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1.
A novel, mild, robust catalyst Y(OTf)(3) for C-C bond heterolysis of N-tosyl aziridines was developed and the resulting metallo-azomethine ylides may readily undergo [3+2] dipolar cycloaddition with an electron-rich olefin via a stepwise reaction pathway with high regio- and diastereoselectivity leading to substituted pyrrolidines. 相似文献
2.
《Angewandte Chemie (International ed. in English)》2017,56(5):1351-1355
A new synthetic application of vinyl aziridines as N‐containing three‐atom components in a rhodium‐catalyzed [4+3] cycloaddition reaction is described. The reaction proceeds well with various silyl dienol ethers and vinyl aziridines, and enables the efficient synthesis of highly functionalized azepines in an enantioselective manner with net inversion of absolute configuration. The salient features of the transformation include the use of readily available substrates, high selectivity, and mild reaction conditions, as well as the versatile functionalization of the products. 相似文献
3.
Fernanda M. Ribeiro Laia 《Tetrahedron letters》2009,50(45):6180-2356
The reactivity of buta-2,3-dienoates toward aziridines is reported. Allenoates react as 2π-component in the [3+2] cycloaddition with the azomethine ylide generated from cis-1-benzyl-2-benzoyl-3-phenylaziridine affording 4-methylenepyrrolidines in a site-, regio-, and stereoselective fashion. Under conventional thermolysis, cis- and trans-2-benzoyl-1-cyclohexyl-3-phenylaziridines showed a different reactivity. These aziridines participate in formal [3+2] cycloadditions with allenes via C-N bond cleavage of the three-membered ring leading to functionalized pyrroles. 相似文献
4.
Highly Diastereo‐ and Enantioselective Palladium‐Catalyzed [3+2] Cycloaddition of Vinyl Aziridines and α,β‐Unsaturated Ketones
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Chao‐Fan Xu Bao‐Hui Zheng Jia‐Jia Suo Dr. Chang‐Hua Ding Prof. Dr. Xue‐Long Hou 《Angewandte Chemie (International ed. in English)》2015,54(5):1604-1607
A palladium‐catalyzed asymmetric [3+2] cycloaddition reaction of vinylaziridines with α,β‐unsaturated ketones, wherein the alkenes have a single activator, is realized in high diastereo‐ and enantioselectivity, thus affording 3,4‐disubstituted pyrrolidines in high yields with excellent ee values. The introduction of a methyl group at C1 of the vinyl group the vinylaziridines greatly improves the stereochemistry of the reaction. A plausible transition state is proposed. 相似文献
5.
Ryan C. Conyers Prof. Dr. Benjamin W. Gung 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(2):654-664
With the use of benzonitrile‐stabilized AuI catalyst [Au(IPr)(NCPh)]SbF6 ( Ic ; IPr=1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene), a spectrum of reactivity is observed for propargyl ester 4 a with cyclic vinyl ethers, ranging from exclusively [3C+2C] cycloaddition reactions to exclusively cyclopropanation depending only on the structure of the substrate. Some initially formed cyclopropanation products rearrange into the corresponding formally [3C+2C] cycloaddition products after treatment with fresh AuI complex at 80 °C. Vinylcyclopropanes formed from dihydrofuran and dihydropyran resisted such rearrangement, even in the presence of fresh AuI catalyst at elevated temperature. This study addresses an important mechanistic question concerning whether the five‐membered‐ring products were produced by a direct [3C+2C] cycloaddition reaction or by a sequential cyclopropanation/ring‐expansion reaction. A dual pathway is proposed for the AuI‐catalyzed reactions between propargyl esters and cyclic vinyl ethers. The different behavior among vinyl cyclic ethers is attributed to the difference in the polarization of the π bond. Highly polarized bonds appear to undergo the cycloaddition reaction whereas less polar π‐bonds produce cyclopropanes. 相似文献
6.
