycloaddition of allenoates and benzofuranone alkenes was developed. Switchable chirality inversion of cycloaddition products was achieved by replacing the phenolic proton of the catalyst with a methyl, demonstrating an amazing effect of minimal structural variation on inverting enantioselectivity. DFT calculations were utilized to elucidate the origin of the observed phenomena. Computation also provided a clue for a rational design in which the multi‐hydrogen bond with the alcohol additive was found to improve the enantioselectivity of the cycloaddition. Finally, the substrate scope was examined, in which a number of functionalized dihydropyran‐fused benzofurans could be obtained in high yields (up to 97 %) with very good regio‐ (>20:1) and enantioselectivities (up to 98:2 e.r.). 相似文献
19.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(26):7587-7591
The first asymmetric [3+1]‐cycloaddition was successfully achieved by copper(I) triflate/double‐sidearmed bisoxazoline complex catalyzed reactions of β‐triisopropylsilyl‐substituted enoldiazo compounds with sulfur ylides. This methodology delivered a series of chiral cyclobutenes in good yields with high enantio‐ and diastereoselectivities (up to 99 % ee , and >20:1 d.r.). Additionally, the [3+1]‐cycloaddition of catalytically generated metallo‐enolcarbenes was successfully extended to reaction with a stable benzylidene dichlororuthenium complex. 相似文献
20.
NHC‐Catalyzed Asymmetric Synthesis of Functionalized Succinimides from Enals and α‐Ketoamides 下载免费PDF全文
Dr. Lei Wang Qijian Ni Marcus Blümel Tao Shu Prof. Dr. Gerhard Raabe Prof. Dr. Dieter Enders 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(22):8033-8037
The efficient asymmetric synthesis of highly substituted succinimides from α,β‐unsaturated aldehydes and α‐ketoamides via NHC‐catalyzed [3+2] cycloaddition has been developed. The new scalable protocol significantly expands the utility of NHC catalysis for the synthesis of heterocycles and provides easy access to assemble a wide range of succinimides from simple starting materials. 相似文献