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1.
Phosphine‐Catalyzed Annulations of 4,4‐Dicyano‐2‐Methylenebut‐3‐enoates with Maleimides and Maleic Anhydride
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Xiao‐Nan Zhang Gen‐Qiang Chen Dr. Xiang‐Ying Tang Dr. Yin Wei Dr. Min Shi 《Angewandte Chemie (International ed. in English)》2014,53(40):10768-10773
A novel phosphine‐catalyzed [4+1] annulation of maleimides with 4,4‐dicyano‐2‐methylenebut‐3‐enoates has been developed to afford spirocyclic products, and the maleimides serves as C1 synthons. Moreover, a phosphine‐catalyzed formal [3+2] annulation between 4,4‐dicyano‐2‐methylenebut‐3‐enoates and maleic anhydride has been also achieved, and maleic anhydride behaved as a C3 synthon in the reaction, thus efficiently affording the functionalized cyclopentenones. A stable phosphinium‐containing zwitterionic compound is the key reactive intermediate in both annulations and was successfully isolated. Plausible mechanisms have been proposed on the basis of control experiments and deuterium‐labeling experiments. 相似文献
2.
in this work, the phosphine-catalyzed annulation reactions between modified allylic derivatives and polar 1,1-dicyano-1,3-dienes have been studied. In the catalysis of PPh3 (20 mol%), a [4 + 1 ] annulation reaction is realized between a series of l,l-dicyano-2,4-diaryl-1,3-dienes and ethoxycarbonyl-activated allylic acetate, producing polysubstituted cyclopentenes in modest to excellent yields. It is also observed that the substituents of both 1,3-dienes and allylic derivatives have a significant influence on the annulation mode: under the catalysis of PPh3 or PBu3 (20 mol%), regioselective [3 + 2] annulation products are formed from differently substituted substratcs. 相似文献
3.
Erqing Li Prof. Dr. You Huang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(12):3520-3527
A novel strategy that involves phosphine‐catalyzed sequential [2+3] and [3+2] annulation reactions was developed. In this domino reaction, γ‐substituted allenoates were used as novel C4 synthons, and the bicyclic cyclopenta[b]dihydrofuran derivatives were produced in good to excellent diastereoselectivities and yields under mild conditions. Furthermore, preliminary studies on an asymmetric variant of this reaction proceeded with moderate enantioselectivity. 相似文献
4.
In contrast with the reported phosphine‐ and DABCO‐catalyzed [3+2] and [2+2] annulation of allenoates with trifluoromethylketone, the [2+2+2] annulation of allenoates and two molecules of trifluoromethylketone was found under the condition of N‐heterocyclic carbene catalysis. 相似文献
5.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(45):14410-14414
The first highly enantioselective phosphine‐catalyzed formal [4+4] annulation has been developed. In the presence of amino‐acid‐derived phosphines, the unprecedented [4+4] annulations between benzofuran/indole‐derived α,β‐unsaturated imines and allene ketones proceeded smoothly, thus affording azocines, bearing either a benzofuran or an indole moiety, in excellent yields and with nearly perfect enantioselectivities (≥98 % ee in most cases). This work marks the first efficient asymmetric construction of optically enriched eight‐membered rings by phosphine catalysis. 相似文献
6.
Unusual Formal [1+4] Annulation through Tandem P(NMe2)3‐Mediated Cyclopropanation/Base‐Catalyzed Cyclopropane Rearrangement: Facile Syntheses of Cyclopentenimines and Cyclopentenones
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Dr. Rong Zhou Kai Zhang Ling Han Yusong Chen Prof. Dr. Ruifeng Li Prof. Dr. Zhengjie He 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(17):5883-5887
An unusual formal [1+4] annulation of α‐dicarbonyl compounds with 1,1‐dicyano‐1,3‐dienes has been realized, leading to facile syntheses of cyclopentenimines and cyclopentenones in a unique manner. Mechanistic investigation implies that this reaction takes place through a P(NMe2)3‐mediated cyclopropanation followed by a base‐catalyzed cyclopropane rearrangement. It therefore represents an unprecedented [1+4] annulation mode involving Kukhtin–Ramirez adducts. 相似文献
7.
