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Journal articles on the topic 'Diels-Alder'

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Author: Grafiati

Published: 4 June 2021

Last updated: 22 June 2024

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1

Cai, Quan, Xu-Ge Si, and Zhi-Mao Zhang. "Asymmetric Inverse-Electron-Demand Diels–Alder Reactions of 2-Pyrones by Lewis Acid Catalysis." Synlett 32, no. 10 (January 24, 2021): 947–54. http://dx.doi.org/10.1055/a-1371-4391.

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AbstractDiels–Alder reactions of 2-pyrones with alkenes can provide highly functionalized [2,2,2]-bicyclic lactones under mild reaction conditions. Synthetic utilizations of these reactions have been well demonstrated in natural-product synthesis. Although several catalytic asymmetric strategies have been realized, current research in this area is still largely underdeveloped. Recent advances in enantioselective inverse-electron-demand Diels–Alder reactions with Lewis acid catalysis are reviewed.1 Introduction2 State of the Art of Enantioselective Diels–Alder Reactions of 2-Pyrones by Lewis Acid Catalysis3 Enantioselective Synthesis of Arene cis-Dihydrodiols by Diels–Alder/Retro-Diels–Alder Reactions of 2-Pyrones4 Enantioselective Synthesis of cis-Decalin Derivatives by Diels–Alder Reactions of 2-Pyrones5 Conclusions

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2

Han, Jianguang, Alexander Jones, and Xiaoguang Lei. "Recent Advances in the Total Synthesis of Prenylflavonoid and Related Diels–Alder Natural Products." Synthesis 47, no. 11 (April 13, 2015): 1519–33. http://dx.doi.org/10.1055/s-0034-1378696.

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This review summarizes the application of different strategies for the key Diels–Alder cycloaddition in prenylflavonoid and related Diels–Alder natural products synthesis, highlighting the application of novel methodologies and innovative strategies in the synthesis of these natural products and their analogues.1 Introduction2 Classical Conditions for the Diels–Alder Cycloaddition2.1 Thermal Promotion2.2 High-Pressure Promotion2.3 Brønsted Acid Catalysis3 Modern Approaches to the Diels–Alder Cycloaddition3.1 Electron-Transfer Initiation3.2 Silver-Nanoparticle Catalysis3.3 Chiral-Boron-Complex Promotion4 Conclusion

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3

Cain, David, Calum McLaughlin, John Molloy, Cameron Carpenter-Warren, Niall Anderson, and Allan Watson. "A Cascade Suzuki–Miyaura/Diels–Alder Protocol: Exploring the Bifunctional Utility of Vinyl Bpin." Synlett 30, no. 07 (October 24, 2018): 787–91. http://dx.doi.org/10.1055/s-0037-1611228.

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Cascade reactions are an important strategy in reaction design, allowing streamlining of chemical synthesis. Here we report a cascade Suzuki–Miyaura/Diels–Alder reaction, employing vinyl Bpin as a bifunctional reagent in two distinct roles: as an organoboron nucleophile for cross-coupling and as a Diels–Alder dienophile. Merging these two reactions enables a rapid and operationally simple synthesis of functionalized carbocycles in good yield. The effect of the organoboron subtype on Diels–Alder regioselectivity was investigated and postsynthetic modifications were carried out on a model substrate. The potential for a complementary Heck/Diels–Alder process was also assessed.

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4

Cao, Min-Hui, Nicholas J. Green, and Sheng-Zhen Xu. "Application of the aza-Diels–Alder reaction in the synthesis of natural products." Organic & Biomolecular Chemistry 15, no. 15 (2017): 3105–29. http://dx.doi.org/10.1039/c6ob02761j.

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5

Spino, Claude, Bryan Hill, Pascal Dubé, and Stéphane Gingras. "A diene-transmissive approach to the quassinoid skeleton." Canadian Journal of Chemistry 81, no. 1 (January 1, 2003): 81–108. http://dx.doi.org/10.1139/v02-196.

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Several tetracyclic molecules were prepared by diene-transmissive DielsAlder cycloadditions. Control over the stereochemical outcome of the cycloaddition was achieved and the structural features of the precursors affecting the stereochemistry is discussed. Useful information was gathered concerning the factors governing this stereocontrol, which will be indispensable for the future of this strategy.Key words: quassinoid, anticancer agent, diene-transmissive DielsAlder cycloaddition, oxadiene, hetero DielsAlder.

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6

Li, Na, Xianrui Liang, and Weike Su. "New insights into the asymmetric Diels–Alder reaction: the endo- and S-selective retro-Diels–Alder reaction." RSC Advances 5, no. 128 (2015): 106234–38. http://dx.doi.org/10.1039/c5ra17788j.

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7

Liu, Hsing-Jang, Wen-Lung Yeh, and Eric N. C. Browne. "Activated cycloheptenone dienophiles. A versatile approach to 6,7-fused ring targets." Canadian Journal of Chemistry 73, no. 7 (July 1, 1995): 1135–47. http://dx.doi.org/10.1139/v95-140.

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Several 2-carbalkoxy-2-cyclohepten-1-ones were prepared and their Diels–Alder characteristics examined in order to develop a facile general approach to the synthesis of cycloheptane ring-containing polycyclic natural products. Substitution pattern on the seven-membered ring was found to greatly affect the Diels–Alder behavior. In addition, some extraordinary facial stereoselectivity was observed. Keywords: Diels–Alder reaction, 2-carbalkoxy-2-cyclohepten-1-ones, 6,7-fused ring system.

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8

Goh, Yit W., and Jonathan M. White. "Structure Correlation Study of Some Diels–Alder Cycloadducts of Anthracene." Australian Journal of Chemistry 62, no. 5 (2009): 419. http://dx.doi.org/10.1071/ch09050.

