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1.
Philippe Guerry Philippe Blanco Heinz Brodbeck Olivier Pasteris Reinhard Neier 《Helvetica chimica acta》1991,74(1):163-178
1-Methoxycarbonyl-Substituted 2,3-Dihydropyridin-4(1H)-one(= Methyl 1,2,3,4-Tetrahydro-4-oxopyridine-1-carboxylate) as Chromophore for Photochemical [2 + 2]-Cycloadditions With olefins having an electron-acceptor as well as with olefins having an electron-donor substituent, 1-methoxycarbonyl-substituted dihydropyridinone 12 undergoes [2 + 2] cycloaddition in good preparative yields. The photochemical cycloaddition is highly regioselective. For preparative purposes, the ring junction can be equilibrated to the thermodynamically more stable cis-junction. Only the ‘endo’/‘exo’ selectivity at the C-atom bearing the olefin substituent cannot be controlled. The photodimerization of 12 is the only side reaction. Using a slight excess of the olefin, the photodimerization can be suppressed. The protecting group at the N-atom of the dihydropyridinone can be varied in order to introduce an internal sensitizer, as shown with 1-acyl-substituted compound 29 , which underwent the cycloaddition process even with sunlight. 相似文献
2.
S. S. Rynin V. I. Faustov S. E. Boganov M. P. Egorov O. M. Nefedov 《Russian Chemical Bulletin》2010,59(6):1099-1109
The cycloaddition reactions of dichlorogermylene GeCl2 to ethylene, buta-1,3-diene, and hexa-1,3,5-triene were studied within the framework of the density functional theory (PBE
and B3LYP density functionals) and by the ab initio CBS-QB3 method. The energy characteristics of the reaction of GeCl2 with ethylene were refined and non-empirical quantum chemical calculations of reaction pathways in the GeCl2 + buta-1,3-diene and GeCl2 + hexa-1,3,5-triene systems were carried out for the first time. It was shown that the [2+1] cycloaddition reactions are
kinetically hindered and thermodynamically unfavorable, while the [4+1] and [6+1] cycloaddition reactions are characterized
by low barriers and result in thermodynamically favorable products. For the [4+1] cycloaddition to buta-1,3-diene and [6+1]
cycloaddition to hexa-1,3,5-triene, the most energetically favorable reaction pathways involve a suprafacial and antarafacial
approach of reactants, respectively. 相似文献
3.
Synthesis of Cyclobutenes and Allenes by Cobalt‐Catalyzed Cross‐Dimerization of Simple Alkenes with 1,3‐Enynes
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Akira Nishimura Eri Tamai Dr. Masato Ohashi Prof. Dr. Sensuke Ogoshi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(22):6613-6617
Cobalt‐catalyzed cross‐dimerization of simple alkenes with 1,3‐enynes is reported. A [2+2] cycloaddition reaction occurred, with alkenes bearing no allylic hydrogen, by reductive elimination of a η3‐butadienyl cobaltacycle. On the other hand, aliphatic alkenes underwent 1,4‐hydroallylation by means of exo‐cyclic β‐H elimination. These reactions can provide cyclobutenes and allenes that were previously difficult to access, from simple substrates in a highly chemo‐ and regioselective manner. 相似文献
4.
Vladimir P. Zaytsev Fedor I. Zubkov Flavien A. A. Toze Daria N. Orlova Maria N. Eliseeva Dmitry G. Grudinin Eugeniya V. Nikitina Alexey V. Varlamov 《Journal of heterocyclic chemistry》2013,50(Z1):E18-E38
The interactions between 4‐R‐substituted 2‐furyl‐1,2,3,4‐tetrahydroquinolines (synthesized by the Povarov reaction) and a number of alkenes have been investigated. Maleic, dibromomaleic, dichloromaleic, and citraconic anhydrides, as well as acryloyl, methacryloyl, crotonyl, and cynnamoyl chlorides were used as alkene components. It was shown that the initial N‐acylation of the tetrahydroquinolines was followed by a spontaneous [4+2]‐cycloaddition of an N‐acryloyl substituent to the furan ring. It was established that the intramolecular Diels–Alder reaction of furans is reversible, occurs stereoselectively as exo‐addition, and led to target epoxyisoindolo[2,1‐a]tetrahydroquinolines with moderate yields. Oxidation and aromatization of the synthesized products were carried out. 相似文献
5.
