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Journal articles on the topic '[2 + 2] and [4 + 2] cycloadditions reactions. Diels-Alder reactions'

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Published: 4 June 2021

Last updated: 17 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

Spino, Claude, and Jason Crawford. "2-Carbomethoxy-1,3-butadiene: an electronically activated diene in [4 + 2] cycloadditions with electron-deficient dienophiles." Canadian Journal of Chemistry 71, no. 7 (1993): 1094–97. http://dx.doi.org/10.1139/v93-145.

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Cross Diels–Alder reactions between 2-carbomethoxy-1,3-butadiene 1 and electron-rich dienes were carried out. It was found that diene 1 had a higher reactivity than even the well-known Danishefsky diene in its Diels–Alder cycloaddition with electron-deficient dienophiles. In addition, (Z)-1-methylthio-3-carbomethoxy-1,3-butadiene 11 was found to have a higher reactivity than (Z)-1-methylthio-1,3-butadiene and (Z)-2-carbomethoxy-1,3-hexadiene, while both (E)- and (Z)-1,2-(bis)-carbomethoxy-1,3-butadiene 14 reacted efficiently with maleic anhydride to give the corresponding cy-cloadduct 15.

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3

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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4

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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5

Yang, Zhongyue, Song Yang, Peiyuan Yu, et al. "Influence of water and enzyme SpnF on the dynamics and energetics of the ambimodal [6+4]/[4+2] cycloaddition." Proceedings of the National Academy of Sciences 115, no. 5 (2018): E848—E855. http://dx.doi.org/10.1073/pnas.1719368115.

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SpnF is the first monofunctional Diels–Alder/[6+4]-ase that catalyzes a reaction leading to both Diels–Alder and [6+4] adducts through a single transition state. The environment-perturbed transition-state sampling method has been developed to calculate free energies, kinetic isotope effects, and quasi-classical reaction trajectories of enzyme-catalyzed reactions and the uncatalyzed reaction in water. Energetics calculated in this way reproduce the experiment and show that the normal Diels–Alder transition state is stabilized by H bonds with water molecules, while the ambimodal transition state

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6

Himbert, Gerhard, and Hans-Jürgen Schlindwein. "Cycloadditionen, XX Thermisch induzierte intramolekulare Reaktionen bei 2-Methyl-2,3-butadienamiden / Cycloadditions, XX Thermally Induced Intramolecular Reactions of 2-Methyl-2,3-butadienamides." Zeitschrift für Naturforschung B 47, no. 12 (1992): 1785–94. http://dx.doi.org/10.1515/znb-1992-1224.

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The 2-methyl-2,3-butadienamides 4a—m are directly synthesized by the reaction of the corresponding allenic acid chloride 2 with the secondary amines 3. At heating, 4a—j undergo the intramolecular Diels-Alder reaction, by using their ω-standing double bond and the π-system of the directly bonded phenyl groups or of the “methylenic” bonded arenes or furans. Thereby the tricycles 6a—g (bearing five-membered lactam moreties) and/or the tricycles 7-9 (bearing six-membered lactam moreties) are formed. The influence of the geminai methyl group on the chemoselectivity and on the velocity of the IMDA r

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7

TOMÉ, AUGUSTO C., PAULA S. S. LACERDA, ANA M. G. SILVA, MARIA G. P. M. S. NEVES, and JOSÉ A. S. CAVALEIRO. "Synthesis of new tetrapyrrolic derivatives—porphyrins as dienophiles or dipolarophiles." Journal of Porphyrins and Phthalocyanines 04, no. 05 (2000): 532–37. http://dx.doi.org/10.1002/1099-1409(200008)4:5<532::aid-jpp267>3.0.co;2-0.

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Porphyrins participate as dienophiles in Diels-Alder reactions with ortho-quinodimethanes or pentacene. They can also behave as dipolarophiles in 1,3-dipolar cycloadditions with a range of 1,3-dipoles. These two reaction types were successfully used to synthesize novel chlorins, bacteriochlorins and isobacteriochlorins.

