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Journal articles on the topic 'Dienophiles'

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Author: Grafiati

Published: 10 December 2022

Last updated: 19 February 2023

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1

Talma, A. G., R. N. Datta, and J. Aerts. "Quantum Mechanical Calculations to Assess the Antireversion Effects of Several Dienophiles." Rubber Chemistry and Technology 74, no. 4 (September 1, 2001): 574–82. http://dx.doi.org/10.5254/1.3544958.

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Abstract The utilization of Quantum mechanical calculations for substituted dienophiles in the Diels—Alder reaction is very useful in assessing the antireversion effect of various dienophiles. It has been demonstrated that citraconimides provide better antireversion properties than maleimides. A useful explanation is that although maleimides are better dienophiles, they do not survive the vulcanization medium and consequently are not available during the onset of reversion. The antireversion effect of dienophiles varies with the electronic and steric nature of the substituents on the double bond of the dienophile. Calculations are made to demonstrate the effectiveness of various dienophiles in a Diels—Alder reaction. A good correlation has been obtained between the calculations and experimental results.

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2

Omar, Yasser M., Giulia Santucci, and Kamyar Afarinkia. "tert-Butyl(2-oxo-2H-pyran-5-yl)carbamate as the First Chameleon Diene Bearing an Electron-Donating Substituent." Molecules 27, no. 17 (September 2, 2022): 5666. http://dx.doi.org/10.3390/molecules27175666.

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The 2(H)-pyran-2-one bearing electron-donating tert-butylcarbamate (BocNH-) group at the 5- position is a “chameleon” diene and undergoes efficient Diels–Alder cycloadditions with alkene dienophiles with both electron-rich and electron-deficient substituents. Cycloadditions afford the 5-substituted bicyclic lactone cycloadducts regardless of the electronic nature of the dienophile. However, cycloadditions with electronically matched electron-deficient dienophiles proceed faster than those with electronically mismatched electron-rich dienophiles.

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3

Su, Zhishan, and Chan Kyung Kim. "Trienamine catalysis for asymmetric Diels–Alder reactions of 2,4-dienones: a theoretical investigation." Organic & Biomolecular Chemistry 13, no. 22 (2015): 6313–24. http://dx.doi.org/10.1039/c5ob00797f.

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In the Diels–Alder reactions of 2,4-dienones with two dienophiles, cinchona alkaloid acts as an efficient bifunctional catalyst by generating an extended trienamine π-conjugated system and by orienting the dienophile at an appropriate position for a cycloaddition reaction.

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4

Seo, Jeong-Min, and Jong-Beom Baek. "A solvent-free Diels–Alder reaction of graphite into functionalized graphene nanosheets." Chem. Commun. 50, no. 93 (2014): 14651–53. http://dx.doi.org/10.1039/c4cc07173e.

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A solvent-free Diels–Alder reaction between graphite as a diene and a typical dienophile, maleic anhydride or maleimide is developed. The functionalization of graphite with dienophiles is efficient enough for delamination of graphitic layers into graphene nanosheets upon dispersion in a polar solvent.

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5

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 (July 1, 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 cyclized readily. With an (E)-enoate as the dienophile, the stereoselectivity was poor (endo:exo = 1.1–2.5:1) and essentially independent of reaction conditions (i.e., thermal vs. Lewis acid mediated). With the(Z)-enoate, a 7:1 mixture of endo:exo IMDA adducts was obtained under thermal conditions; with Lewis acid catalysis, isomerization of the dienophile was competitive with cycloaddition. Type II IMDA adducts were not observed with C-5 tethered substrates. Compounds having the dienophile attached to C-6 via a C3 or a five-atom tether also failed to give IMDA adducts. No evidence for isomerization of the 2H-thiopyran dienes by [1,5] sigmatropic rearrangement was observed. The endo adducts from IMDA reactions of the C-3 tethered substrates can be desulfurized to obtain synthetically useful trans-fused hydrindans and decalins with angular methyl groups. Key words: intramolecular Diels–Alder, 2H-thiopyran, cis-substituted 1,3-diene surrogate, trans-octahydro-3a-methyl-1H-indene derivatives, trans-decahydro-4a-methylnapthalene derivatives.

