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Journal articles on the topic '[4+2] cycloaddition reaction'

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Published: 4 June 2021

Last updated: 1 February 2022

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1

Grygorenko, Oleksandr O., Viktoriia S. Moskvina, Oleksandr V. Hryshchuk, and Andriy V. Tymtsunik. "Cycloadditions of Alkenylboronic Derivatives." Synthesis 52, no. 19 (2020): 2761–80. http://dx.doi.org/10.1055/s-0040-1707159.

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The literature on cycloaddition reactions of boron-containing alkenes is surveyed with 132 references. The data are categorized according to the reaction type ([2+1], [2+2], [3+2], [4+2], and [4+3] cycloadditions). The cyclopropanation and the Diels–Alder reactions of alkenylboronic derivatives have been studied more or less comprehensively, and for some substrates, they can be considered as convenient methods for the rapid regio- and stereoselective construction of even complex cyclic systems. Other types of the cycloadditions, as well as mechanistic aspects of the processes, have been addres

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2

Winne, Johan, Jan Hullaert, Bram Denoo, Mien Christiaens, and Brenda Callebaut. "Heterocycles as Moderators of Allyl Cation Cycloaddition Reactivity." Synlett 28, no. 18 (2017): 2345–52. http://dx.doi.org/10.1055/s-0036-1588511.

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For the rapid elaboration of polycarbocyclic scaffolds, prevalent in many important families of terpenoid natural products, allyl cations derived from simple heterocyclic alcohols can be used as versatile reaction partners in both (4+3) and (3+2) cycloaddition pathways. Our recent progress in this area is outlined, pointing towards the untapped potential of heterocycles to act as reagents in novel or known but challenging organic transformations.1 Heterocyclic Reagents2 Cycloadditions and Allyl Cations3 Furfuryl Cations in Cycloadditions4 Heterocycle-Substituted Cations in Cycloadditions5 Mech

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3

Harmata, Michael, and Aswin Garimalla. "Derivatives of Alkyl 2-Hydroxy-3-oxocyclopent-1-enecarboxylates and Intermolecular [4+2] Cycloadditions of Cyclopentadienones Prepared Therefrom." Synthesis 50, no. 22 (2018): 4483–89. http://dx.doi.org/10.1055/s-0037-1610184.

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Some derivatives of alkyl 2-hydroxy-3-oxocyclopent-1-enecarboxylates have been synthesized and their reactivity as progenitors of cyclopentadienones for intermolecular [4+2]-cycloaddition reactions has been evaluated. It was found that the derivative containing a phosphate ester leaving group gave better yields in the cycloaddition reaction among the derivatives studied. The yields of the cycloaddition reactions were moderate, perhaps due side reactions not leading to the reactive intermediate cyclopentadienone.

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4

Newton, Rebecca, and G. Paul Savage. "Regioselective 1,3-Dipolar Cycloaddition Reactions of 4-Methylene-2-oxazolidinones with Benzonitrile Oxide." Australian Journal of Chemistry 61, no. 6 (2008): 432. http://dx.doi.org/10.1071/ch08111.

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Substituted 4-methylene-2-oxazolidinones were prepared in two steps by cyclizing O-propargyl carbamates, which in turn were prepared from propargyl alcohols and phenyl isocyanate. The 4-methylene-2-oxazolidinones underwent a 1,3-dipolar cycloaddition reaction with benzonitrile oxide to give the corresponding spiro heterocycles. Where the substitution pattern on the oxazolidinone engendered facial asymmetry, the cycloadditon reaction proceeded with 5:1 selectivity for the less hindered face of the dipolarophile.

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5

Burger, Klaus, Eva Höß, Norbert Sewald, Klaus Geith, Jürgen Riede, and Peter Bissinger. "Zum Cycloadditionsverhalten von 5-Azido-4-trifluormethyl-1,3-azolen / Cycloaddition Reactions with 5-Azido-4-trifluoromethyl-1,3-azoles." Zeitschrift für Naturforschung B 45, no. 12 (1990): 1695–708. http://dx.doi.org/10.1515/znb-1990-1217.

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[3+2] Cycloaddition reactions of 5-azido-4-trifluoromethyl-1,3-azoles with various CC multiple bond systems are described. On reaction of 5-azido-4-trifluoromethylthiazoles 2 with 2,3-dimethylbuta-1,3-diene no [3+2] cycloaddition products could be isolated, 5,6-dihydro-2 H-pyrane 19 was formed exclusively. Photolysis of 1,2,3-triazoles 23, 24, obtained from 2 and electron deficient alkynes, yields imidazo[5,1-b]thiazoles 28. This photoreaction can be interpreted mechanistically as a “Thio-Cornforth-Reaction”.