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Crystal structures of some Diels–Alder cycloadducts of anthracene and a variety of dienophiles reveal structural effects consistent with the manifestation of the early stages of the retro Diels–Alder reaction in the ground state structure. The symmetrical cycloadducts 3 and 4 reveal a qualitative relationship between structure and reactivity, whereas the cycloadducts of 9-methoxyanthracene show structural effects suggestive of the early stages of an asynchronous retro Diels–Alder reaction.

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9

Liu, Zhang, Wang, Zan, and Zhang. "The Role of Iodine Catalyst in the Synthesis of 22-Carbon Tricarboxylic Acid and Its Ester: A Case Study." Catalysts 9, no. 12 (November 20, 2019): 972. http://dx.doi.org/10.3390/catal9120972.

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Here, 22-carbon tricarboxylic acid (C22TA) and its ester (C22TAE) were prepared via the Diels–Alder reaction of polyunsaturated fatty acids (PUFAs) and their esters (PUFAEs) as dienes with fumaric acid (FA) and dimethyl fumarate (DF) as dienophiles, respectively. The role of an iodine catalyst for the synthesis of C22TA and C22TAE in the Diels–Alder type reaction was investigated using a spectroscopic approach. The chemical structures of the products were characterized using proton nuclear magnetic resonance (1H-NMR) and electrospray ionization mass spectrometry (ESI-MS) analysis. Results showed that nonconjugated dienes can react with dienophiles through a Diels–Alder reaction with an iodine catalyst, and that iodine transformed the nonconjugated double bonds of dienes into conjugated double bonds via a radical process. DF was more favorable for the Diels–Alder reaction than FA. This was mainly because the dienophile DF contained an electron-withdrawing substituent, which reduced the highest and lowest occupied molecular orbital (HOMO–LUMO) energy gap and accelerated the Diels–Alder reaction. By transforming nonconjugated double bonds into conjugated double bonds, iodine as a Lewis acid increased the electron-withdrawing effect of the carbonyl group on the carbon–carbon double bond and reduced the energy difference between the HOMO of diene and the LUMO of dienophile, thus facilitating the Diels–Alder reaction.

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10

N'Guyen, Thi Thanh Thuy, Guillaume Contrel, Véronique Montembault, Gilles Dujardin, and Laurent Fontaine. "Phosphonated furan-functionalized poly(ethylene oxide)s using orthogonal click chemistries: synthesis and Diels–Alder reactivity." Polymer Chemistry 6, no. 16 (2015): 3024–30. http://dx.doi.org/10.1039/c5py00188a.

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11

Kirchhof, Susanne, Andrea Strasser, Hans-Joachim Wittmann, Viktoria Messmann, Nadine Hammer, Achim M. Goepferich, and Ferdinand P. Brandl. "New insights into the cross-linking and degradation mechanism of Diels–Alder hydrogels." Journal of Materials Chemistry B 3, no. 3 (2015): 449–57. http://dx.doi.org/10.1039/c4tb01680g.

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12

Yang, Zhongyue, Song Yang, Peiyuan Yu, Yanwei Li, Charles Doubleday, Jiyong Park, Ashay Patel, 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 (January 18, 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 is favored in the enzyme SpnF by both intramolecular hydrogen bonding and hydrophobic binding. Molecular dynamics simulations show that trajectories passing through the ambimodal transition state bifurcate to the [6+4] adduct and the Diels–Alder adduct with a ratio of 1:1 in the gas phase, 1:1.6 in water, and 1:11 in the enzyme. This example shows how an enzyme acts on a vibrational time scale to steer post-transition state trajectories toward the Diels–Alder adduct.

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13

Frank, Scott A., Andrea B. Works, and William R. Roush. "Studies on the synthesis of the decahydro-as-indacene ring system of (-)-spinosyn A via transannular Diels-Alder reactions of substituted (E,E,E)-cyclododeca-1,6,8-trienes." Canadian Journal of Chemistry 78, no. 6 (June 1, 2000): 757–71. http://dx.doi.org/10.1139/v00-045.

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Stereoselective syntheses of decahydro-as-indacenes 31 and 54 are reported. The key features of our syntheses of 31 and 54 are the tandem Ireland-Claisen ring contraction of lactones 29 and 38 followed by the transannular Diels-Alder cyclization of cyclododecatrienes 30 and 35. Transition state modeling of both the transannular Diels-Alder reaction and the Ireland-Claisen ring contraction using PCModel is also described.Key words: transannular Diels-Alder reactions, tandem reactions, Claisen ring contraction, Spinosyn A, synthetic study.

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14

Ayadi, Sameh, and Manef Abderrabba. "Étude DFT des réactions de cycloaddition de type Diels–Alder sur le 4-aza-6-nitrobenzofuroxane." Canadian Journal of Chemistry 85, no. 5 (May 1, 2007): 331–35. http://dx.doi.org/10.1139/v07-026.

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The purpose of this work is a theoretical study of Diels–Alder reactions between the 4-aza-6-nitrobenzofuroxan 1 with a series of dienophiles 3a–3c. From a thermodynamic and orbital point of view, we discuss the reactivity and the stereoselectivty of these reactions. Activation barriers in the Diels-Alder reactions of compound 1 with a series of dienophiles 3a–3c have been calculated and discussed.Key words: inverse electron demand Diels–Alder (IEDDA), DFT method, 4-aza-6-nitrobenzofuroxane.

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15

Wang, Shu-Wen, Wei-Si Guo, Li-Rong Wen, and Ming Li. "A new approach to pyridines through the reactions of methyl ketones with 1,2,4-triazines." RSC Adv. 4, no. 103 (2014): 59218–20. http://dx.doi.org/10.1039/c4ra11294f.