A cascade carbonylative ring expansion and [2+2]/[4+2] cycloaddition of strained 1-iminylphosphirane complexes with aryl allenes were reported.The carbonylative ring expansion of 1-iminylphosphirane complexes provides an azaphosphacyclohexone complex intermediate with a C=P double bond.The following [2+2] or dearomatic [4+2] cycloaddition of this intermediate with allenes is modulated by the aryl substituents on the imino carbon.The regioselective [2+2] cycloaddition with 1,1-diarylallene provides an entry to bicyclo[4.2.0]octan-4-one skeletons featuring a four-membered phosphacyclobutane moiety.While dearomatic [4+2] cycloaddition was preferred with less aromatic naphthalene and yielded octahydrochrysene skeleton containing heteroatoms. 相似文献
7.
Enantio‐ and Diastereoselective Synthesis of Chiral Allenes by Palladium‐Catalyzed Asymmetric [3+2] Cycloaddition Reactions
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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
8.
[chemical reaction: see text]. Heating a mixture of ethyl 7-iodo-2-heptynoate (or its analogues), 2-aryl aziridines, and K2CO3 in dry CH(3)CN delivers polysubstituted indolizidines. This reaction goes through an S(N)2/formal [3+2] cycloaddition process and represents the first synthetically useful example of the formal [3+2] cycloaddition process through a C-N bond cleavage of nonactivated aziridines. 相似文献
9.
Stereoselective Rhodium‐Catalysed [2+2+2] Cycloaddition of Linear Allene–Ene/Yne–Allene Substrates: Reactivity and Theoretical Mechanistic Studies
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Ewelina Haraburda Òscar Torres Dr. Teodor Parella Prof. Dr. Miquel Solà Dr. Anna Pla‐Quintana 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(17):5034-5045
Allene–ene–allene ( 2 and 5 ) and allene–yne–allene ( 3 and 7 ) N‐tosyl and O‐linked substrates were satisfactorily synthesised. The [2+2+2] cycloaddition reaction catalysed by the Wilkinson catalyst [RhCl(PPh3)3] was evaluated. Substrates 2 and 5 , which bear a double bond in the central position, gave a tricyclic structure in a reaction in which four contiguous stereogenic centres were formed as a single diastereomer. The reaction of substrates 3 and 7 , which bear a triple bond in the central position, gave a tricyclic structure with a cyclohexenic ring core, again in a diastereoselective manner. All cycloadducts were formed by a regioselective reaction of the inner allene double bond and, therefore, feature an exocyclic diene motif. A Diels–Alder reaction on N‐tosyl linked cycloadducts 8 and 10 allowed pentacyclic scaffolds to be diastereoselectively constructed. The reactivity of the allenes on [2+2+2] cycloaddition reactions was studied for the first time by density functional theory calculations. This mechanistic study rationalizes the order in which the unsaturations take part in the catalytic cycle, the reactivity of the two double bonds of the allene towards the [2+2+2] cycloaddition reaction, and the diastereoselectivity of the reaction. 相似文献
10.
Microwave irradiation of alkynyl allenes affords an intramolecular [2 + 2] cycloaddition reaction. This cycloaddition provides an efficient route to bicyclomethylenecyclobutenes. The reaction occurs with complete regioselectivity for the distal double bond of the allene for the selective formation of a variety of hetero- and carbocyclic substrates. Bicyclo[4.2.0]octadienes and bicyclo[5.2.0]nonadienes have been prepared in high yield. [reaction: see text] 相似文献
11.
In this report, the dipolarophile imines with easily removable activating group O,O-diethyl(thio)phosphoryl have been investigated in the nucleophilic phosphine-catalyzed [3+2] cycloaddition reaction of electron-deficient allenes. Under the catalysis of a tertiary phosphine, N-(thio)phosphorylimines readily undergo the [3+2] cycloaddition reaction with ethyl 2,3-butadienoate or ethyl 2,3-pentadienoate, affording the corresponding N-(thio)phosphoryl 3-pyrrolines in moderate to high yields with good diastereoselectivity. Removal of the (thio)phosphoryl group from the adducts has been successfully achieved via the acidic methanolysis of the P-N bond, giving the free amine 3-pyrrolines in fair to good yields without severe aromatization. Thus, a facile synthesis of N-unsubstituted 3-pyrrolines is established from the phosphine-catalyzed [3+2] cycloaddition reaction of allenes with imines. 相似文献
12.