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6

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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7

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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8

Ndibwami, Alexis, Serge Lamothe, Daniel Guay, Raymond Plante, Pierre Soucy, Solo Goldstein, and Pierre Deslongchamps. "Transannular Diels–Alder reactions on 14-membered macrocyclic trienes. Part I: stereoselective syntheses of the macrocyclic trienes precursors." Canadian Journal of Chemistry 71, no. 5 (May 1, 1993): 695–713. http://dx.doi.org/10.1139/v93-094.

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Transannular Diels–Alder reactions on 14-membered macrocycles containing properly located diene and methyl-substituted dienophile units lead to A.B.C.[6.6.6] tricycles related to steroids. To study the influence of the olefin and diene geometry on the stereochemical outcome of the Diels–Alder reaction it was necessary to prepare macrocyclic trienes of well-defined stereochemistry. Eight different types of macrocyclic trienes might be obtained by the coupling of appropriate dienophiles and dienes, namely, TTC, TTT, TCC, TCT, CTC, CTT, CCC, and CCT. In this paper (first in a series of two), the synthesis of appropriately functionalized dienophile and diene synthons, as well as their coupling reaction affording macrocyclic triene precursors, is described.

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9

Barta, Petra, Ferenc Fülöp, and István Szatmári. "Mannich base-connected syntheses mediated by ortho-quinone methides." Beilstein Journal of Organic Chemistry 14 (March 6, 2018): 560–75. http://dx.doi.org/10.3762/bjoc.14.43.

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This article provides an overview about specifically modified Mannich reactions where the process involves an ortho-quinone methide (o-QM) intermediate. The reactions are classified on the basis of the o-QM source followed by the reactant, e.g., the dienophile partner in cycloaddition reactions (C=C or C=N dienophiles) or by the formation of multicomponent Mannich adducts. Due to the important pharmacological activities of these reactive o-QM intermediates, special attention is paid to the biological activity of these compounds.

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10

Thiessen, Merlina, and Volker Abetz. "Influence of the Glass Transition Temperature and the Density of Crosslinking Groups on the Reversibility of Diels-Alder Polymer Networks." Polymers 13, no. 8 (April 7, 2021): 1189. http://dx.doi.org/10.3390/polym13081189.

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The interest in self-healing, recyclable, and adaptable polymers is growing. This work addresses the reversibility of crosslink formation based on Diels-Alder reaction in copolymer networks containing furfuryl and maleimide groups, which represent the “diene” and the “dienophile,” respectively. The copolymers are synthesized by atom transfer radical polymerization (ATRP) and free radical polymerization. The diene bearing copolymers are crosslinked either with a small molecule containing two dienophiles or with a dienophile bearing copolymer. The influence of the crosslinking temperature on the Diels-Alder reaction is analyzed. Furthermore, the influence of the glass transition temperature and the influence of the density of crosslinking groups on the thermo-reversibility of crosslinking are investigated by temperature dependent infrared spectroscopy and differential scanning calorimetry. It is shown that the reversibility of crosslinking is strongly influenced by the glass transition temperature of the system.

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11

Laue, Jörg, Gunther Seitz, and Hans Waßmuth. "Synthese und [4+2]-Cycloadditionen von 4a, 8a-Methanophthalazin, das erste Propellan mit einem elektronenreichen und einem elektronenarmen 4π-Diensystem/Synthesis and [4+2] Cycloaddition Reactions of 4a, 8a-Methanophthalazine, the First Propellane with an Electronrich and an Electrondeficient 4π-Diene System." Zeitschrift für Naturforschung B 51, no. 3 (March 1, 1996): 348–58. http://dx.doi.org/10.1515/znb-1996-0309.