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A new route to prepare pyridine derivatives based on inverse electron demand Diels–Alder/retro-Diels–Alder reactions of ketones with 1,2,4-triazines is reported, which is complementary to the classical Boger reaction.

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16

Jiménez-Estrada, M., R. Reyes-Chilpa, S. Hernández-Ortega, E. Cristobal-Telésforo, L. Torres-Colín, C. K. Jankowski, A. Aumelas, and M. R. Van Calsteren. "Two novel Diels-Alder adducts from Hippocratea celastroides roots and their insecticidal activity." Canadian Journal of Chemistry 78, no. 2 (February 6, 2000): 248–54. http://dx.doi.org/10.1139/v99-239.

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Two novel compounds, celastroidine A (1) and B (2), were isolated from the roots of Hippocratea celastroides K. Their structures were elucidated by spectroscopical and X-ray diffraction studies. Celastroidine A (1) (C50H74O5) was identified as a Diels-Alder adduct of a triterpene plus a diterpene and celastroidine B (2) as a beyerane, a type of dimer of two diterpene (C40H60O4). Both compounds could be formed in vivo by a Diels-Alder reaction. Celastroidine A showed some antifeeding activity against the stored grain insect Sitophyllus zeamays.Key words: Hippocratea celastroides, Hippocrataceae, roots, Diels-Alder adducts, diterpenoids, triterpenoids, x-ray diffraction, insect antifeedants, stored grain insects, Sitophyllus zeamays, insecticidal plants, Diels-Alderase.

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17

Silva, Eduarda, Artur Silva, and Djenisa Rocha. "Diels–Alder Reactions of 1,2-Dihydropyridines: An Efficient Tool for the Synthesis of Isoquinuclidines." Synthesis 50, no. 09 (April 4, 2018): 1773–82. http://dx.doi.org/10.1055/s-0037-1609418.

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The Diels–Alder reaction of 1,2-dihydropyridines with different dienophiles is a well-established and straightforward method for the synthesis of isoquinuclidines. Nevertheless, the enantioselective preparation of isoquinuclidines using organocatalysts or organometallic catalysts is rather unexplored. This succinct review offers readers an overall perspective of the most important recent developments and concepts related to this topic.1 Introduction2 Asymmetric Diels–Alder Reaction of 1,2-Dihydropyridines2.1 Transition-Metal-Catalyzed Reactions2.2 Organocatalyzed Reactions3 Diels–Alder Reaction of 1,2-Dihydropyridines in the Synthesis of Biologically Valuable Compounds4 Conclusion

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18

Gidron, Ori, and Anjan Bedi. "Multiple Diels–Alder Transformations in Linear π-Conjugated Systems." Synlett 30, no. 02 (October 9, 2018): 119–23. http://dx.doi.org/10.1055/s-0037-1610301.

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π-Conjugated molecules are the active materials in organic electronics, yet the range of available materials is limited by the nontrivial, multistep synthetic process required to obtain long π-conjugated backbones. Here, Diels–Alder cycloaddition and its reactivity and selectivity are evaluated as a means for obtaining long, novel, π-conjugated backbones. Particular attention is paid to the Diels–Alder conjugation products of furans, such as selectively substituted arenes and, potentially, carbon nanoribbons.1 Introduction2 Aromatic Transformations by Diels–Alder Cycloaddition3 The Question of Regioselectivity4 Outlook

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19

Ward, Dale E., and Yuanzhu Gai. "Synthesis of 10-methyl-Δ4-octalins by Diels–Alder reactions of 2H-thiopyran surrogates for 1-ethenyl-2-methylcyclohexene." Canadian Journal of Chemistry 75, no. 6 (June 1, 1997): 681–93. http://dx.doi.org/10.1139/v97-082.

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Diels–Alder reactions of 1-ethenyl-2-methylcyclohexene derivatives could be a versatile route to a variety of natural product skeletons that possess a 10-methyldecalin substructure with additional substitution at C-8 and C-9. These dienes are unreactive due (in part) to the presence of the vinyl methyl group, which destabilizes the necessary s-cis conformation. The use of 2H-thiopyran diene surrogates for 1-ethenyl-2-methylcyclohexene is investigated. The desired Diels–Alder adducts were not obtained by reaction of 6,7,8,8a-tetrahydro-5,5-dimethyl-3-tris(1-methylethyl)silyloxy-1H-2-benzothiopyran (7c) or 1,5,7,8-tetrahydrospiro[6H-2-benzothiopyran-6,2′-[1,3]dioxolane] (17) with N-phenylmaleimide. Reactions of 3-[2-(2-methyl-1,3-dioxolan-2-yl)ethyl]-4-[(tris(1-methylethyl)silyl)oxy]-2H-thiopyran (19) with maleimide, N-methylmaleimide, and N-phenylmaleimide under thermal conditions and with N-methylmaleimide, N-phenylmaleimide, 3-(propenoyl)-2-oxazolidinone, and methyl acrylate under Lewis acid mediated conditions (EtAlCl2, TiCl4) gave Diels–Alder adducts in moderate to good yields. In each case, those adducts were readily converted into products that are synthetically equivalent to Diels–Alder adducts of 17 with the same dienophiles. Desulfurization of those products gives 10-methyl-Δ4-octalins (2,3,4,4a,5,6,7,8-octahydro-4a-methylnapthalenes) that are synthetically equivalent to hypothetical Diels–Alder adducts of 1-ethenyl-2-methylcyclohexene-5-one. Keywords: Diels–Alder, 2H-thiopyran, cis-substituted 1,3-diene surrogate, 1-ethenyl-2-methylcyclohexene, octahydro-4a-methylnapthalene derivatives.