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6

Li, Jian, Shangrong Zhu, Qiuneng Xu, Li Liu, and Shenghu Yan. "Brønsted acid mediated intramolecular cyclopropane ring expansion/[4 + 2]-cycloaddition." Organic & Biomolecular Chemistry 17, no. 47 (2019): 10004–8. http://dx.doi.org/10.1039/c9ob02379h.

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A cascade reaction of 3-hydroxy-2-phenylisoindolin-1-one and cyclopropyl ketone has been developed via BrØnsted acid-promoted ring-opening/intramolecular cross-cycloaddition/[4 + 2]-cycloaddition process.

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7

Wiberg, N., G. Preiner, G. Wagner, and H. Köpf. "Reaktivität des labilen, durch Adduktbildung mit Ph2C=NSiMe3 gespeicherten Silaethens Me2Si=C(SiMe3)2 / Reactivity of the Labile Silaethene Me2Si = C(SiMe3)2, Stored as Ph2C =NSiMe3 Adducts." Zeitschrift für Naturforschung B 42, no. 9 (1987): 1062–74. http://dx.doi.org/10.1515/znb-1987-0902.

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Silaethene Me2Si = C(SiMe3)2 (1), stored as Ph2C=NSiMe3 adducts and regenerated from the adducts at about 100 °C as a reaction intermediate, combines with reactants a-b (e. g. HO-H, RO-H. RCOO-H, RS-H. RHN-H, Ph2CN-H, RO-SiR3, R2N-SiR3, Ph2CN-SiR3, Cl-GeR3, Cl-SnR3) with insertion into the a-b bond, with a=b (e.g. 0 = CPh2, Me3SiN = CPh2, CH2=CHOMe, cis-piperylene), a=b=c (e.g. RN = N = N, O = N=N). a=b-c=d (e.g. butadiene, isoprene, trans-piperylene, 2,3-dimethylbutadiene, cyclopentadiene, anthracene, benzophenone, N-trimethylsilylbenzophenoneimine) under [2+2]-, [2+3]- as well as [2+A]-cyclo

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8

Choi, Cheol Ho, and Mark S. Gordon. "Cycloaddition Reactions of Dienes on the SI(100)-2 × 1 Surface." International Journal of Modern Physics B 17, no. 08n09 (2003): 1205–10. http://dx.doi.org/10.1142/s0217979203018752.

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Quantum mechanical methods were adopted to study the surface reaction mechanisms of 1, 3-cyclohexadiene and acrylonitrile on the Si(100)-2x1 surface. According to the computed potential energy surfaces, both ⌊4+2⌋ and ⌊2+2⌋ cycloaddition products resulting from the reactions of surface dimers are possible due to the negligible activation barriers at the surface. Isomerization reactions among the surface products are very unlikely due to the predicted large activation barriers preventing thermal redistributions of the surface products. As a result, the distribution of the final surface products

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9

Kitagaki, Shinji, Yuki Okumura, and Chisato Mukai. "Reaction of ene-bis(phosphinylallenes): [2+2] versus [4+2] cycloaddition." Tetrahedron 62, no. 44 (2006): 10311–20. http://dx.doi.org/10.1016/j.tet.2006.08.083.

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10

Wu, Di, Rakesh Ganguly, Yongxin Li, Sin Ni Hoo, Hajime Hirao, and Rei Kinjo. "Reversible [4 + 2] cycloaddition reaction of 1,3,2,5-diazadiborinine with ethylene." Chemical Science 6, no. 12 (2015): 7150–55. http://dx.doi.org/10.1039/c5sc03174e.

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11

Ryan, Sarah J., Craig L. Francis, and G. Paul Savage. "Benzonitrile Oxide Cycloadditions with Exocyclic Methylene Benzothiazepine Dioxides." Australian Journal of Chemistry 67, no. 3 (2014): 381. http://dx.doi.org/10.1071/ch13444.

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N-substituted 5-methylene-2,3,4,5-tetrahydrobenzo[f][1,2]thiazepine 1,1-dioxides underwent 1,3-dipolar cycloaddition with benzonitrile oxide, generated in situ, to give isoxazoline spiro adducts. The cycloadditions were completely regioselective to give the hitherto unreported 3,4-dihydro-2H,4′H-spiro[benzo[f][1,2]thiazepine-5,5′-isoxazole] 1,1-dioxide cycloadduct. Where the N-substituent on the sulfonamide cycloaddition precursor was a 2-substituted arene, the resulting atropisomerism along the N-aryl bond led to facial selectivity in the cycloaddition reaction, with greater than 90 % diaster

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12

Tsui, Jordan A., Timothy M. Bolton, and Brian T. Sterenberg. "Tungsten coordination chemistry of 1,4-bisdiphenylphosphinobutadiyne — Synthesis of coordination macrocycles and factors controlling diyne cycloaddition." Canadian Journal of Chemistry 87, no. 1 (2009): 197–204. http://dx.doi.org/10.1139/v08-123.