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8

Burford, Neil, Charles L. B. Macdonald, Trenton M. Parks, et al. "Preparation and structure of 2-chloro-1,3-dimethyldiaza-2-arsenane, 1,3-dimethyldiaza-2-arsenanium tetrachlorogallate, and butadiene cycloadducts of diazarsenium cations." Canadian Journal of Chemistry 74, no. 11 (1996): 2209–16. http://dx.doi.org/10.1139/v96-248.

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1,3-Dimethyldiaza-2-arsenanium tetrachlorogallate (crystal data: C5H12AsCl4GaN2, M = 386.61, orthorhombic, space group Pca21, a = 14.432(3) Å, b = 6.7580(14) Å, c = 13.905(3) Å, V = 1356.2(5) Å3) is synthesized by the routine chloride ion abstraction procedure from 2-chloro-1,3-dimethyldiaza-2-arsenane (crystal data: C5H12AsClN2, M = 210.54, monoclinic, space group P21/n, a = 7.206(1) Å, b = 9.650(1) Å, c = 13.021(2) Å, β = 99.61(2)°, V = 892.8(2) Å3). X-ray crystallographic studies of both compounds are described together with that for 2-chloro-1,3-dimethyldiaza-2-arsolidine (crystal data: C4

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9

Escalante, Carlos H., Eder I. Martínez-Mora, Carlos Espinoza-Hicks, et al. "Highly selective Diels–Alder and Heck arylation reactions in a divergent synthesis of isoindolo- and pyrrolo-fused polycyclic indoles from 2-formylpyrrole." Beilstein Journal of Organic Chemistry 16 (June 17, 2020): 1320–34. http://dx.doi.org/10.3762/bjoc.16.113.

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A highly regio-, chemo- and stereoselective divergent synthesis of isoindolo- and pyrrolo-fused polycyclic indoles is herein described, starting from 2-formylpyrrole and employing Diels–Alder and Heck arylation reactions. 3-(N-Benzyl-2-pyrrolyl)acrylates and 4-(pyrrol-2-yl)butenones underwent a highly endo-Diels–Alder cycloaddition with maleimides to furnish octahydropyrrolo[3,4-e]indoles, which served as precursors in the regioselective synthesis of aza-polycyclic skeletons via an intramolecular Heck arylation reaction. Through the latter reaction, the 3-(N-benzyl-2-pyrrolyl)acrylates give ri

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10

Begum, Imtiaz, Tim Kalisch, Gregor Schnakenburg, Zsolt Kelemen, László Nyulászi, and Rainer Streubel. "[4 + 2]-Cycloadditions of a thiazol-based tricyclic 1,4-diphosphinine and a new easy 1,4-diphosphinine protection deprotection strategy." Dalton Transactions 49, no. 36 (2020): 12776–79. http://dx.doi.org/10.1039/d0dt02529a.

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Diels–Alder-reactions of a thiazol-2-thione-based, tricyclic 1,4-diphosphinine were investigated, showing that the central aromatic π-system can react with various dienophiles. In one case, photochemical deprotection of the 1,4-diphosphinine was found.

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11

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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12

Beck, Janina, Olaf Fuhr, Martin Nieger, and Stefan Bräse. "A versatile Diels–Alder approach to functionalized hydroanthraquinones." Royal Society Open Science 7, no. 11 (2020): 200626. http://dx.doi.org/10.1098/rsos.200626.

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The synthesis of highly substituted hydroanthraquinone derivatives with up to three stereogenic centres via a Diels–Alder reaction, starting from easily accessible 2-substituted naphthoquinones, is described. The [4+2]-cycloaddition is applicable for a broad range of substrates, runs under mild conditions and results in high yields. The highly regioselective outcome of the reactions is enabled by a benzoyl substituent at C2 of the dienophiles. The obtained hydroanthraquinones can be further modified and represent ideal substrates for follow-up intramolecular coupling reactions to create unique

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13

Mayr, Herbert, Armin R. Ofial, Jürgen Sauer, and Bernhard Schmied. "[2++4] Cycloadditions of Iminium Ions − Concerted or Stepwise Mechanism of Aza Diels−Alder Reactions?" European Journal of Organic Chemistry 2000, no. 11 (2000): 2013–20. http://dx.doi.org/10.1002/1099-0690(200006)2000:11<2013::aid-ejoc2013>3.0.co;2-a.