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20

Kell, Arnold J., Christopher C. Montcalm, and Mark S. Workentin. "Photogeneration of a diene template for surface DielsAlder reactions: Photoenolization of an ortho-methyl-benzophenone-modified Au cluster." Canadian Journal of Chemistry 81, no. 6 (June 1, 2003): 484–94. http://dx.doi.org/10.1139/v03-031.

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A series of monolayer-protected clusters (MPCs) modified with a photoreactive [4-(11-mercaptoundecyl)-phenyl](2-methylphenyl)methanone (1) moiety have been prepared where 1 is co-absorbed to the MPC surface with dodecanethiol, octadecanethiol, or 11-mercaptoundecanoic acid methyl ester. Upon irradiation the MPC-anchored 1 reacts efficiently through its triplet excited states, yielding 1,4-biradicals that collapse to synthetically useful, long-lived photodienol intermediates, which can be efficiently trapped in DielsAlder type chemistry by dienophiles namely, dimethyl acetylenedicarboxylate (DMAD). In all cases the DielsAlder trapping of the dienol occurred efficiently resulting in >60% conversion to the DielsAlder adduct. This indicates that the local environment surrounding 1 did not influence its ability to react via the DielsAlder reaction; however, the reaction could not be taken to completion. The inability to react completely is attributed to 1 binding to distinct sites on the MPC core; there are edge, vertice, and terrace sites. Selective population of these specific sites and the subsequent irradiations show that MPCs with 1 anchored predominantly at edge and vertice sites results in an extent of reaction of 85 ± 3%, whereas selectively populating the terrace sites results in an extent of reaction of 36 ± 2%. These results suggest that 1 anchored to edge and vertice sites is more reactive to the DielsAlder reaction than that involving terrace sites.Key words: monolayer protected cluster, site selective reactivity, DielsAlder, photochemistry.

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21

Sun, Simin, Chong Teng, and Jiaxi Xu. "Microwave Thermal Effect on Diels-Alder Reaction of Furan and Maleimide." Current Microwave Chemistry 7, no. 1 (June 23, 2020): 67–73. http://dx.doi.org/10.2174/2213335607666200101093318.

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Background: Higher temperature regions (hot spots) have been observed in organic reactions and are attributed to microwave selective heating. The accumulated heat in reaction systems accelerates certain reactions. Methods: The theoretical calculation was applied to select a suitable Diels-Alder reaction as a molecular probe to determine the microwave thermal effect on Diels-Alder reaction, one class of bimolecular reactions. The kinetic investigations were utilized to determine the reaction activation energies and further to calculate the actual reaction temperatures under different microwave conditions from the Arrhenius equation. Results: On the basis of the theoretical calculational results, Diels-Alder reaction of furan and maleimide was selected as a molecular probe to determine the microwave thermal effect in Diels- Alder reaction. Their activation energies under thermal conditions were determined from kinetic data by using the Arrhenius equation. The actual reaction temperatures under different microwave conditions were further deduced from their activation energies and the Arrhenius equation. Conclusion: Higher temperature regions (hot spots) were observed in Diels-Alder reaction, and they are more obvious in less polar solvents than those in more polar solvents in the microwave irradiated reactions.

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22

Breton, Gary W., and Kenneth L. Martin. "Exploring the Limits of Reactivity of N-Methyl-1,2,4-triazoline-3,5-dione (MeTAD) with Disubstituted Bicycloalkadienes in the Homo-Diels–Alder Reaction." Organics 4, no. 1 (December 31, 2022): 41–48. http://dx.doi.org/10.3390/org4010002.

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The [2+2+2] cycloaddition (homo-Diels–Alder reaction) of N-substituted 1,2,4-triazoline-3,5-diones (TADs) with bicycloalkadienes produces strained heterocyclic compounds. A reaction with the unsubstituted dienes occurs readily to produce only the expected homo-Diels–Alder adducts. However, previous work in the literature showed that the attachment of a single electron-withdrawing group to the diene system results in the formation of not only the expected homo-Diels–Alder adducts, but also interesting “insertion” products. To probe the limits of reactivity of these diene systems, we investigated the reaction of N-methyl-1,2,4-triazoline-3,5-dione (MeTAD) with bicycloalkadienes substituted with two electron-withdrawing groups, i.e., two carbomethoxy or two cyano groups. We hoped to learn whether the reaction still proceeded, and if so, whether the homo-Diels–Alder adducts and/or other types of products were formed. We found that a reaction between MeTAD and the dienes takes place upon substitution with two carbomethoxy groups, albeit at a considerably slower rate than other reactions. The only products observed were the homo-Diels–Alder adducts. However, attachment of two CN groups completely inhibited reactivity.

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23

Fedevych, Maria. "α-Unsaturated Acids in Diels-Alder Reaction." Chemistry & Chemical Technology 5, no. 4 (December 15, 2011): 373–75. http://dx.doi.org/10.23939/chcht05.04.373.

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24

Fershtat, Leonid L., Alexander A. Larin, Margarita A. Epishina, Igor V. Ovchinnikov, Alexander S. Kulikov, Ivan V. Ananyev, and Nina N. Makhova. "Design of hybrid heterocyclic systems with a furoxanylpyridine core via tandem hetero-Diels–Alder/retro-Diels–Alder reactions of (1,2,4-triazin-3-yl)furoxans." RSC Advances 6, no. 37 (2016): 31526–39. http://dx.doi.org/10.1039/c6ra05110c.

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Synthetic strategy for the synthesis of hybrid heterocyclic systems with the furoxanylpyridine core based on the tandem hetero-Diels–Alder/retro-Diels–Alder reactions of (1,2,4-triazin-3-yl)furoxans with enamine and norbornadiene has been developed.