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The 1:1 reaction of [W(CO)4(2-picoline)2] (1) with Ph2PCtriple bondC-Ctriple bondCPPh2 (2) led to {[cis-W(CO)4]2(µ-Ph2PC4PPh2)2} (3), in which two bis(diphenylphosphino)butadiyne ligands bridge two tetracarbonyltungsten centres. Reaction of 1 with excess 2 led to [cis-W(CO)4(Ph2PC4PPh2-κ1-P)2] (4), in which two dangling bis-phosphines are coordinated to one metal centre, and reaction of 2 with two equivalents of 1 led to {[W(2-picoline)(CO)4]2(µ-Ph2PC4PPh2)} (5), in which one ligand bridges two tungsten centres. Combination of 4 and 5 led to the trimeric complex {[cis-W(CO)4]3(µ-Ph2PC4PPh2)3}

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13

Leblanc, Yves, Brian J. Fitzsimmons, James P. Springer, and Joshua Rokach. "[4 + 2] Cycloaddition reaction of dibenzyl azodicarboxylate and glycals." Journal of the American Chemical Society 111, no. 8 (1989): 2995–3000. http://dx.doi.org/10.1021/ja00190a037.

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14

Kametani, Tetsuji, Hajime Takeda, Yukio Suzuki, and Toshio Honda. "Synthesis of Quinoline Derivatives by [4+2]Cycloaddition Reaction." Synthetic Communications 15, no. 6 (1985): 499–505. http://dx.doi.org/10.1080/00397918508063833.

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15

Korenchenko, O. V., A. Yu Aksinenko, V. B. Sokolov, A. N. Pushin, and I. V. Martynov. "Alkoxycarbonylimines of hexafluoroacetone in reaction of [2+4]-cycloaddition." Russian Chemical Bulletin 44, no. 9 (1995): 1740–44. http://dx.doi.org/10.1007/bf01151302.

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16

Teitei, T. "The Synthesis of (3'-Oxo-3',4'-Dihydro-2'h-1',4'-Benzothiazin-2'-Yl)Acetic Acid and (3'-Oxo-3',4'-Dihydro-2'h-1',4'-Benzoxazin-2'-Yl)Acetic Acid-Derivatives." Australian Journal of Chemistry 39, no. 3 (1986): 503. http://dx.doi.org/10.1071/ch9860503.

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Reaction of o-aminophenol with various maleic anhydrides gave first 2-hydroxymaleanilic acids (4-(2′-hydroxyphenylamino)-4-oxobut-2-enoic acids) (1), which were then converted into the 3-oxo-1,4-benzoxazines (2d-h) and (3f-1) under mild basic conditions; similarly the reaction of o- aminothiophenol with the maleic anhydrides gave the 3-oxo-1,4-benzothiazines (2a), (3a) and (3d) in one step. The facile cycloaddition and esterification of 2-hydroxymaleanilic acids to form the benzoxazines observed in this work is discussed in terms of the formation of the isomaleimide type intermediate (7).

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17

Jasiński, Radomir, Michał Rzyman, and Andrzej Barański. "Conjugated nitroalkenes in cycloaddition reactions. Part 2. Diels–Alder reactions of E-2-aryl-1-cyano-1-nitroethenes with cyclopentadiene." Collection of Czechoslovak Chemical Communications 75, no. 9 (2010): 919–29. http://dx.doi.org/10.1135/cccc2009562.

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The reaction between E-2-aryl-1-cyano-1-nitroethenes 1a–1e and cyclopentadiene (2) occurs according to the carbodiene [4+2]cycloaddition scheme and leads to the corresponding 6-endo-aryl-5-endo-cyano-5-exo-nitronorbornenes 3a–3e and 6-exo-aryl-5-exo-cyano-5-endo-nitronorbornenes 4a–4e as the only reaction products. The attempts to detect the products of heterodiene [4+2]cycloaddition in the reaction environment were not successful.

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18

Guranova, Natalia, Pavel Golubev, Olga Bakulina, Dmitry Dar'in, Grigory Kantin, and Mikhail Krasavin. "Unexpected formal [4 + 2]-cycloaddition of chalcone imines and homophthalic anhydrides: preparation of dihydropyridin-2(1H)-ones." Organic & Biomolecular Chemistry 19, no. 17 (2021): 3829–33. http://dx.doi.org/10.1039/d1ob00534k.

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Chalcone imines were reacted with homophthalic anhydrides to serve as a four-atom building block in a [4+2]-formal cycloaddition reaction with unexpected chemoselectivity (Castagnoli–Cushman-type reaction), providing dihydropyridin-2(1H)-ones.