Efficient and Selective Formation of Unsaturated Carboxylic and Phenylacetic Acids from Diketene
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Takamichi Mori Yusuke Akioka Hisaho Kawahara Ryo Ninokata Dr. Gen Onodera Prof. Dr. Masanari Kimura 《Angewandte Chemie (International ed. in English)》2014,53(39):10434-10438
A nickel catalyst promotes the multicomponent coupling reaction of diketene, an alkyne, and Me2Zn to provide 3‐methylene‐4‐hexenoic acids in excellent yields. Under similar conditions, the combination of the nickel catalyst and Et2Al(OEt) promotes a cycloaddition reaction involving dimerization of an alkyne to furnish phenylacetic acids. In the presence of PPh3, a formal [2+2+1+1] cycloaddition reaction proceeds to afford regioisomeric phenylacetic acids via cleavage of the C?C bond. 相似文献
13.
Modular Access to the Stereoisomers of Fused Bicyclic Azepines: Rhodium‐Catalyzed Intramolecular Stereospecific Hetero‐[5+2] Cycloaddition of Vinyl Aziridines and Alkenes
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Dr. Jian‐Jun Feng Tao‐Yan Lin Prof. Dr. Hai‐Hong Wu Prof. Dr. Junliang Zhang 《Angewandte Chemie (International ed. in English)》2015,54(52):15854-15858
The first rhodium‐catalyzed intramolecular hetero‐[5+2] cycloaddition reaction of vinyl aziridines and alkenes was realized, wherein both internal and terminal alkenes were applicable. With this method, a variety of unique substituted chiral fused bicyclic azepines, bearing multiple contiguous stereogenic centers, were facilely accessed in a straightforward, high‐yielding, and highly stereoselective manner under mild reaction conditions. Notably, the E/Z geometry of the C?C bonds in the vinyl aziridine‐alkene substrates impact the cis/trans stereochemistry of the cycloadducts and up to six stereoisomers could be delivered. 相似文献
14.
Ohno H Mizutani T Kadoh Y Aso A Miyamura K Fujii N Tanaka T 《The Journal of organic chemistry》2007,72(12):4378-4389
Thermal [2 + 2] cycloaddition of allenes with an additional multiple bond is described. By simply heating the allenenes or allenynes having a three-atom tether in an appropriate solvent such as dioxane or DMF, the distal double bond of the allenic moiety regioselectively participates in the cycloaddition to form bicyclo[4.2.0]oct-5-ene derivatives in good to excellent yields. In all the reactions of allenenes, the olefin geometry was completely transferred to the cycloadducts. While the reaction of terminal allenes afforded bicyclic cyclobutane derivatives as a single isomer, the cycloaddition of some internal allenes with axial chirality yielded a diastereomeric mixture of cycloadducts. These results are in good accordance with the stepwise mechanism through a biradical intermediate with a coplanar allyl radical. 相似文献
15.
Fernanda M. Ribeiro Laia Ana Matos Beja Teresa M.V.D. Pinho e Melo 《Tetrahedron》2010,66(46):8815-8822
The reactivity of buta-2,3-dienoates towards aziridines is reported. Typically, allenoates react as the 2π-component in the [3+2] cycloaddition with azomethine ylides generated from aziridines, affording 4-methylenepyrrolidines in a site-, regio- and stereoselective fashion. However, N-cyclohexyl- or N-tert-butyl-2-benzoyl-3-phenylaziridines showed a different reactivity in the reaction with buta-2,3-dienoates. Pyrrole derivatives were obtained as single or major products resulting from a formal [3+2] cycloaddition via C-N bond cleavage of the three-membered ring heterocycle leading to functionalized pyrroles. From the reaction with allenoates bearing bulkier C-4 substituents 4-methylenepyrrolidines were also formed as minor products. 相似文献
16.