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25

Tranmer, Geoffrey K., Carol Yip, Sean Handerson, Robert W. Jordan, and William Tam. "Synthesis of 2,3-disubstituted norbornadienes." Canadian Journal of Chemistry 78, no. 5 (May 1, 2000): 527–35. http://dx.doi.org/10.1139/v00-047.

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Various 2,3-disubstituted norbornadienes that can hardly be made by the traditional Diels-Alder method were synthesized by double lithium halide exchange of 2,3-dibromonorbornadiene in moderate to good yields.Key words: 2,3-disubstituted norbornadienes, Diels-Alder reaction, lithium halide exchange.

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26

Nasir, Shah Bakhtiar, Noorsaadah Abd Rahman, and Chin Fei Chee. "Enantioselective Syntheses of Flavonoid Diels-Alder Natural Products: A Review." Current Organic Synthesis 15, no. 2 (April 24, 2018): 221–29. http://dx.doi.org/10.2174/1570179414666170821120234.

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Background: The Diels-Alder reaction has been widely utilised in the syntheses of biologically important natural products over the years and continues to greatly impact modern synthetic methodology. Recent discovery of chiral organocatalysts, auxiliaries and ligands in organic synthesis has paved the way for their application in Diels-Alder chemistry with the goal to improve efficiency as well as stereochemistry. Objective: The review focuses on asymmetric syntheses of flavonoid Diels-Alder natural products that utilize chiral ligand-Lewis acid complexes through various illustrative examples. Conclusion: It is clear from the review that a significant amount of research has been done investigating various types of catalysts and chiral ligand-Lewis acid complexes for the enantioselective synthesis of flavonoid Diels-Alder natural products. The results have demonstrated improved yield and enantioselectivity. Much emphasis has been placed on the synthesis but important mechanistic work aimed at understanding the enantioselectivity has also been discussed.

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27

Gieling, René G., and Antonius J. H. Klunder. "Immobilized cyclopentadiene in the Diels Alder/retro-Diels Alder concept." Arkivoc 2004, no. 2 (December 19, 2003): 91–108. http://dx.doi.org/10.3998/ark.5550190.0005.207.

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28

Marques, M. Manuel B., Ana M. Lobo, Sundaresan Prabhakar, and Paula S. Branco. "A Diels-Alder, retro-Diels-Alder approach to arcyriaflavin-A." Tetrahedron Letters 40, no. 19 (May 1999): 3795–96. http://dx.doi.org/10.1016/s0040-4039(99)00529-8.

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29

Lemal, David M., Sudharsanam Ramanathan, and John Shellito. "o-Fluoranil Chemistry: Diels–Alder versus Hetero-Diels–Alder Cycloaddition." Journal of Organic Chemistry 73, no. 9 (May 2008): 3392–96. http://dx.doi.org/10.1021/jo7026678.

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30

Jankowski, Christopher K., Gaëtan LeClair, Jacqueline MR Bélanger, Jocelyn RJ Paré, and Marie-Rose VanCalsteren. "Microwave-assisted Diels-Alder synthesis." Canadian Journal of Chemistry 79, no. 12 (December 1, 2001): 1906–9. http://dx.doi.org/10.1139/v01-183.

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The synthesis of isoquinolinone carboxylates was performed using arecoline or its isomer N-methyl tetrahydro pyridine carboxylate with Danishefsky's diene via thermal or microwave assisted Diels-Alder reaction. The comparison of both condensation modes showed that the microwave method not only afforded higher yields of the adducts, but also lead to the formation of a new α,β-unsaturated pyridyl ketone. All structures were identified with the help of high resolution 2D NMR.Key words: Diels-Alder microwave assisted reaction, microwave synthesis, Michael, diene, isoquinoline carboxylate synthesis, Danishefsky diene synthesis, MAP Diels-Alder2.

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31

Rozek, Tomas, Wit Janowski, John M. Hevko, Edward R. T. Tiekink, Suresh Dua, David J. M. Stone, and John H. Bowie. "Syntheses of Angucyclinones Related to Ochromycinone." Australian Journal of Chemistry 51, no. 6 (1998): 515. http://dx.doi.org/10.1071/c97151.

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Two synthetic approaches have been investigated for the syntheses of model angucyclinones related to ochromycinone. The first involves a Diels–Alder/Friedel–Crafts strategy in which the Diels–Alder adduct formed between dimethyl acetylenedicarboxylate and 3-ethenyl-5,5-dimethylcyclohex-2-en-1- one was converted into 6,6-dimethyl-8-oxo-5,6,7,8-tetrahydronaphthalene-1,2-dicarboxylic anhydride, which was then reacted with benzene in a Friedel–Crafts reaction. Acid-catalysed cyclization of the Friedel–Crafts products gave 3,3-dimethyl-3,4-dihydrobenz[a]anthracene-1,7,12(2H)-trione (3) in poor yield. Angucyclinones related to (3) are formed (in 40–50% overall yield) by aromatization of the adduct formed between the appropriate 1,4-naphthoquinone and 3-[(E)-2-methoxyethenyl]- 5,5-dimethylcyclohex-2-en-1-one (this dienone reacts with itself by a Diels–Alder process to yield an adduct which decomposes to 3,3,8,8-tetramethyl-3,4,7,8-tetrahydroanthracene-1,6(2H,5H)-dione). When the substituted 1,4-naphthoquinone is unsymmetrical, a boron triacetate assisted Diels–Alder reaction gives a single regioisomer (e.g. X-ray investigations indicate that 8-hydroxy-3,3-dimethyl-3,4-dihydrobenz[a]anthracene-1,7,12(2H)-trione is the product from 5-hydroxy-1,4-naphthoquinone). An X-ray structural study of the Diels–Alder adduct in the above reaction confirms the operation of an endo cyclization.