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19

Hegab, Mohamed I., Abd El-Galil A. Amr та Farouk M. E. Abdel-Megeid. "[4 + 2]-Cycloaddition Reactions Involving α-Oxo Thioketone Intermediates". Zeitschrift für Naturforschung B 57, № 8 (2002): 922–27. http://dx.doi.org/10.1515/znb-2002-0813.

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α-Chloro β-oxo sulfenyl chlorides 2 were reduced by iodide ions to the corresponding α-oxo thioketones 3 which dimerized in situ in a hetero-[4 + 2] cycloaddition to give the 1,3,4- oxadithiin derivatives 4. The α-oxo thioketones 3, in situ, cyclized also with 2,3-dimethyl-1,3- butadiene to give the corresponding adducts 5 and only in case of the oxo thioketone intermediate 3d two products 4d and 5d were obtained. Also, The α-oxo thioketones 3a,c, underwent in situ, cycloaddition with furan to give the corresponding adducts 6a,c together with the corresponding thioketone dimers 4a,c. When this

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20

Ishihara, K., and A. Sakakura. "ChemInform Abstract: [4+2]-Cycloaddition Reactions." ChemInform 42, no. 42 (2011): no. http://dx.doi.org/10.1002/chin.201142259.

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21

Vollbrecht, Susanne, Uwe Klingebiel, and Dieter Schmidt-Bäse. "Additionen an die Si=N-Doppelbindung – Kristallstruktur eines (SiNCO)-Vierringes / Additions to the Si=N-Double Bond - Crystal Structure of a (SiNCO)-Four Membered Ring." Zeitschrift für Naturforschung B 46, no. 6 (1991): 709–13. http://dx.doi.org/10.1515/znb-1991-0603.

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In the reaction with benzophenone and phenylaldehyde lithiated aminofluorosilanes behave like iminosilanes. Four membered rings are formed in (2+2) cycloadditions. The oxaazasilacyclobutane ((CMe3)2Si—NCMe3—C6H5CH—O—) was purified by destillation. Single crystals were obtained by recrystallization from hexane. The thermal cleavage of the (SiNCO)-rings leads to carboimines and cyclosiloxanes. The lithium derivate of di-tert-butylfluorosilyl-2.6-diisopropylphenylamine reacts with 2-methyl-propenal-2 in two competing ways. In a (2+4) cycloaddition an 1-oxa-3-aza-2-sila-5-cyclohexene is formed, an

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22

Sleziak, Róbert, and Alžbeta Krutošíková. "Cycloaddition Reactions of Furo[2,3-b]pyrroles." Collection of Czechoslovak Chemical Communications 64, no. 2 (1999): 321–28. http://dx.doi.org/10.1135/cccc19990321.

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Reactions of furo[2,3-b]pyrroles with dimethyl butynedioate and ethyl propynoate were investigated. The reaction course is influenced by the substituents on the fused system. Products of [4+2]cycloaddition to the furan ring leading to indole derivatives have been observed. In the case of the reaction of methyl 6H-furo[2,3-b]pyrrole-5-carboxylate (1a) with dimethyl butynedioate, products of [4+2]cycloaddition to the furan ring as well as of Michael addition to the pyrrole ring leading to N-substituted indole derivative 3 have been observed.

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23

Fazylov, S. D., O. A. Nurkenov, A. E. Arinova, et al. "SYNTHESIS OF PROPERTIES N-METHYL-2-(PYRID-4-YL)-3,4-FULLEROPYRROLIDINE." SERIES CHEMISTRY AND TECHNOLOGY 2, no. 440 (2020): 62–68. http://dx.doi.org/10.32014/2020.2518-1491.24.

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The article is devoted to the reactions of [2+3] cycloaddition of pyridine-4-aldehyde to fullerene C60, as well as to the preparation of its water-soluble from of the resulting reaction product N-methyl-2-(pyrid-4-yl)-3,4-fulleropyrrolidine. A literature review of organic compounds containing the pyrrolidine cycle was carried out. It is noted that such compounds have a wide spectrum of biological activity and are part of many drugs of both natural and synthetic origin. In this regard, an interesting “pharmacophore” group is the pyridine cycle, which is part of about 5% of all known drugs. The

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24

Seitz, Gunther, and Johanna Siegl. "Synthese neuer Pyridin-C-nukleoside der 2 ,3 -Didesoxyribose durch „inverse“ [4+2]-Cycloaddition Synthesis of Novel Pyridine-C-nucleosides of 2,3-Dideoxyribose by „Inverse“ [4+2]-Cycloaddition." Zeitschrift für Naturforschung B 52, no. 7 (1997): 851–58. http://dx.doi.org/10.1515/znb-1997-0715.