Kailas K. Sanap Rama S. Kulkarni Shriniwas D. Samant 《Journal of heterocyclic chemistry》2013,50(3):713-719
The thermal [4 + 2] cycloaddition reaction of 7‐substituted 4‐styrylcoumarins with N‐phenylmaleimide and tetracyanoethylene in nitrobenzene under reflux conditions rapidly gives 3,4‐annulated coumarins as the Diels–Alder adducts. The position of the surviving double bond was determined on the basis of NMR and supported by energies of the possible structures. The effects of the 7‐substituent and the solvent on the reaction were studied. 相似文献
6.
Adrian Waldner 《Helvetica chimica acta》1989,72(7):1435-1443
[4 + 2] Cycloaddition of α, β-Unsaturated Hydrazones: Isothlazolo[4,5-b]pyridin-3(2H)-on 1,1-Dioxides (= 4-Azasaccharine Derivatives) The [4 + 2] cycloaddition of α, β -unsaturated hydrazones of type 1 (1-azabuta-1,3-dienes) with isothiazol-3(2H)-on 1,1-dioxide derivatives 10 affords, depending on the solvent used, picolinamides 15 or 17 , 4,7-dihydro-4-azasaccharine 14 or 4-azasaccharine derivatives 16 (Scheme 4). The course of the reaction is mainly influenced by the substituent R of the dienophile 10 . 相似文献
7.
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
8.
Enantioselective Formal [3+2] Cycloaddition of Epoxides with Imines under Brønsted Base Catalysis: Synthesis of 1,3‐Oxazolidines with Quaternary Stereogenic Center
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Dr. Azusa Kondoh Shiori Akahira Masafumi Oishi Prof. Dr. Masahiro Terada 《Angewandte Chemie (International ed. in English)》2018,57(21):6299-6303
The formal [3+2] cycloaddition of epoxides and unsaturated compounds is a powerful methodology for the synthesis of densely functionalized five‐membered heterocyclic compounds containing oxygen. Described is a novel enantioselective formal [3+2] cycloaddition of epoxides under Brønsted base catalysis. The bis(guanidino)iminophosphorane as a chiral organosuperbase catalyst enabled the enantioselective reaction of β,γ‐epoxysulfones with imines, owing to its strong basicity and high stereocontrolling ability, to provide enantioenriched 1,3‐oxazolidines having two stereogenic centers, including a quaternary one, in a highly diastereo‐ and enantioselective manner. 相似文献
9.
Dr. Jing Liu Dr. Yusheng Yang Weiming Shi Prof. Dr. Zhi-Xiang Yu 《Angewandte Chemie (International ed. in English)》2023,62(12):e202217654
We report here computational evidence for a metalla-Claisen rearrangement (MCR) in the case of gold-catalyzed [4+2] cycloaddition reaction of yne-dienes. The [4+2] reaction starts from exo cyclopropanation, followed by MCR and reductive elimination. The cyclopropane moiety formed in the first step is crucial for a low barrier of the MCR step. In addition, the importance of an appropriate combination of the tether group and the terminal substituent on alkyne in the yne-diene substrates was studied. The mechanism of rhodium-catalyzed [4+2] reaction of yne-dienes was also investigated to see whether an MCR mechanism is involved or not. The findings and new understanding hereby reported represent an important advance in the catalysis field. 相似文献
10.
A Novel N,P,C Cage Complex Formed by Rearrangement of a Tricyclic Phosphirane Complex: On the Importance of Non‐covalent Interactions
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Dr. Vitaly Nesterov Dr. Arturo Espinosa Dr. Gregor Schnakenburg Prof. Dr. Rainer Streubel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(23):7010-7016
The reaction of Li/Cl P‐CPh3 phosphinidenoid tungsten(0) complex 2 with dimethylcyanamide afforded tricyclic phosphirane complex 4 , an unprecedented rearrangement of which led to the novel N,P,C cage complex 6 . On the basis of DFT calculations, formation and intramolecular [3+2] cycloaddition of the transient nitrilium phosphane ylide complex 3 to a phenyl ring of the triphenylmethyl substituent to give 4 is proposed. Furthermore, theoretical evidence for terminal N‐amidinophosphinidene complex 7 , formed by [2+1] cycloelimination from 4 , is provided, and the role of the electronic structure and non‐covalent interactions of intermediate 7 discussed. 相似文献
11.