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14

de Sousa, Andrea L. F., José E. P. Cardoso Filho, Blanka Wladislaw, Liliana Marzorati, and Claudio Di Vitta. "Studies on chemo- and diastereo-selectivity of the Diels–Alder reactions of sulfinyltoluquinones with cyclopentadiene." Canadian Journal of Chemistry 87, no. 8 (2009): 1135–43. http://dx.doi.org/10.1139/v09-070.

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Sulfinyltoluquinones (2a–2c) were submitted to thermal or catalyzed [4+2] cycloaddition reactions with cyclopentadiene. For p-tolylsulfinyltoluquinones (2b) and (2c), almost complete C2–C3-chemo- and unlike-diastereoselectivity was achieved by catalysis with ZnBr2, yielding adducts 6. Under thermal conditions, Diels–Alder reaction took place at the C5–C6 double bonds of quinones 2a–2c, generating mixtures of diastereoisomeric like- and unlike-adducts 4.

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15

Kiran, I. N. Chaithanya, R. Santhosh Reddy, Chandraiah Lagishetti, Huacheng Xu, Zhen Wang, and Yun He. "Selective Aza Diels–Alder and Domino [4+2]/[2+2] Cycloaddition Reactions of Arynes with N-Sulfonyl Ketimines." Journal of Organic Chemistry 82, no. 3 (2017): 1823–32. http://dx.doi.org/10.1021/acs.joc.6b02667.

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16

Gribble, Gordon W., Daniel J. Keavy, Stephen E. Branzt, William J. Kelly, and Mark A. Pals. "Unexpected regioselective diels-alder cycloaddition reactions between 3-fluorobenzyne and 2-alkylfurans." Tetrahedron Letters 29, no. 48 (1988): 6227–30. http://dx.doi.org/10.1016/s0040-4039(00)82311-4.

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17

Amos, David T., Adam R. Renslo, and Rick L. Danheiser. "Intramolecular [4 + 2] Cycloadditions of Iminoacetonitriles: A New Class of Azadienophiles for Hetero Diels−Alder Reactions." Journal of the American Chemical Society 125, no. 17 (2003): 4970–71. http://dx.doi.org/10.1021/ja034629o.

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18

Umstead, Weston J., Olga A. Mukhina, N. N. Bhuvan Kumar, and Andrei G. Kutateladze. "Photoinduced Cycloadditions in the Diversity-Oriented Synthesis Toolbox: Increasing Complexity with Straightforward Post-Photochemical Modifications." Australian Journal of Chemistry 68, no. 11 (2015): 1672. http://dx.doi.org/10.1071/ch15266.

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Rapid growth of complexity and unprecedented molecular architectures is realised via the excited state intramolecular proton transfer (ESIPT) in o-acylamidobenzaldehydes and ketones followed by [4+2] or [4+4] cycloadditions with subsequent post-photochemical modifications. The approach is congruent with diversity-oriented synthesis, whereby photoprecursors are synthesised in a modular fashion allowing for up to four diversity inputs. The complexity of the primary photoproducts is further enhanced using straightforward and high-yielding post-photochemical modification steps such as reactions wi

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19

García, M. Martínez, R. Cruz-Almanza, F. Lara-Ochoa, et al. "Ferrocene Derivatives in Diels-Alder [4+2] Cycloaddition Reactions to Fullerenes C60and C70." Fullerene Science and Technology 7, no. 5 (1999): 897–908. http://dx.doi.org/10.1080/10641229909351386.

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20

Hou, Ji-Qin, Jiang-Hong Yu, Heng Zhao, et al. "Biomimetic total syntheses of baefrutones A–D, baeckenon B, and frutescones A, D–F." Organic & Biomolecular Chemistry 18, no. 6 (2020): 1135–39. http://dx.doi.org/10.1039/c9ob02490e.