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The anomeric imido esters 5 and 6, appropriate precursors for C-nucleoside synthesis, were prepared and utilized as heterodienophiles in a Diels-Alder reaction with inverse electron demand to yield the novel, protected 1.2.4-triazine C-nucleosides 8 and 9. They could be deprotected by treatment with 70% trifluoroacetic acid to furnish the free C-nucleosides 10 and 11. The triazine „aglycon“ of 8 contains an electron deficient diazadiene system, highly activated to react with various electron rich dienophiles such as enamines, enol ethers and several cyclic ketene acetals in an „inverse“ [4+2]-

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25

Harmata, Michael, and Darin E. Jones. "Heteroatom-stabilized allylic cations in 4+3 cycloadditions. A tandem Peterson olefination/4+3 cycloaddition reaction." Tetrahedron Letters 38, no. 22 (1997): 3861–62. http://dx.doi.org/10.1016/s0040-4039(97)00775-2.

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26

Zawadzińska, Karolina, та Karolina Kula. "Application of β-Phosphorylated Nitroethenes in [3+2] Cycloaddition Reactions Involving Benzonitrile N-Oxide in the Light of a DFT Computational Study". Organics 2, № 1 (2021): 26–37. http://dx.doi.org/10.3390/org2010003.

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The regiochemistry of [3+2] cycloaddition (32CA) processes between benzonitrile N-oxide 1 and β-phosphorylated analogues of nitroethenes 2a–c has been studied using the Density Functional Theory (DFT) at the M062X/6-31+G(d) theory level. The obtained results of reactivity indices show that benzonitrile N-oxide 1 can be classified both as a moderate electrophile and moderate nucleophile, while β-phosphorylated analogues of nitroethenes 2a–c can be classified as strong electrophiles and marginal nucleophiles. Moreover, the analysis of CDFT shows that for [3+2] cycloadditions with the participati

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27

Lin, Chao, Hong-Jin Du, Hui Zhao, et al. "A formal intermolecular [4 + 2] cycloaddition reaction of 1,3-disubstituted indoles and alkylquinones." Organic & Biomolecular Chemistry 15, no. 16 (2017): 3472–78. http://dx.doi.org/10.1039/c7ob00392g.

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28

Mohammad-Salim, Haydar A., and Hassan H. Abdallah. "Theoretical Study of the [4+2] Cycloaddition Reaction of Trifluoroethylene with Five-membered Chalcogens Heterocyclic Compounds." ARO-THE SCIENTIFIC JOURNAL OF KOYA UNIVERSITY 7, no. 2 (2019): 69–77. http://dx.doi.org/10.14500/aro.10575.

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[4+2] cycloaddition reaction has enormous significant in organic chemistry synthesis reactions and yet remains unexplored for the synthesis of fluorine-containing compounds. A density functional theory study of the stereo- and regioselectivity of the [4+2] cycloaddition reaction of trifluoroethylene with furan, thiophene, and selenophene was carried out in the gas phase. The B3LYP functional is used throughout in combination with 6-31G(d) basis set. The analysis of stationary points and the energetic parameters indicates that the reaction mechanism is concerted and confirms that the exo-adduct

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29

Cambie, RC, PI Higgs, PS Rutledge, and PD Woodgate. "Annulations of Podocarpic Acid Derivatives via an Aryne Intermediate." Australian Journal of Chemistry 47, no. 10 (1994): 1815. http://dx.doi.org/10.1071/ch9941815.

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The cycloaddition of substituted furans to the diterpenoid aryne (39), generated by in situ diazotization of the anthranilic acid (1) followed by cleavage of the annulated 1,4- epoxydecahydrochrysenes, provides a convenient method for the preparation in high yield of the previously unknown 1-substituted octahydrochrysen-4-ols. Use of 1,3-dipoles under the same procedure, or under a modified procedure involving pre-isolation of the diazonium tetrafluoroborate salt (9), gave novel annulated heterocyclic products directly. Attempted [2+2] cycloadditions of electron-rich alkenes to the diterpenoid

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30

Korchowiec, Jacek. "Importance of charge-transfer effects in [4+2] cycloaddition reaction." Journal of Molecular Structure: THEOCHEM 663, no. 1-3 (2003): 175–85. http://dx.doi.org/10.1016/j.theochem.2003.08.125.

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31

VALEEV, F. A., I. N. GAISINA, and M. S. MIFTAKHOV. "ChemInform Abstract: (4 + 2) Cycloaddition Reaction of Levoglucosenone with Piperylene." ChemInform 28, no. 16 (2010): no. http://dx.doi.org/10.1002/chin.199716235.

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32

Liu, Bin, Huijuan Wang, Hujun Xie, et al. "Osmapyridine and Osmapyridinium from a Formal [4+2] Cycloaddition Reaction." Angewandte Chemie International Edition 48, no. 30 (2009): 5430–34. http://dx.doi.org/10.1002/anie.200900998.