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Abstract Cyclopropabenzene 3 reacts with 3,6-bis(trifluoro)-1,2,4,5-tetrazine 4 to afford in high yield the 4a,8a-methanophthalazine 6, the first propellane, containing an electron rich cyclohexadiene system on the one hand and an electron deficient diazadiene system on the other hand. According to the principle of Diels-Alder reactions with inverse electron demand, electron rich dienophiles like ketene acetals, enamines or dimethyl hydrazones react predominantly with the diazadiene system to yield the azo-bridged cycoadducts of type 19 and/or the tricyclic tetrahydropyridazines like 20. In the same fashion several more or less angle strained cycloalkenes cycloadd to the diazadiene of the propellane 6 to give the novel polycyclic azo compounds 34, 36, 38,40, 42 and 44 with exo-configuration of the annulated cycloalkanes. Attack apparently occurs from less hindered face anti to the methano bridge of 6 with high stereo-and site-selectivity. As anticipated the electron deficient dienophiles 1,2,4-triazoline-3,5-dione 45 and the benzoquinone 46 add with different site selectiviy to 6 furnishing the polycyclic pyridazines 47 and 48 resp. again by exclusive anti attack. Treatment of 6 with both an electron rich and an electron deficient dienophile like 49 and 45 resp. affords the heptacyclic anti-anti-bis adduct 51 with analogously high site-and stereoselectivity.

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12

Beig, Nosheen, Aarti Peswani, and Raj Kumar Bansal. "Dienophilic reactivity of 2-phosphaindolizines: a conceptual DFT investigation." Beilstein Journal of Organic Chemistry 18 (September 13, 2022): 1217–24. http://dx.doi.org/10.3762/bjoc.18.127.

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The >C=P– or –N=P– functionality in 1,3-azaphospholo[1,5-a]pyridine, named as 2-phosphaindolizine and its 1- and 3-aza derivatives act as dienophiles and undergo Diels–Alder reactions with 1,3-dienes. However, the dienophilic reactivity is affected by the nature of the substituent groups on the two sides of the σ2,λ3-P atom and also by the presence of more nitrogen atom(s) in the five-membered ring. The conceptual density functional theory (DFT) calculations have been used in recent years to predict the reactivity of organic molecules in reactions. We calculated global hardness (η), global softness (S), electronic chemical potential (μ), electrophilicity (ω), and nucleophilicity (N) indices of four classes of 2-phosphaindolizines, on the basis of which their observed relative dienophilic reactivities could be rationalized. Besides, the Fukui functions of the carbon/nitrogen and phosphorus atoms of the >C=P– and –N=P– functionalities were also computed which revealed their hard electrophilic character and accorded well with the dienophilic reactivities observed experimentally. Furthermore, energies and symmetries of the lowest unoccupied molecular orbitals (LUMO) of 2-phosphaindolizines were found to be in conformity with their dienophilic reactivities.

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13

Kurpanik, Aneta, Marek Matussek, Piotr Lodowski, Grażyna Szafraniec-Gorol, Michał Krompiec, and Stanisław Krompiec. "Diels–Alder Cycloaddition to the Bay Region of Perylene and Its Derivatives as an Attractive Strategy for PAH Core Expansion: Theoretical and Practical Aspects." Molecules 25, no. 22 (November 17, 2020): 5373. http://dx.doi.org/10.3390/molecules25225373.

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PAHs (polycyclic aromatics hydrocarbons), the compound group that contains perylene and its derivatives, including functionalized ones, have attracted a great deal of interest in many fields of science and modern technology. This review presents all of the research devoted to modifications of PAHs that are realized via the Diels–Alder (DA) cycloaddition of various dienophiles to the bay regions of PAHs, leading to the π-extension of the starting molecule. This type of annulative π-extension (APEX) strategy has emerged as a powerful and efficient synthetic method for the construction of polycyclic aromatic hydrocarbons and their functionalized derivatives, nanographenes, and π-extended fused heteroarenes. Then, [4 + 2] cycloadditions of ethylenic dienophiles, -N=N-, i.e., diazo-dienophiles and acetylenic dienophiles, are presented. This subject is discussed from the organic synthesis point of view but supported by theoretical calculations. The possible applications of DA cycloaddition to PAH bay regions in various science and technology areas, and the prospects for the development of this synthetic method, are also discussed.