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32

Dolci, Elena, Guillaume Michaud, Frédéric Simon, Bernard Boutevin, Stéphane Fouquay, and Sylvain Caillol. "Remendable thermosetting polymers for isocyanate-free adhesives: a preliminary study." Polymer Chemistry 6, no. 45 (2015): 7851–61. http://dx.doi.org/10.1039/c5py01213a.

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Based on a model study, a new bis-cyclic monomer bearing a Diels–Alder adduct was synthesized. This monomer was polymerized with a diamine to yield a thermoresponsive polyhydroxyurethane (PHU). This PHU is remendable at around 100 °C by retro Diels–Alder reaction.

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33

Patel, H. S., and V. C. Patel. "Cross-Linked Polyamides." Polymers and Polymer Composites 10, no. 4 (May 2002): 315–24. http://dx.doi.org/10.1177/096739110201000407.

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Cross linked polyimides containing a s-triazine ring have been synthesized via the Diels-Alder intermolecular polymerization of 2,4,6-tris(2-furanyl methyl imino)-1,3,5-triazine with various bis(maleimide) compounds, followed by the aromatization of the corresponding Diels-Alder products. All the poly(imino- s-triazine imide)s were characterized by elemental analysis, FT-IR spectral studies and thermogravimetry. Glass fibre reinforced composites were prepared via an in-situ Diels-Alder intermolecular reaction between 2,4,6-tris(2-furanyl methyl imino)-1,3,5-triazine and various bis(maleimide) compounds without evolution of by-products. The resulting composites were characterized by mechanical properties.

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34

Zakharova, Daria V., Zalina A. Lok’yaeva, Alexander A. Pavlov, and Alexander V. Polezhaev. "New Chain Extenders for Self-Healing Polymers." Key Engineering Materials 899 (September 8, 2021): 628–37. http://dx.doi.org/10.4028/www.scientific.net/kem.899.628.

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We present here a small series of compounds designed to modify the polymer chain of various polyurethanes in order to introduce a structural fragment with the ability of thermally-triggered reversible covalent interactions. Bismaleimides (2a-2e) were synthesized from commercially available aromatic and aliphatic symmetric diamines (1a-1e) and were further introduced into the Diels-Alder reaction with furfuryl alcohol as dienophiles. The Diels-Alder adducts (3a-3e) were obtained as a mixture of endo- and exo-isomer. The presence of symmetrical hydroxyl groups in the structure of the obtained compounds makes them suitable as chain extenders of low molecular weight diisocyanate prepolymers. The presence of a thermally reversible Diels-Alder reaction adduct in the structure of potential chain-extenders opens a possibility to create unique materials with self-healing properties. All compounds obtained were characterized by 1H, 13C NMR, ESI-HRMS, and IR spectroscopy. The thermochemical parameters of the reverse Diels-Alder reaction were established using DSC analysis.

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35

Rao, Nagaraj. "ASYMMETRIC ORGANOCATALYSIS." INDIAN DRUGS 58, no. 10 (December 16, 2021): 5–6. http://dx.doi.org/10.53879/id.58.10.p0005.

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Dear Reader, Two basic reactions that were taught to us in the organic chemistry courses were the aldol condensation reaction and the Diels-Alder reaction. In aldol condensation, discovered by the French chemist Charles Wurtz in 1872, an enolate ion reacts with a carbonyl compound in the presence of an acid/ base catalyst to form a β-hydroxy aldehyde or a β-hydroxy ketone, usually followed by dehydration to give a conjugated enone. If the enolate ion and the carbonyl group are present in the same molecule, then the aldol reaction is intramolecular. It is an extremely useful carbon-carbon bond-forming reaction. The Diels-Alder reaction, discovered in 1928 by the German chemist Otto Diels and his student Kurt Alder, is the reaction between a conjugated diene and an alkene, a so-called dienophile, to form an unsaturated six-membered ring. It is called a cycloaddition reaction, since the reaction involves the formation of a cyclic product via a cyclic transition state. Uncatalysed Diels– Alder reactions usually require extended reaction times at elevated pressures and temperatures with the formation of by-products, hence various catalysts are employed. The Diels-Alder reaction also has great industrial relevance and the discoverers were crowned with the 1950 Nobel Prize in Chemistry. The aldol condensation reaction and the Diels-Alder reaction typically require catalysts, basically Brønsted acids, Brønsted bases, Lewis acids or Lewis bases. This triggered the minds of Dr. David MacMillan and Dr. Benjamin List for different reasons at different locations in USA around not so different times, more than twenty years ago, culminating in their being jointly awarded the Nobel Prize in Chemistry for this year.

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36

Xia, Qingchun, Yan Liu, Zijian Li, Wei Gong, and Yong Cui. "A Cr(salen)-based metal–organic framework as a versatile catalyst for efficient asymmetric transformations." Chemical Communications 52, no. 89 (2016): 13167–70. http://dx.doi.org/10.1039/c6cc06019f.

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A novel Cr(salen)-based metal–organic framework (MOF) is constructed, which is shown to be a versatile heterogeneous catalyst for a series of important asymmetric transformations including Nazarov cyclization reaction, aminolysis reaction, Diels–Alder and hetero Diels–Alder reactions with the highest ee up to 99%.

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37

Piers, Edward, and Richard W. Friesen. "Synthesis and Diels–Alder reactions of 1-((E)-2-tert-butyldimethylsiloxy)ethylidene-4a-carbomethoxy-1,2,3,4,4a,5,6,7-octahydronaphthalene and related substances. Preparation of functionalized decahydro-1H-phenalenes." Canadian Journal of Chemistry 65, no. 7 (July 1, 1987): 1681–83. http://dx.doi.org/10.1139/v87-281.