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33

Liu, Bin, Huijuan Wang, Hujun Xie, et al. "Osmapyridine and Osmapyridinium from a Formal [4+2] Cycloaddition Reaction." Angewandte Chemie 121, no. 30 (2009): 5538–42. http://dx.doi.org/10.1002/ange.200900998.

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34

Li, Chengjie, Jie Zhang, Xiujun Liu, et al. "Synthesis of corrole–fullerene dyads via [4 + 2] cycloaddition reaction." RSC Adv. 4, no. 77 (2014): 40758–62. http://dx.doi.org/10.1039/c4ra07204a.

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Corrole–fullerene dyads were prepared by treating anthracene-functionalized corroles with fullerene. Photo physical study indicated that the excited corrole unit was quenched due to the introduction of fullerene.

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35

Chernov, N. M., T. V. Moroz, R. V. Shutov, et al. "Synthesis of New 4,4a-Dihydroxanthones via [4+2]-Cycloaddition Reaction." Russian Journal of General Chemistry 89, no. 12 (2019): 2463–70. http://dx.doi.org/10.1134/s1070363219120223.

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36

Valeev, F. A., I. N. Gaisina, and M. S. Miftakhov. "On the [4+2]-cycloaddition reaction of levoglucosenone with piperylene." Russian Chemical Bulletin 45, no. 10 (1996): 2453–55. http://dx.doi.org/10.1007/bf01435403.

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37

Lin, Cheng-Tung, and Wen-Jei Hsu. "Study of trichloronitrosomethane: regioselective cycloadditions of 2-substituted-1,3-butadienes." Canadian Journal of Chemistry 67, no. 12 (1989): 2153–61. http://dx.doi.org/10.1139/v89-335.

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The regioselectivity of cycloaddition reactions of trichloronitrosomethane (1) with 2-alkyl (R = Me, Et, i-Pr, t-Bu, CF3, Bz, and Cl) and 2-aryl (Ar = Ph, 4-CH3OPh, 4-CH3Ph, 3-CH3Ph, and 4-ClPh) 1,3-butadienes is described. The orientation of cycloaddition is substituent dependent, producing 2,5-disubstituted (para) and 2,4-disubstituted (meta) 3,6-dihydro-1,2-oxazines from 2-alkyl- and 2-aryl-1,3-butadienes respectively. Increasing the bulk of the substituent from methyl to tert-butyl in 2-alkyl-1,3-butadienes increases the regioselectivity. Kinetic studies in various solvents indicate that p

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38

Hunnur, Raveendra K., Prashant R. Latthe, and Bharati V. Badami. "1,3-Dipolar Cycloaddition Reactions in Heterocyclic Synthesis. Synthesis of [1-[4-(thiazolyl/imidazothiazolyl/triazolyl)phenyl]-1H-pyrazole-3,4-dicarboxylate esters from 3-(4-acetylphenyl)sydnone." Journal of Chemical Research 2005, no. 9 (2005): 592–94. http://dx.doi.org/10.3184/030823405774308907.

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Cycloaddition of 3-(4-acetylphenyl)sydnone (1) with DMAD gave dimethyl 1-(4-acetylphenyl)-1H-pyrazole-3,4-dicarboxylate (2), which on bromination yielded the corresponding monobromoacetyl (3) and dibromoacetyl (4) derivatives. Both compounds 3 and 4 on reaction with thiourea and thioacetamide afforded the 2-amino- (5) and the 2-methyl- (6) thiazole derivatives respectively, while compound 3 on reaction with 2-aminothiazole gave the imidazothiazole 7. Compound 3 was converted into its azide (8), which on 1,3-dipolar cycloaddition with DMAD afforded the 1,2,3-triazole-4,5-dicarboxylate (9).

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Obenhuber, A. H., T. L. Gianetti, R. G. Bergman, and J. Arnold. "Regioselective [2+2] and [4+2] cycloaddition reactivity in an asymmetric niobium(bisimido) moiety towards unsaturated organic molecules." Chemical Communications 51, no. 7 (2015): 1278–81. http://dx.doi.org/10.1039/c4cc07851a.

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The asymmetric bis-imido structure and the lability of the diethyl ether linkage in complex 1 provide a niobium complex that undergoes regioselective [4+2] cycloaddition reactions with an α,β-unsaturated ketone and cycloaddition reactions that involve bond formation to the MAD ligand (MAD = monoazabutadiene).

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40

Wrackmeyer, Bernd, and Jürgen Süß. "1,1-Ethylborationof Diethynyl(dimethyl)silane: Formation of a Silole Followed by [4+2]Cycloadditions to 7-Silanorbornadienes and 7-Silanorbornenes." Zeitschrift für Naturforschung B 57, no. 7 (2002): 741–45. http://dx.doi.org/10.1515/znb-2002-0705.