Skeletal Rearrangement in the ZnII‐Catalyzed [4+2]‐Annulation of Disubstituted N‐Hydroxy Allenylamines with Nitrosoarenes to Yield Substituted 1,2‐Oxazinan‐3‐one Derivatives
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Pankaj Sharma Prof. Dr. Rai‐Shung Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(44):15881-15887
This work reports zinc‐catalyzed [4+2]‐annulation reactions of disubstituted N‐hydroxy allenylamines with nitrosoarenes to afford substituted 1,2‐oxazinan‐3‐ones with a skeletal rearrangement. This annulation is applicable to a reasonable scope of allenylamines and nitrosoarenes. Our control experiments indicate that nitrosobenzene can also implement this annulation through a radical annulation path, but with poor efficiency. Zn(OTf)2 or AgOTf greatly improves the efficiency of this [4+2]‐annulation; the effect of these metal species is discussed in detail. 相似文献
8.
Catalyst‐Controlled Switch in Chemo‐ and Diastereoselectivities: Annulations of Morita–Baylis–Hillman Carbonates from Isatins
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Gu Zhan Ming‐Lin Shi Qing He Wei‐Jia Lin Dr. Qin Ouyang Dr. Wei Du Prof. Dr. Ying‐Chun Chen 《Angewandte Chemie (International ed. in English)》2016,55(6):2147-2151
Regulating both the chemo‐ and diastereoselectivity, divergently, of a reaction is highly attractive but extremely challenging. Presented herein is a catalyst‐controlled switch in the chemo‐ and diastereodivergent annulation reactions of Morita–Baylis–Hillman carbonates, derived from isatins and 2‐alkylidene‐1H‐indene‐1,3(2H)‐diones, in exclusive α‐regioselectivity. α‐Isocupreine efficiently catalyzed [2+1] reactions to access cyclopropane derivatives, and the diastereodivergent [3+2] annulations were accomplished by employing either a chiral phosphine or a DMAP‐type molecule. All reactions exhibited excellent chemoselectivities, and good to remarkable stereoselectivities were furnished, thus leading to a collection of compounds with skeletal and stereogenic diversity. Moreover, DFT computational calculations elucidated the catalyst‐based switch in mechanism. 相似文献
9.
《中国化学》2017,35(9):1469-1473
A phosphine‐catalyzed [4 + 2] annulation of α ‐substituted allenoate with exocyclic alkene moiety of oxindoles or indan‐1,3‐diones has been developed. Thus, under the catalysis of PPh3 (20 mol%), a series of spirooxindole‐ or spiroindan‐1,3‐dione‐cyclohexenes have been obtained in moderate to excellent yields and regioselectivity from the annulations of α ‐methyl allenoates with 3‐methyleneoxindoles or 2‐methyleneindan‐1,3‐diones. This method offers an easy access to structurally novel spirocyclohexenes. 相似文献
10.
Selective Oxidative [4+2] Imine/Alkene Annulation with H2 Liberation Induced by Photo‐Oxidation
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Xia Hu Guoting Zhang Faxiang Bu Prof. Aiwen Lei 《Angewandte Chemie (International ed. in English)》2018,57(5):1286-1290
The oxidative [4+2] annulation reaction represents an elegant and versatile synthetic protocol for the construction of six‐membered heterocyclic compounds. Herein, a photoinduced oxidative [4+2] annulation of NH imines and alkenes was developed by utilizing a dual photoredox/cobaloxime catalytic system. Various multisubstituted 3,4‐dihydroisoquinolines can be obtained in good yields. This method is not only obviated the need of stiochiometric amounts of oxidants but also exhibited excellent atom economy by generating H2 as the only byproduct. Remarkably, high regioselectivity and trans diastereoselectivity can be achieved in this transformation even if the Z/E mixture of alkenes were employed. 相似文献
11.