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The preparation of the structurally novel dienes 7 and 8 is described. The results of a study of the Diels–Alder reactivity of these substances and the "parent" diene 9 are summarized and the potential use of the resultant Diels–Alder adducts in organic synthesis is demonstrated.

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38

Liu, Hsing-Jang, Dan-Xiong Wang, Jeung Bea Kim, Eric N. C. Browne, and Yu Wang. "Activated cyclooctenones are effective dienophiles." Canadian Journal of Chemistry 75, no. 6 (June 1, 1997): 899–912. http://dx.doi.org/10.1139/v97-108.

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The first Diels–Alder addition of a diene to a cyclooctenone dienophile has been observed. Three activated cyclooctenone dienophiles 1, 2, and 3 are studied with a variety of simple and functionalized dienes. Diels–Alder adducts are produced in excellent yields under very mild Lewis acid catalyzed conditions. The usual orientation rules are followed and, as predicted, the products are formed for the most part exclusively by ester-endo addition. The stereoselectivity is influenced by the substitution pattern of the diene in some cases. The factors influencing the stereochemical selectivity of the addition are discussed in some detail. Keywords: 2-carbalkoxy-2-cyclooctenones, Diels–Alder reaction, six–eight fused ring system.

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39

Srivastava, Vivek. "Ionic-Liquid-Mediated MacMillan’s Catalyst for Diels-Alder Reaction." Journal of Chemistry 2013 (2013): 1–5. http://dx.doi.org/10.1155/2013/954094.

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Ionic liquids were used to enhance as well as recycle the MacMillan's catalyst1for the Diels-Alder reaction. Using our developed protocol, Diels-Alder adducts were obtained in good yields and selectivities along the 6 times recycling of MacMillan's imidazolidinone catalyst1. Synthesis of steroid4is the major outcome of our developed protocol.

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40

Spino, Claude, Laurel Clouston, and David Berg. "Novel, air-stable, lanthanide catalysts for the hetero Diels–Alder reaction." Canadian Journal of Chemistry 74, no. 9 (September 1, 1996): 1762–64. http://dx.doi.org/10.1139/v96-195.

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Novel, air-stable, yttrium and ytterbium complexes were found effective in the catalysis of the typical hetero Diels–Alder reaction of crotonaldehyde and ethylvinyl ether. They represent an attractive solution to the problem of ligand lability in the realm of lanthanide catalysts. Key words: lanthanide, catalyst, hetero Diels–Alder, yttrium, ytterbium.

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41

de la Cruz, Ricardo A., Francisco X. Talamás, Alfredo Vázquez, and Joseph M. Muchowski. "Total synthesis of mycophenolic acid." Canadian Journal of Chemistry 75, no. 6 (June 1, 1997): 641–45. http://dx.doi.org/10.1139/v97-078.

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A total synthesis of mycophenolic acid is reported. Diels–Alder reaction of [5-methoxy-3-(1-methoxypropenyl)-4,5-dihydrofuran-2-yloxy]-trimethylsilane with 3-benzenesulfinyl-5H-furan-2-one afforded the hexasubstituted nucleus. The side chain was constructed from the unveiled aldehyde. Keywords: mycophenolic acid, Diels–Alder reaction, pentasubstituted diene.

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42

Scheerer, Jonathan, Jill Williamson, and Emily Smith. "A Merged Aldol Condensation, Alkene Isomerization, Cycloaddition/Cycloreversion Sequence Employing Oxazinone Intermediates for the Synthesis of Substituted Pyridines." Synlett 28, no. 10 (February 23, 2017): 1170–72. http://dx.doi.org/10.1055/s-0036-1588729.

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A domino reaction sequence has been evaluated that begins with union of novel dihydrooxazinone precursors with 2-alkynyl-substituted benzaldehyde components through aldol condensation. Ensuing operations, including alkene isomerization, Diels–Alder, and retrograde Diels–Alder with loss of CO2 occurs in the same reaction vessel to provide polysubstituted tricyclic pyridine products.

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43

Benmeddah, Amel, Didier Villemin, Bachir Mostefa-Kara, Nathalie Bar, and Remi Legay. "Catalyst-free Diels–Alder reactions of vinylphosphonates with cyclopentadienones." Canadian Journal of Chemistry 95, no. 8 (August 2017): 871–79. http://dx.doi.org/10.1139/cjc-2017-0267.

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The unprecedented thermal Diels–Alder reaction of the diethyl vinylphosphonate and diethyl styrylphosphonate with various cyclopentadienones is described. In these Diels–Alder reactions, catalysis was not required and the corresponding cycloadducts derivatives were obtained. The tetraethyl vinylidene-1,1-bis-phosphonate was found to be less reactive than monophosphonates with the same cyclopentadienones.

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44

Marinier, Anne, Kurt Baettig, Carol Dallaire, Rita Pitteloud, and Pierre Deslongchamps. "Synthesis and transannular Diels–Alder reaction of a cis–trans–trans and a trans–cis–cis 13-membered macrocyclic trienone." Canadian Journal of Chemistry 67, no. 10 (October 1, 1989): 1609–17. http://dx.doi.org/10.1139/v89-246.

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The synthesis of the cis–trans–trans5 and trans–cis–cis6 macrocyclic trienones from cyclohexene is described. Upon heating at 300 °C, trienone 5 underwent 1,5-H shift and transannular Diels–Alder reaction to give adducts 33, 34, and 35 while trienone 6 provided tricyclic ketone 37. Keywords: transannular Diels–Alder reaction.