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Biomimetic total syntheses of the natural tasmanone-based meroterpenoids were achieved for the first time via Michael addition, oxidative [4 + 2] cycloaddition, and water-promoted Diels–Alder click reactions.

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21

Ward, Dale E., Thomas E. Nixey, Yuanzhu Gai, Matthew J. Hrapchak, and M. Saeed Abaee. "Intramolecular Diels–Alder reactions of 2H-thiopyran dienes." Canadian Journal of Chemistry 74, no. 7 (1996): 1418–36. http://dx.doi.org/10.1139/v96-160.

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A systematic survey of IMDA reactions of 4-[tris(2-methylethyl)silyl]oxy-2H-thiopyran derivatives with potential dienophiles tethered at the C-2, C-3, C-5, and C-6 positions is presented. Cycloaddition was not observed with a C3 or C4 tether and an unactivated terminal olefin as dienophile. IMDA adducts could be obtained when dienophiles activated by a carbomethoxy group were employed. Compounds having the activated dienophile attached via a C3 tether to C-2 of the 2H-thiopyran gave adducts with high stereoselectivity. Substrates having the dienophile attached to C-3 with a C3 or C4 tether cyc

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22

Brossard, Dominique, Pascal Retailleau, Vincent Dumontet, Philippe Breton, Sandy Desrat, and Fanny Roussi. "Fast & easy preparation of 3D scaffolds from methyl benzoate by a diversity oriented synthesis strategy based on Diels–Alder and ene-reactions." Organic & Biomolecular Chemistry 15, no. 26 (2017): 5585–92. http://dx.doi.org/10.1039/c7ob01236e.

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23

Grobe, Joseph, Duc Le Van, and Joachim Schulze. "Diels- Aider- Addukte des Diphosphens F3CP = PCF3 / Diels-Alder Adducts of the Diphosphene F3P =PCF3." Zeitschrift für Naturforschung B 40, no. 12 (1985): 1753–55. http://dx.doi.org/10.1515/znb-1985-1227.

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Abstract The heterocycles 3 to 6 are formed in a one-pot procedure by reacting trifluoromethyl phosphorus diiodide F3CPI2 with tin dichloride SnCl2 in the presence of the corresponding 1,3-dienes. The reactions proceed via [2+4] cycloaddition of the diphosphene intermediate F3CP = PCF3 (1) as suggested by the high yields obtained (50 to 100%) and the formation of the cyclic tetraphosphane (F3CP)4 (2) as the only by-product. Cycloreversion occurs at moderate temperatures as demonstrated by the reaction of 6 with 2,3-dimethylbutadiene to give 3 and cyclohexadiene. The products have been characte

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24

Padwa, A. "Application of cascade processes toward heterocyclic synthesis." Pure and Applied Chemistry 75, no. 1 (2003): 47–62. http://dx.doi.org/10.1351/pac200375010047.

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The reactions of N-acyliminium ions with tethered π-bonds are among the most important methods for preparing complex nitrogen-containing heterocycles. Pummerer-based cyclizations are also finding widespread application in both carbo- and heterocyclic syntheses. As part of a program concerned with new methods for alkaloid synthesis, we became interested in using a linked Pummerer/N-acyliminium ion cyclization sequence since we felt that this combination offers unique opportunities for the assemblage of complex target molecules. A synthetic method that combines transformations of different react

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25

El Ghozlani, Mohamed, Ali Barhoumi, Reda Elkacmi, Anas Ouled Aitouna, Abdellah Zeroual, and Mohammed El Idrissi. "Mechanistic Study of Hetero-Diels–Alder [4 + 2] Cycloaddition Reactions Between 2-Nitro-1H-Pyrrole and Isoprene." Chemistry Africa 3, no. 4 (2020): 901–9. http://dx.doi.org/10.1007/s42250-020-00187-8.

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26

Leigh, William J. "Organic reactions in liquid crystalline solvents. 2. An investigation into the use of liquid crystalline solvents to effect stereochemical control in the Diels–Alder reaction." Canadian Journal of Chemistry 63, no. 10 (1985): 2736–41. http://dx.doi.org/10.1139/v85-455.