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
12.
Biphenyl‐Derived Phosphepines as Chiral Nucleophilic Catalysts: Enantioselective [4+1] Annulations To Form Functionalized Cyclopentenes
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Daniel T. Ziegler Lorena Riesgo Takuya Ikeda Yuji Fujiwara Prof. Gregory C. Fu 《Angewandte Chemie (International ed. in English)》2014,53(48):13183-13187
Because of the frequent occurrence of cyclopentane subunits in bioactive compounds, the development of efficient catalytic asymmetric methods for their synthesis is an important objective. Introduced herein is a new family of chiral nucleophilic catalysts, biphenyl‐derived phosphepines, and we apply them to an enantioselective variant of a useful [4+1] annulation. A range of one‐carbon coupling partners can be employed, thereby generating cyclopentenes which bear a fully substituted stereocenter [either all‐carbon or heteroatom‐substituted (sulfur and phosphorus)]. Stereocenters at the other four positions of the cyclopentane ring can also be introduced with good stereoselectivity. An initial mechanistic study indicates that phosphine addition to the electrophilic four‐carbon coupling partner is not the turnover‐limiting step of the catalytic cycle. 相似文献
13.
In the presence of a catalytic amount of GaCl3, dimethyl 2‐(naphthalen‐1‐yl)cyclopropane‐1,1‐dicarboxylate 5 undergoes selective [3+2]‐annulation‐type dimerization to give a polysubstituted cyclopentane containing two naphthalenyl substituents in the vicinal position (Scheme 2). Treatment of the same cyclopropane with an equimolar amount of GaCl3?THF results in dimerization with electrophilic attack on each of the benzene rings to give [3+3] and [3+4] annulation products. The latter represent a new type of dimerization of donor? acceptor cyclopropanes. Finally, under conditions of double catalysis with GaCl3, 3,3,5,5‐tetrasubstituted 4,5‐dihydropyrazole, this cyclopropane‐dicarboxylate undergoes stereospecific dimerization as a result of electrophilic ipso‐attack to give a tetracyclic pentaleno[6a,1‐a]naphthalene derivative (Scheme 5). Possible reaction mechanisms are proposed. 相似文献
14.
Phosphine‐Initiated Domino Reaction: A Convenient Method for the Preparation of Spirocyclopentanones
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An efficient synthetic approach has been developed for the construction of the spirocyclopentanone skeleton via a phosphine‐catalyzed [3+2] annulation reaction. With this novel and economical protocol, various quaternary carbon‐centered spirocyclopentanones could be readily obtained. 相似文献
15.
《Journal of heterocyclic chemistry》2017,54(6):3377-3388
In this paper, phosphine‐catalyzed [3 + 3] annulation of Morita–Baylis–Hillman carbonates with C ,N ‐cyclic azomethine imines has been achieved. The reaction worked smoothly under mild conditions to afford 4,6,7,11b‐tetrahydro‐1H ‐pyridazino[6,1‐a ]isoquinoline derivatives in high yields with good to excellent diastereoselectivities. 相似文献
16.
A convenient and efficient synthesis of highly functionalized dihydropyrido[2,3-d]pyrimidines via a double [5 + 1] annulation strategy starting from easily available alpha-alkenoyl-alpha-carbamoyl ketene-(S,S)-acetals 1 and cheap reagents (NH4OAc, DMF, and POCl3) has been developed. In the first step of the double annulation route, 2-amino-3-carbamoyl-5,6-dihydro-4-pyridones 2 were created in high to excellent yields by a formal [5C + 1N] annulation reaction of ketene-(S,S)-acetals 1 with ammonia (from ammonium acetate). In the second step of the double annulation strategy, the highly functionalized dihydropyrido[2,3-d]pyrimidine derivatives, 7,8-dihydropyrido[2,3-d]pyrimidin-4(3H)-ones 3 (when R1 = aryl) and 7,8-dihydropyrido[2,3-d]pyrimidines 4 (when R1 = H), were constructed, respectively, in fair to good yields by reacting 2 with excessive Vilsmeier reagent (DMF/POCl3). A mechanism involved in the second [5 + 1] annulation step, including a formal [5 + 1] annulation and accompanied chlorovinylation, chloroformylation, amination, and aromatization reactions, is proposed. 相似文献
17.