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Diethynyl(dimethyl)silane, Me2Si(C≡C-H)2 2, reacts with triethylborane, Et3B 1, by 1,1- ethylboration to give a silole, 3-diethylboryl-4-ethyl-1,1-dimethyl-sila-2,4-cyclopentadiene 3, as a short-lived intermediate which reacts further with 2 or dimerises via [4+2]cycloadditions to the 7-silanorbornadiene 4 or the 7-silanorbornene derivatives 5, respectively. Since the silole 3 was not detected by NMR, the analogous reactions were studied using 1-alkynyl(ethynyl)- dimethylsilanes, Me2Si(C≡C-H)C≡C-R 6 [R = Bu (a), iPent (b), tBu (c)]. In these cases, 1,1-ethylboration gave the siloles 7a,b,c and

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Auner, Norbert, Armin W. Weingartner, and Eberhardt Herdtweck. "Silaheterocyclen, XXIV. / Silaheterocycles, XXIV." Zeitschrift für Naturforschung B 48, no. 3 (1993): 318–32. http://dx.doi.org/10.1515/znb-1993-0311.

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The 1-amino-2-neopentylsilenes 5-8 are formed in the reaction of LitBu with the aminovinylsilanes 1-4 in n-pentane (addition of LitBu to the vinylic double bond with subsequent 1,2-elimination of LiCl). The α-Li adducts initially formed are trapped by Me3SiOSO2CF3 to yield α-SiMe3-silanes. The silenes undergo insertion reactions into the Si—O bond of Me3SiOMe. In the absence of any trapping reagent dimerization occurs. One of the 1,3-disilacyclobutanes thus formed (15) could be examined by X-ray diffraction. Reacting with 1,3-butadienes the chlorosubstituted silenes 5 and 8 yield [2 + 2]-cyclo

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42

Corti, Vasco, Enrico Marcantonio, Martina Mamone, Alessandro Giungi, Mariafrancesca Fochi, and Luca Bernardi. "Synergistic Palladium-Phosphoric Acid Catalysis in (3 + 2) Cycloaddition Reactions between Vinylcyclopropanes and Imines." Catalysts 10, no. 2 (2020): 150. http://dx.doi.org/10.3390/catal10020150.

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The palladium-catalyzed (3 + 2) cycloaddition reaction between vinylcyclopropanes (VCPs) bearing geminal EWG’s and imines represents a straightforward and flexible entry to polysubstituted pyrrolidine derivatives. In this paper, we demonstrate that using a synergistic catalysis approach, based on the combination of phosphoric acid and palladium catalysts, it is possible to engage for the first time N-aryl and N-benzyl imines in this cycloaddition reaction. A range of polysubstituted pyrrolidines is obtained with moderate to good yields and diastereoselectivities, using a simple palladium speci

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43

Zezula, Josef, Tomáš Hudlický, and Ion Ghiviriga. "Intramolecular Diels-Alder Cycloadditions of cis-Cyclohexadienediols Derived Enzymatically from (2-Azidoethyl)benzene. Construction of Highly Functionalized Bridged Isoquinoline Synthons." Collection of Czechoslovak Chemical Communications 66, no. 8 (2001): 1269–86. http://dx.doi.org/10.1135/cccc20011269.

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(3aR,7aS)-4-(2-Azidoethyl)-2,2-dimethyl-3a,7a-dihydrobenzo[1,3]dioxole (22) was converted in two steps to trienes23and24, which upon heating underwent intramolecular Diels-Alder reactions to give mixtures of isomeric 11,11-dimethyl-5-oxo-10,12-dioxa-4-azatetracyclo[6.5.2.01,6.09,13]pentadec-14-ene-7-carboxylates25,26and27,28, respectively. These products were separated and identified. For comparison, intermolecular Diels-Alder cycloaddition of diene22with maleic anhydride was carried out. Products of this reaction, 1-(2-azidoethyl)-4,4-dimethyl-3,5,10-trioxatetracyclo[5.5.2.02,6.08,12]tetradec

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Nakazawa, Tomoo, Mariko Ashizawa, Fumiko Nishikawa, Mamoru Jinguji, Hideki Yamochi, and Ichiro Murata. "The reactions of 4,5-dehydrotropone with morpholine enamines. [2+2]cycloaddition reaction of dehydrotropone." Tetrahedron Letters 27, no. 26 (1986): 3005–8. http://dx.doi.org/10.1016/s0040-4039(00)84702-4.

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Cogan, Dillon P., Graham A. Hudson, Zhengan Zhang, et al. "Structural insights into enzymatic [4+2] aza-cycloaddition in thiopeptide antibiotic biosynthesis." Proceedings of the National Academy of Sciences 114, no. 49 (2017): 12928–33. http://dx.doi.org/10.1073/pnas.1716035114.