Shunsuke Suzuki Dr. Yu Shibata Prof. Dr. Ken Tanaka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(17):3698-3702
It has been established that a cationic rhodium(I)/P-phos complex catalyzes the asymmetric [2+2+2] cycloaddition of 1,6-enynes with racemic secondary allylic alcohols to produce the corresponding chiral bicyclic cyclohexenes, possessing three stereogenic centers, as a single diastereomer with excellent ee values. Mechanistic experiments revealed that the present cycloaddition proceeds through the kinetic resolution of the racemic secondary allylic alcohols, in which one enantiomer preferentially reacts with the 1,6-enyne. 相似文献
12.
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
13.
Asymmetric Brønsted Base Catalyzed and Directed [3+2] Cycloaddition of 2‐Acyl Cycloheptatrienes with Azomethine Ylides
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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
14.
A Catalytic Diastereoselective Formal [5+2] Cycloaddition Approach to Azepino[1,2‐a]indoles: Putative Donor–Acceptor Cyclobutanes as Reactive Intermediates
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Raynold Shenje M. Cynthia Martin Prof. Dr. Stefan France 《Angewandte Chemie (International ed. in English)》2014,53(50):13907-13911
A catalytic formal [5+2] cycloaddition approach to the diastereoselective synthesis of azepino[1,2‐a]indoles is reported. The reaction presumably proceeds through a Lewis acid catalyzed formal [2+2] cycloaddition of an alkene with an N‐indolyl alkylidene β‐amide ester to form a donor–acceptor cyclobutane intermediate, which subsequently undergoes an intramolecular ring‐opening cyclization. Azepine products are formed in up to 92 % yield with high degrees of diastereoselectivity (up to 34:1 d.r.). 相似文献
15.
Yu-Bo Fang Xiao-Tong Lin Prof. Dr. Guo-Shu Chen Dr. Hai Ren Dr. Dong-Sheng Deng Xiao-Wei Hu Yi-Bing Xu Dr. Shu-Jie Chen Prof. Dr. Yun-Lin Liu 《化学:亚洲杂志》2021,16(20):3086-3090
An interesting β-isoquinidine catalyzed divergent reaction was developed to produce either spirocyclopentene oxindoles, spirocyclopentadiene oxindoles or bisoxindoles in a high enantioselective fashion. The utility of this protocol was demonstrated by the versatile transformations of the products. This work not only represents the first highly stereoselective intermolecular catalytic asymmetric allylic alkylation reaction between two isatin-derived MBH carbonate molecules but also constitutes a rare example of isatin-derived MBH carbonate-based enantioselective and α-regioselective [3+2] cycloaddition reactions. 相似文献
16.
Formal Synthesis of Solanoeclepin A: Enantioselective Allene Diboration and Intramolecular [2+2] Photocycloaddition for the Construction of the Tricyclic Core
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Roel A. Kleinnijenhuis Brian J. J. Timmer Dr. Ginger Lutteke Dr. René de Gelder Prof. Dr. Jan H. van Maarseveen Prof. Dr. Henk Hiemstra 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(4):1266-1269
An enantioselective synthesis of an intermediate in the Tanino total synthesis of solanoeclepin A has been developed. The key step was an intramolecular [2+2] photocycloaddition, which led to the tricyclo[5.2.1.01, 6]decane core in six steps. The first photosubstrate, prepared through an indium‐mediated Barbier‐type reaction, gave an excellent [2+2] cycloaddition, but it could not be obtained in sufficient enantiopurity. The second photosubstrate, prepared through an asymmetric allene diborylation in high enantiomeric excess, gave the [2+2] cycloaddition product in high yield on irradiation at 365 nm on 20 g scale in a flow system. Other important steps were the replacement of a boronate group at the quaternary carbon by a vinyl group and diastereoselective cyclopropanation of an allylic alcohol. 相似文献
17.