Asymmetric,Three‐Component,One‐Pot Synthesis of Spiropyrazolones and 2,5‐Chromenediones from Aldol Condensation/NHC‐Catalyzed Annulation Reactions
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Dr. Lei Wang Sun Li Dr. Pankaj Chauhan Dr. Daniel Hack Arne R. Philipps Dr. Rakesh Puttreddy Prof. Dr. Kari Rissanen Prof. Dr. Gerhard Raabe Prof. Dr. Dieter Enders 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(15):5123-5127
A novel one‐pot, three‐component diastereo‐ and enantioselective synthesis of spiropyrazolones has been developed involving the aldol condensation of an enal to generate α,β‐unsaturated pyrazolones, which react with a second equivalent of enal through an N‐heterocyclic carbene (NHC)‐catalyzed [3+2] annulation. The desired spirocyclopentane pyrazolones are obtained in moderate to good yields and good to excellent stereoselectivities. Alternatively, starting from cyclic 1,3‐diketones, 2,5‐chromenediones are available through [2+4] annulation. 相似文献
18.
Rhodium(III)‐Catalyzed [3+2]/[5+2] Annulation of 4‐Aryl 1,2,3‐Triazoles with Internal Alkynes through Dual C(sp2)H Functionalization
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Yuan Yang Ming‐Bo Zhou Xuan‐Hui Ouyang Rui Pi Dr. Ren‐Jie Song Prof. Dr. Jin‐Heng Li 《Angewandte Chemie (International ed. in English)》2015,54(22):6595-6599
A rhodium(III)‐catalyzed [3+2]/[5+2] annulation of 4‐aryl 1‐tosyl‐1,2,3‐triazoles with internal alkynes is presented. This transformation provides straightforward access to indeno[1,7‐cd]azepine architectures through a sequence involving the formation of a rhodium(III) azavinyl carbene, dual C(sp2)? H functionalization, and [3+2]/[5+2] annulation. 相似文献
19.
Yuan Yang Ming‐Bo Zhou Xuan‐Hui Ouyang Rui Pi Ren‐Jie Song Jin‐Heng Li 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(22):6695-6699
A rhodium(III)‐catalyzed [3+2]/[5+2] annulation of 4‐aryl 1‐tosyl‐1,2,3‐triazoles with internal alkynes is presented. This transformation provides straightforward access to indeno[1,7‐cd]azepine architectures through a sequence involving the formation of a rhodium(III) azavinyl carbene, dual C(sp2) H functionalization, and [3+2]/[5+2] annulation. 相似文献
20.
《Tetrahedron letters》2019,60(44):151206
An effective Lewis base catalyst-controlled α-regioselective annulation reaction of γ-substituted allenoates with unsaturated pyrazolones has been developed, affording various spirocyclopentene-pyrazolones and pyrano[2,3-c]pyrazoles. The combination of PPh3 and K2CO3 promoted the [3+2] annulation to access the spirocyclopentene-pyrazolones in moderate to good yields (up to 90%) with excellent diastereoselectivities (dr >19:1), while [4+2] annulations to generate pyrano[2,3-c]pyrazoles were successfully achieved by employing DBU as catalyst (in up to 92% yield). Of importance, the asymmetric synthesis of spirocyclopentene-pyrazolone was realized by using our previously reported chiral ferrocenylphosphine catalyst. 相似文献