《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
17.
Kazuta Ito Yoshihiro Hara Seiji Mori Prof. Dr. Hiroyuki Kusama Dr. Nobuharu Iwasawa Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(45):12408-12416
The [3+2] cycloaddition reaction of a tungsten‐containing carbonyl ylide with methyl vinyl ether and the insertion reactions of the nonstabilized carbene complex intermediates produced have been investigated through the use of B3LYP density functional theory. The [3+2] cycloaddition reaction of the tungsten‐containing carbonyl ylide has been proven to proceed concertedly, reversibly, and with high endo selectivity. The intermolecular Si? H insertion reactions of the carbene complex intermediates have been proven to be favored over the intramolecular C? H insertion, in good agreement with experimental results. Moreover, the kinetic endo/exo ratio of the [3+2] cycloaddition reaction has been shown to determine the endo/exo selectivity of the Si? H insertion products. In addition, secondary orbital interactions involving the benzene ring and the carbonyl ligand on the metal center have turned out to strongly influence the high endo selectivity of the [3+2] cycloaddition reaction with methyl vinyl ether. 相似文献
18.
This paper describes a novel route to functionalized piperidines via a formal [3+3] cycloaddition reaction of activated aziridines and palladium-trimethylenemethane (Pd-TMM) complexes. The cycloaddition reaction generally proceeds enantiospecifically with ring opening at the least hindered site of the aziridine. Therefore, readily available enantiomerically pure 2-substituted aziridines can be utilized to prepare enantiomerically pure 2-substituted piperidines in good to excellent yield. The N-substituent on the aziridine proved to be crucial to the success of this reaction with only 4-toluenesulfonyl (Ts) and 4-methoxybenzenesulfonyl (PMBS) aziridines permitting smooth cycloaddition to take place. Additionally, spirocyclic aziridines have been found to participate in the [3+3] cycloaddition reaction, whereas 2,3-disubstituted aziridines can be applied to provide fused bicyclic piperidines, albeit in low yield. 相似文献
19.
Wei Ding Naohiko Yoshikai 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(8):2522-2526
An intermolecular [2+2] cycloaddition reaction between an alkyne and an allene is reported. In the presence of a cobalt(I)/diphosphine catalyst, a near equimolar mixture of the alkyne and allene is converted into a 3‐alkylidenecyclobutene derivative in good yield with high regioselectivity. The reaction tolerates a variety of internal alkynes and mono‐ or disubstituted allenes bearing various functional groups. The reaction is proposed to involve regioselective oxidative cyclization of the alkyne and allene to form a 4‐alkylidenecobaltacyclopentene intermediate, with subsequent C?C reductive elimination. 相似文献
20.
Aromatic Amide‐Derived Non‐Biaryl Atropisomers as Highly Efficient Ligands in Silver‐Catalyzed Asymmetric Cycloaddition Reactions
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Xing‐Feng Bai Tao Song Dr. Zheng Xu Prof. Chun‐Gu Xia Wei‐Sheng Huang Prof. Dr. Li‐Wen Xu 《Angewandte Chemie (International ed. in English)》2015,54(17):5255-5259
The synthesis of a series of aromatic amide‐derived non‐biaryl atropisomers with a phosphine group and multiple stereogenic centers is reported. The novel phosphine ligands exhibit high diastereo‐ and enantioselectivities (up to >99:1 d.r., 95–99 % ee) as well as yields in the silver‐catalyzed asymmetric [3+2] cycloaddition of aldiminoesters with nitroalkenes, which provides a highly enantioselective strategy for the synthesis of optically pure nitro‐substituted pyrrolidines. In addition, the experimental results with regard to the carbon stereogenic center as well as the amide stereochemistry confirmed the potential of hemilabile atropisomers as chiral ligand in catalytic asymmetric [3+2] cycloaddition reaction. 相似文献