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The possibility of using liquid crystalline solvents to control the stereospecificity of bimolecular reactions as a result of differences in liquid crystalline solvation of the various possible transition states has been examined. The Diels–Alder reactions of 2,5-dimethyl-3,4-diphenylcyclopentadienone with four dienophiles of varying steric size (cyclopentene, cycloheptene, indene, and acenaphthylene) have been carried out in benzene, cholesteryl nonanoate (isotropic), cholesteryl propionate (cholesteric), and 4-ethyl-4′-(4-pentylcyclohexyl)biphenyl (smectic) at 105 °C. In spite of very large

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27

Solujic, L., Emil B. Milosavljevic, John H. Nelson, Nathaniel W. Alcock, and Jean Fischer. "Intramolecular [4 + 2] Diels-Alder cycloaddition reactions of phospholes with vinylphosphines promoted by nickel." Inorganic Chemistry 28, no. 18 (1989): 3453–60. http://dx.doi.org/10.1021/ic00317a012.

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Gill, Melvyn, Peter M. Morgan, Jin Yu, and Jonathan M. White. "Pigments of Fungi. XLVII. Cardinalic Acid, a New Anthraquinone Carboxylic Acid from the New Zealand Toadstool Dermocybe cardinalis and the Synthesis and X-Ray Crystal Structure of Methyl 1,7,8-Tri-O-methylcardinalate." Australian Journal of Chemistry 51, no. 3 (1998): 213. http://dx.doi.org/10.1071/c97154.

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Cardinalic acid (1,7,8-trihydroxy-6-methoxy-3-methyl-9,10-dioxoanthracene-2-carboxylic acid) (4) and the known anthraquinone carboxylic acids endocrocin (1), dermolutein (2) and cinnalutein (3) have been isolated from the New Zealand toadstool Dermocybe cardinalis. Methyl 1,7,8-tri-O-methylcardinalate (5) has been prepared both by permethylation of the natural product (4) and from 2,6-dichloro-1,4-benzoquinone by two consecutive regioselective Diels–Alder cycloaddition reactions. A single-crystal X-ray structure analysis of the ester (5) corroborates the structure of the natural product (4) an

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29

Borisova, Kseniya K., Eugeniya V. Nikitina, Roman A. Novikov, et al. "Diels–Alder reactions between hexafluoro-2-butyne and bis-furyl dienes: kinetic versus thermodynamic control." Chemical Communications 54, no. 23 (2018): 2850–53. http://dx.doi.org/10.1039/c7cc09466c.

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30

Wu, Xiang, Shi-Bao Zhao, Lang-Lang Zheng та You-Gui Li. "Oxidative Asymmetric Formal Aza-Diels–Alder Reactions of Tetrahydro-β-carboline with Enones in the Synthesis of Indoloquinolizidine-2-ones". Molecules 23, № 9 (2018): 2228. http://dx.doi.org/10.3390/molecules23092228.

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Ru-catalyzed tandem amine oxidative dehydrogenation/formal aza-Diels–Alder reaction for enantio- and diastereoselective synthesis of indoloquinolizidine-2-ones from tetrahydro-β-carbolines and α,β-unsaturated ketones is described. The reaction proceeds via tandem ruthenium-catalyzed amine dehydrogenation using tert-butyl hydroperoxide (TBHP) as the oxidant and a chiral thiourea-catalyzed formal aza-[4 + 2] cycloaddition, providing a step-economical strategy for the synthesis of these valuable heterocyclic products.

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31

McLellan, Jill F., Roy M. Mortier, Stefan T. Orszulike, and R. Michael Paton. "Tandem Ene Addition/Diels-Alder Cycloaddition reactions of Methyl Linoleate with 4-Phenyl-1,2,4-Triazoline-3,5-Dione and Diethyl Azodicarboxylate." Journal of Chemical Research 2000, no. 7 (2000): 339–41. http://dx.doi.org/10.3184/030823400103167552.