Control of the Stereochemical Course of [4+2] Cycloaddition during trans‐Decalin Formation by Fsa2‐Family Enzymes
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Dr. Naoki Kato Dr. Toshihiko Nogawa Dr. Ryo Takita Kiyomi Kinugasa Dr. Misae Kanai Dr. Masanobu Uchiyama Dr. Hiroyuki Osada Dr. Shunji Takahashi 《Angewandte Chemie (International ed. in English)》2018,57(31):9754-9758
Enzyme‐catalyzed [4+2] cycloaddition has been proposed to be a key transformation process in various natural product biosynthetic pathways. Recently Fsa2 was found to be involved in stereospecific trans‐decalin formation during the biosynthesis of equisetin, a potent HIV‐1 integrase inhibitor. To understand the mechanisms by which fsa2 determines the stereochemistry of reaction products, we sought an fsa2 homologue that is involved in trans‐decalin formation in the biosynthetic pathway of an enantiomerically opposite analogue, and we found phm7, which is involved in the biosynthesis of phomasetin. A decalin skeleton with an unnatural configuration was successfully constructed by gene replacement of phm7 with fsa2, thus demonstrating enzymatic control of all stereochemistry in the [4+2] cycloaddition. Our findings highlight enzyme‐catalyzed [4+2] cycloaddition as a stereochemically divergent step in natural product biosynthetic pathways and open new avenues for generating derivatives with different stereochemistry. 相似文献
18.
Irreversible endo‐Selective Diels–Alder Reactions of Substituted Alkoxyfurans: A General Synthesis of endo‐Cantharimides
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Robert W. Foster Dr. Laure Benhamou Dr. Michael J. Porter Dr. Dejan‐Krešimir Bučar Prof. Helen C. Hailes Dr. Christopher J. Tame Dr. Tom D. Sheppard 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(16):6107-6114
The [4+2] cycloaddition of 3‐alkoxyfurans with N‐substituted maleimides provides the first general route for preparing endo‐cantharimides. Unlike the corresponding reaction with 3H furans, the reaction can tolerate a broad range of 2‐substitued furans including alkyl, aromatic, and heteroaromatic groups. The cycloaddition products were converted into a range of cantharimide products with promising lead‐like properties for medicinal chemistry programs. Furthermore, the electron‐rich furans are shown to react with a variety of alternative dienophiles to generate 7‐oxabicyclo[2.2.1]heptane derivatives under mild conditions. DFT calculations have been performed to rationalize the activation effect of the 3‐alkoxy group on a furan Diels–Alder reaction. 相似文献
19.
Heeyoung Lee Dahye Kang Sang Hoon Han Rina Chun Ashok Kumar Pandey Neeraj Kumar Mishra Sungwoo Hong In Su Kim 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(28):9570-9574
The ruthenium(II)‐catalyzed C?H functionalization of (hetero)aryl azomethine imines with allylic acetals is described. The initial formation of allylidene(methyl)oxoniums from allylic acetals could trigger C(sp2)?H allylation, and subsequent endo‐type [3+2] dipolar cycloaddition of polar azomethine fragments to deliver valuable indenopyrazolopyrazolones. The utility of this method is showcased by the late‐stage functionalization of bioactive molecules such as estrone and celecoxib. Combined experimental and computational investigations elucidate a plausible mechanism of this new tandem reaction. Notably, the reductive transformation of synthesized compounds into biologically relevant diazocine frameworks highlights the importance of the developed methodology. 相似文献
20.
Stereoselective [3+2] Carbocyclization of Indole‐Derived Imines and Electron‐Rich Alkenes: A Divergent Synthesis of Cyclopenta[b]indole or Tetrahydroquinoline Derivatives
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Alicia Galván Dr. Jonás Calleja Dr. Adán B. González‐Pérez Prof. Dr. Rosana Álvarez Prof. Dr. Angel R. de Lera Prof. Dr. Francisco J. Fañanás Prof. Félix Rodríguez 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(47):16769-16774
An unprecedented stereoselective [3+2] carbocyclization reaction of indole‐2‐carboxaldehydes, anilines, and electron‐rich alkenes to obtain cyclopenta[b]indoles is disclosed. This pathway is different from the well‐established Povarov reaction: the formal [4+2] cycloaddition involving the same components, which affords tetrahydroquinolines. Moreover, by simply changing the Brønsted acid catalyst, this multicomponent coupling process could be divergently directed towards the conventional Povarov pathway to produce tetrahydroquinolines or to the new pathway (anti‐Povarov) to generate cyclopenta[b]indoles. Supported by computational studies, a stepwise Mannich/Friedel–Crafts cascade is proposed for the new anti‐Povarov reaction, whereas a concerted [4+2] cycloaddition mechanism is proposed for the Povarov reaction. 相似文献