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45

Carlini, Rina, Kerianne Higgs, Nicholas Taylor, and Russell Rodrigo. "Diels–Alder adducts of ortho-benzoquinones: rearrangements and further transformations." Canadian Journal of Chemistry 75, no. 6 (June 1, 1997): 805–16. http://dx.doi.org/10.1139/v97-097.

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ortho-Benzoquinones substituted with an electron-withdrawing group (EWG = CO2Me, COSMe, COCH3, CHO) at C-3 or C-4 react as dienophiles at the C3—C4 double bond in Diels–Alder reactions with several dienes, with predictable regiochemistry. The adducts undergo migration of the "angular" EWG substituent with concomitant aromatization to produce substituted catechols. The bicyclic products can be oxidized in situ and annelated by a further Diels–Alder reaction to yield 9,10-phenanthraquinone systems. When (2E)-2,4-pentadienol is employed as the diene in the second cycloaddition, reaction of the alcoholic hydroxyl group with one of the quinone carbonyl groups results in the production of tetracyclic lactols 22a, 22b, and 23. Keywords: benzoquinone, Diels–Alder, rearrangement, phenanthraquinone, phenanthrofuran.

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46

Rozek, Tomas, Tomas Rozek, Dennis K. Taylor, Dennis K. Taylor, Edward R. T. Tiekink, Edward R. T. Tiekink, John H. Bowie, and John H. Bowie. "Syntheses of Angucyclinones Related to Ochromycinone. III. An 11-Hydroxy Isomer and Some Reduced Analogues." Australian Journal of Chemistry 52, no. 2 (1999): 129. http://dx.doi.org/10.1071/c98124.

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The boron triacetate assisted Diels Alder reaction between racemic 5,5-dimethyl-3-vinylcyclohex- 2-enyl acetate and 5-hydroxynaphthoquinone yields the racemic 11-hydroxy-3,3-dimethyl-7,12-dioxo- 1,2,3,4,6,6a,7,12,12a,12b-decahydrobenzo[a]anthracen-1-yl acetate as the sole stereoisomer by regio- and stereo-selective cis endo addition. Aromatization of the Diels Alder adduct followed by hydrolysis of the acetate and oxidation of the resultant 1-hydroxy group gives the target angucyclinone, 11-hydroxy-3,3-dimethyl-1,2,3,4,7,12-hexahydrobenzo[a]anthracene-1,7,12-trione, in an overall yield of 37% from 5-hydroxynaphthoquinone. The regio- and stereo-selectivity of the Diels Alder addition is confirmed by a combination of 13C n.m.r. spectroscopy and X-ray crystallography.

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47

Shimizu, Ryo, Yohei Okada, and Kazuhiro Chiba. "Stepwise radical cation Diels–Alder reaction via multiple pathways." Beilstein Journal of Organic Chemistry 14 (March 27, 2018): 704–8. http://dx.doi.org/10.3762/bjoc.14.59.

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Herein we disclose the radical cation Diels–Alder reaction of aryl vinyl ethers by electrocatalysis, which is triggered by an oxidative SET process. The reaction clearly proceeds in a stepwise fashion, which is a rare mechanism in this class. We also found that two distinctive pathways, including “direct” and “indirect”, are possible to construct the Diels–Alder adduct.

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48

Burnell, D. Jean, and Zdenek Valenta. "π-Facial stereoselectivity in the Diels–Alder reactions of a rigid carbocyclic diene: spiro(bicyclo[2.2.1]heptane-2,1′-[2,4]cyclopentadiene)." Canadian Journal of Chemistry 69, no. 1 (January 1, 1991): 179–84. http://dx.doi.org/10.1139/v91-028.

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The plane-nonsymmetrical diene spiro(bicyclo[2.2.1]heptane-2,1′-[2,4]cyclopentadiene) (2) was synthesized, and the π-facial stereoselectivity of its Diels–Alder cycloadditions with three cyclic dienophiles was examined. Adduct ratios were very similar, and the selectivity is surmised to be mainly the result of steric interactions at the transition state. Key words: facial stereoselectivity, Diels–Alder, cycloaddition.

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49

Pla, Paula, Yang Wang, and Manuel Alcamí. "Simple bond patterns predict the stability of Diels–Alder adducts of empty fullerenes." Chemical Communications 54, no. 33 (2018): 4156–59. http://dx.doi.org/10.1039/c8cc01709c.

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A systematic study of Diels–Alder cycloadditions to empty fullerenes reveals that π effects control site preference. Simple Hückel calculation allows to obtain quantitative descriptors and to understand why addition occurs preferentially at certain types of bonds. A couple of simple rules are proposed as a visual guide for a rapid prediction of Diels–Alder reactivity.

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50

He, Siyang, and Guido Kickelbick. "Reversible Diels–Alder Reactions with a Fluorescent Dye on the Surface of Magnetite Nanoparticles." Molecules 26, no. 4 (February 7, 2021): 877. http://dx.doi.org/10.3390/molecules26040877.

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Diels–Alder reactions on the surface of nanoparticles allow a thermoreversible functionalization of the nanosized building blocks. We report the synthesis of well-defined magnetite nanoparticles by thermal decomposition reaction and their functionalization with maleimide groups. Attachment of these dienophiles was realized by the synthesis of organophosphonate coupling agents and a partial ligand exchange of the original carboxylic acid groups. The functionalized iron oxide particles allow a covalent surface attachment of a furfuryl-functionalized rhodamine B dye by a Diels–Alder reaction at 60 °C. The resulting particles showed the typical fluorescence of rhodamine B. The dye can be cleaved off the particle surface by a retro-Diels–Alder reaction. The study showed that organic functions can be thermoreversibly attached onto inorganic nanoparticles.

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