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Treatment of methyl linoleate with 4-phenyl-1,2,4-triazoline-3,5-dione affords 1:1 adducts resulting from ene addition, and 1:2 adducts formed by ene addition followed by Diels Alder cycloaddition. The corresponding reaction of diethyl azodicarboxylate yields predominantly 1:1 ene products.

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32

Xiong, Xing Quan. "Efficient Synthesis of Dendritic Architectures by One-Pot Double Click Reactions." Australian Journal of Chemistry 62, no. 10 (2009): 1371. http://dx.doi.org/10.1071/ch09052.

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Dendritic macromolecules with 8 and 16 hydroxy end-groups on the periphery have been synthesized using double click reactions (Cu-catalyzed azide/alkyne click chemistry, i.e., CuAAC and Diels–Alder [4 + 2] cycloaddition reactions) with a one-pot technique. The structure of the dendrimers was characterized by 1H and 13C NMR spectroscopy, and matrix-assisted laser desorpton–ionization time-of-flight mass spectrometry. The purity was determined by size exclusion chromatography.

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33

Halton, B., and SGG Russell. "Studies in the Cycloproparene Series: Cycloaddition Reactions With 1,3-Diphenylisobenzofuran." Australian Journal of Chemistry 43, no. 12 (1990): 2099. http://dx.doi.org/10.1071/ch9902099.

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The behaviour of cyclopropabenzene (1) with 1,3-diphenylisobenzofuran ( dpibf ) is temperature dependent. Addition to the strained bridge bond of (1) gives the Diels -Alder adduct (13) in tetrahydrofuran at 20°C, but in chloroform at the same temperature the ring-expanded 5,10-epoxydibenzocycloheptene (12) is also formed. Compound (12) becomes the sole product from reaction at 30°C or higher. Cyclopropa [b]naphthalene (2) is inert to dpibf under similar conditions but provides the dimer 6,13-dihydropentacene (15). The triazoloindazole (19) results from reaction of (2) with 4-phenyl-3H-1,2,4-tr

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Mancini, Pedro M. E., Carla M. Ormachea, and María N. Kneeteman. "Polar Diels-Alder Reactions Under Microwave Irradiation Employing Different Heterocyclic Compounds as Electrophiles." Mini-Reviews in Organic Chemistry 16, no. 6 (2019): 527–43. http://dx.doi.org/10.2174/1570193x15666180608083925.

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During the last twenty years, our research group has been working with aromatic nitrosubstituted compounds acting as electrophiles in Polar Diels-Alder (P-DA) reactions with different dienes of diverse nucleophilicity. In this type of reaction, after the cycloaddition reaction, the nitrated compounds obtained as the [4+2] cycloadducts suffer cis-extrusion with the loss of nitrous acid and a subsequent aromatization. In this form, the reaction results are irreversible. On the other hand, the microwave-assisted controlled heating become a powerful tool in organic synthesis as it makes the reacti

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Chopra, Radhika, Kamaldeep Sharma, Manoj Kumar, and Vandana Bhalla. "Pentacenequinone-Stabilized Silver Nanoparticles: A Reusable Catalyst for the Diels–Alder [4 + 2] Cycloaddition Reactions." Journal of Organic Chemistry 81, no. 3 (2016): 1039–46. http://dx.doi.org/10.1021/acs.joc.5b02495.

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Hilt, Gerhard, Wilfried Hess, Thomas Vogler, and Christoph Hengst. "Ligand and solvent effects on cobalt(I)-catalysed reactions: Alkyne dimerisation versus [2+2+2]-cyclotrimerisation versus Diels–Alder reaction versus [4+2+2]-cycloaddition." Journal of Organometallic Chemistry 690, no. 23 (2005): 5170–81. http://dx.doi.org/10.1016/j.jorganchem.2005.03.067.

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Zagidullin, Almaz, Vasili Miluykov, Elena Oshchepkova, Artem Tufatullin, Olga Kataeva, and Oleg Sinyashin. "Enhancing the reactivity of 1,2-diphospholes in cycloaddition reactions." Beilstein Journal of Organic Chemistry 11 (January 27, 2015): 169–73. http://dx.doi.org/10.3762/bjoc.11.17.