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The [4+2] cycloaddition reaction is an enabling transformation in modern synthetic organic chemistry, but there are only limited examples of dedicated natural enzymes that can catalyze this transformation. Thiopeptides (or more formally thiazolyl peptides) are a class of thiazole-containing, highly modified, macrocyclic secondary metabolites made from ribosomally synthesized precursor peptides. The characteristic feature of these natural products is a six-membered nitrogenous heterocycle that is assembled via a formal [4+2] cycloaddition between two dehydroalanine (Dha) residues. This heteroan

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46

Zahedifar, Mahboobeh, Hassan Sheibani, and Vahid Saheb. "Regioselectivity and Reactivity of Intramolecular [2+2] Cycloaddition Reactions of Acyl Ketenes: Experimental and Theoretical Studies." Synlett 29, no. 14 (2018): 1836–41. http://dx.doi.org/10.1055/s-0037-1610198.

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The regioselectivity of the intramolecular [2+2] cycloaddition reaction of acyl ketenes formed from metastable mesoionic 1,3-oxazinium-4-olates was investigated by experimental and theoretical methods. The ring opening of the mesoionic N-allyl-2-(2-arylvinyl)-1,3-oxazinium-4-olates led to the formation of unstable acyl ketenes. Although there are four possible paths for an intramolecular [2+2] cycloaddition reaction involving the two double bonds (vinyl and allyl), only the intramolecular [2+2] criss-cross cycloaddition reaction through the vinyl double bond occurred to give 3-allyl-3-azabic

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47

Li, Jin-Heng, De-Lie An, and Jing-Hao Qin. "Recent Advances in Cycloaddition Reactions with Alkynes to Construct Heterocycles." Synthesis 52, no. 24 (2020): 3818–36. http://dx.doi.org/10.1055/s-0040-1707355.

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Heterocyclic compounds, especially N-heterocycles and O-heterocycles, are prominent structural motifs present in numerous natural products and medically and/or economically important compounds. This review aims to describe the development of transition-metal-catalyzed cycloaddition reactions of functionalized m-atom partners with alkynes to access a wide range of five-, six-, and seven-membered heterocycles, that is functionalized N-heterocycles and O-heterocycles such as azepines, isoquinolines, isocoumarins, spiroheterocycles, indoles, furans, and pyrroles, in a selectively controlled manner

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48

Masoumifar, Sepideh, Mina Haghdadi, and Hassan Ghasemnejad Bosra. "Computational Study on the Mechanism of Cycloaddition Reactions of Bissulfonyl-1,3-butadiene with Some Alkenes." Letters in Organic Chemistry 17, no. 10 (2020): 735–42. http://dx.doi.org/10.2174/1570178617666200210112307.

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The cycloaddition reactions of 2,3-bis (ethylene sulfonyl)-1,3-butadiene with 2,3-dimethyl- 1,3-butadiene, cyclopentadiene, 2-methyl prop-2-enoate and ethyl vinyl ether have been theoretically studied using the DFT method at the MPWB1K/cc-pVDZ level of theory. There are two possible modes of participation in each reaction (2π and 4π electron), of which the 2π electron is preferred. The energy results indicate that formations of the [2+4] cycloadducts are favored kinetically. The stereoselectivity of the [2+4] cycloaddition reaction of 2,3-bis (ethylene sulfonyl)-1,3-butadiene with cyclopentane

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49

Hayashi, Saori, Akira Mori, Masatoshi Nishina, Masanori Sumimoto, Kenzi Hori, and Hidetoshi Yamamoto. "Regio- and diastereo-selective formation of Isoxazoline Derivatives by Lewis acid Mediated 1,3-dipolar Cycloaddition Reactions of Nitrile Oxide." Journal of Chemical Research 2007, no. 7 (2007): 394–96. http://dx.doi.org/10.3184/030823407x228759.

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In the presence of magnesium perchlorate, 1,3-dipolar cycloaddition reactions of nitrile oxides to crotonamide bearing 4-benzyl-5,5-dimethyl-1,3-oxazolidin-2-one as the chiral auxiliary proceeded with a regio- and diastereo-selective manner to afford the corresponding chiral 2-isoxazoline. The mechanisms underlying the diastereoface selection in the cycloaddition reaction were investigated using the B3LYP/6-31G* level of theory.

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50

Xiao, Ben-Xian, Bo Jiang, Xue Song, Wei Du, and Ying-Chun Chen. "Phosphine-catalysed asymmetric dearomative formal [4+2] cycloadditions of 3-benzofuranyl vinyl ketones." Chemical Communications 55, no. 21 (2019): 3097–100. http://dx.doi.org/10.1039/c9cc00386j.

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