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Two different approaches have been employed to enhance the reactivity of 1-alkyl-1,2-diphospholes – the introduction of electron-withdrawing groups either at the phosphorus atoms or in the para-position of the arene ring. The alkylation of sodium 1,2-diphospha-3,4,5-triphenylcyclopentadienide with alkyl halides Hal-CH2-R (R = CN, COOEt, OMe, CH2OEt) results in corresponding 1-alkyl-3,4,5-triphenyl-1,2-diphospholes (alkyl = CH2CN (1a), CH2COOEt (1b), CH2OMe (1c), and (CH2)2OEt (1d)), which spontaneously undergo the intermolecular [4 + 2] cycloaddition reactions at room temperature to form the m

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Su, Ming-Der. "Theoretical Study of Intramolecular [4 + 2] Cycloadditions of Iminoacetonitriles: A New Class of Azadienophiles for Hetero Diels−Alder Reactions." Organometallics 23, no. 10 (2004): 2507–9. http://dx.doi.org/10.1021/om030675l.

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Bogdanowicz-Szwed, Krystyna, та Aleksandra Pałasz. "Synthesis of 3,4-Dihydro-2H-pyrans by Hetero-Diels-Alder Reactions of Functionalized α,β-Unsaturated Carbonyl Compounds with Styrenes". Zeitschrift für Naturforschung B 56, № 4-5 (2001): 416–22. http://dx.doi.org/10.1515/znb-2001-4-515.

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Abstract Cycloadditions of 3-aryl-2-benzoyl-2-propenenitriles 1a,b to styrene (2a) and its methyl or methoxy-substituted derivatives 2b-d proceed regio- and diastereoselectively yielding cis and trans diastereoisomers of 2,4,6-triaryl-3,4-dihydro-2H-pyran-5-carbonitriles 3 and 4 in 59-72% yield. Cycloadducts cis-3 were the major products. Reaction of 5-(4-nitrobenzylidene)-1,3-dimethylbarbituric acid (5) with styrenes 2a-d afforded diastereoisomeric mixtures of 2H-pyrano[2,3-d]pyrimidine-2,4(3H)-diones cis-6 and trans-7 in 71 - 78% yield.

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Rahn, Jeffrey A., Mark S. Holt, George A. Gray, Nathaniel W. Alcock, and John H. Nelson. "Intramolecular [4 + 2] Diels-Alder cycloaddition reactions of phospholes with vinylphosphines promoted by palladium and platinum." Inorganic Chemistry 28, no. 2 (1989): 217–26. http://dx.doi.org/10.1021/ic00301a013.

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Lemos, Aline B., Regina Sparrapan, and Marcos N. Eberlin. "Reactions of gaseous acylium ions with 1,3-dienes: further evidence for polar [4 + 2+] Diels-Alder cycloaddition." Journal of Mass Spectrometry 38, no. 3 (2003): 305–14. http://dx.doi.org/10.1002/jms.442.

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Gültekіn, Z. "Iron (III)-doped montmorillonite catalysis of alkenes bearing sulphoxide groups in Diels-Alder reactions." Clay Minerals 39, no. 3 (2004): 345–48. http://dx.doi.org/10.1180/0009855043930139.

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AbstractFe3+-doped K10 montmorillonite combined with 2,6-di-tert-butyl-4-methyl-phenol is a potent catalytic system for trans-2-methylene-1,3-dithiolane 1,3-dioxide as a dienophile. Cycloaddition occurs with cyclopentadiene and furan as a diene at room temperature in short time and with good yields (64% overall).

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Padwa, A. "Tandem methodology for heterocyclic synthesis." Pure and Applied Chemistry 76, no. 11 (2004): 1933–52. http://dx.doi.org/10.1351/pac200476111933.

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Tandem methodology for heterocyclic synthesis represents a powerful approach for the rapid buildup of molecular complexity from potentially simple starting materials. Work from our laboratory has shown that the rhodium(II)-catalyzed cyclization cascade of alpha-diazo imides represents an effective method for the synthesis of a variety of heterocyclic systems. As an extension of these studies, we became interested in using a linked Pummerer/N-acyliminium ion cyclization sequence since we felt that this combination offers unique opportunities for the assemblage of complex target molecules. A syn

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Boger, Dale L., and Wendy L. Corbett. "4.pi. Participation of 1-aza-1,3-butadienes in [4 + 2] cycloaddition reactions: intramolecular Diels-Alder reactions of .alpha.,.beta.-unsaturated N-sulfonylimines." Journal of Organic Chemistry 58, no. 8 (1993): 2068–74. http://dx.doi.org/10.1021/jo00060a022.

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Singleton, Daniel A. "A [4 + 3] transition state for a [4 + 2] cycloaddition. A new secondary orbital interaction in Diels-Alder reactions." Journal of the American Chemical Society 114, no. 16 (1992): 6563–64. http://dx.doi.org/10.1021/ja00042a049.

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Pindur, Ulf, and Diana Keilhofer. "New Studies and a Reinvestigation on [4+2] Cycloadditions of (−)-Thebaine: Asymmetrical Diels-Alder Reactions with a Conformationally Fixed Chiral Diene." Liebigs Annalen der Chemie 1993, no. 9 (1993): 947–53. http://dx.doi.org/10.1002/jlac.1993199301151.

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Antol, Ivana, Luka Barešić, Zoran Glasovac, and Davor Margetić. "Computational Study of Electronic Influence of Guanidine Substitution on Diels-Alder Reactions of Heterocyclic Dienes." Croatica chemica acta 92, no. 2 (2019): 279–86. http://dx.doi.org/10.5562/cca3570.

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Quantum-chemical calculations of cycloaddition properties of cyclic heterodienes substituted with guanidine functionality were carried out. Molecular and electronic structures of series of dienes (pyrrole, furan, thiophene, isoindole and 1,3-butadiene) were calculated and reactivity order established on the basis of FMO theory. Transition state calculations of model [4+2] cycloaddition reaction with acetylene indicate that guanidine substitution influences reaction barriers in moderate extent (up to ~4 kcal mol–1). The substitution position plays an important role on the sign and magnitude of

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Mlostoń, Grzegorz, Katarzyna Urbaniak, Malwina Sobiecka, et al. "Hetero-Diels-Alder Reactions of In Situ-Generated Azoalkenes with Thioketones; Experimental and Theoretical Studies." Molecules 26, no. 9 (2021): 2544. http://dx.doi.org/10.3390/molecules26092544.

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The hetero-Diels-Alder reactions of in situ-generated azoalkenes with thioketones were shown to offer a straightforward method for an efficient and regioselective synthesis of scarcely known N-substituted 1,3,4-thiadiazine derivatives. The scope of the method was fairly broad, allowing the use of a series of aryl-, ferrocenyl-, and alkyl-substituted thioketones. However, in the case of N-tosyl-substituted cycloadducts derived from 1-thioxo-2,2,4,4-tetramethylcyclobutan-3-one and the structurally analogous 1,3-dithione, a more complicated pathway was observed. By elimination of toluene sulfinic

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Boger, Dale L., and Monica J. Kochanny. "Inverse Electron Demand Diels-Alder Reactions of Heterocyclic Azadienes: [4 + 2] Cycloaddition Reaction of Amidines with 1,3,5-Triazines." Journal of Organic Chemistry 59, no. 17 (1994): 4950–55. http://dx.doi.org/10.1021/jo00096a044.

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Donckele, Etienne J., Aaron D. Finke, Laurent Ruhlmann, Corinne Boudon, Nils Trapp, and François Diederich. "The [2 + 2] Cycloaddition–Retroelectrocyclization and [4 + 2] Hetero-Diels–Alder Reactions of 2-(Dicyanomethylene)indan-1,3-dione with Electron-Rich Alkynes: Influence of Lewis Acids on Reactivity." Organic Letters 17, no. 14 (2015): 3506–9. http://dx.doi.org/10.1021/acs.orglett.5b01598.

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