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14

Ma, Zhiyuan, Feng Ni, Grace H. C. Woo, Sie-Mun Lo, Philip M. Roveto, Scott E. Schaus, and John K. Snyder. "An intramolecular inverse electron demand Diels–Alder approach to annulated α-carbolines." Beilstein Journal of Organic Chemistry 8 (June 6, 2012): 829–40. http://dx.doi.org/10.3762/bjoc.8.93.

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Intramolecular inverse electron demand cycloadditions of isatin-derived 1,2,4-triazines with acetylenic dienophiles tethered by amidations or transesterifications proceed in excellent yields to produce lactam- or lactone-fused α-carbolines. Beginning with various isatins and alkynyl dienophiles, a pilot-scale library of eighty-eight α-carbolines was prepared by using this robust methodology for biological evaluation.

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15

Welker, Mark E. "Boron and Silicon-Substituted 1,3-Dienes and Dienophiles and Their Use in Diels-Alder Reactions." Molecules 25, no. 16 (August 16, 2020): 3740. http://dx.doi.org/10.3390/molecules25163740.

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Boron and silicon-substituted 1,3-dienes and boron and silicon-substituted alkenes and alkynes have been known for years and the last 10 years have seen a number of new reports of their preparation and use in Diels-Alder reactions. This review first covers boron-substituted dienes and dienophiles and then moves on to discuss silicon-substituted dienes and dienophiles.

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16

Wei, Hong Liang, Ya Li Feng, Hui Juan Chu, and Kai Yao. "Fabrication of Supramolecular Structured Hydrogels Based on Diels-Alder Click Reaction." Advanced Materials Research 562-564 (August 2012): 405–8. http://dx.doi.org/10.4028/www.scientific.net/amr.562-564.405.

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A novel kind of supramolecular structrued hydrogels were fabricated by Diels-Alder click reaction between furan-functionalized polypseudorotaxanes and polymeric dienophiles. Firstly, polypseudorotaxanes were prepared by supramolecular self-assembly of furan-terminated poly(ethylene glycol)(PEG) and α-cyclodextrins (CDs) in water. And polymeric dienophiles were synthesized by a coupling reaction between copolymer of hydroxyethyl methacrylate and N,N-dimethyl acrylamide and N-maleoyl alanine (AMI). The supramolecular structured hydrogels were prepared by Diels-Alder reaction in water.

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17

Ward, Dale E., and Yuanzhu Gai. "Lewis acid mediated Diels–Alder reactions of 2H-thiopyrans." Canadian Journal of Chemistry 70, no. 10 (October 1, 1992): 2627–34. http://dx.doi.org/10.1139/v92-331.

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Lewis acid mediated Diels–Alder reactions of 2H-thiopyrans with acrylate, crotonate, and methacrylate dienophiles have been investigated. Modest to good yields of predominantly exo adducts are obtained with 4-substituted 2H-thiopyrans. With 5-substituted 2H-thiopyrans, high endo selectivity is observed. No adducts were produced with methacrylate dienophiles. Relative to the thermal reactions, the exo selectivity is enhanced in the presence of Lewis acids. Unusually high exo selectivity is observed using "wet" Et2AlCl as the promoter.

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18

Piers, Edward, Richard W. Friesen, Paul Kao, Steven J. Rettig, and James Trotter. "Synthesis of functionalized hexahydro-, octahydro-, and decahydro-1H-phenalenes via Diels–Alder reactions of 1-methylene-4a-methoxycarbonyl-1,2,3,4,4a,5,6,7-octahydronaphthalene and related dienes." Canadian Journal of Chemistry 71, no. 9 (September 1, 1993): 1463–83. http://dx.doi.org/10.1139/v93-188.

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The results of a study of Diels–Alder reactions of the bicyclic dienes 6–8 with a variety of dienophiles are reported. Although 6 and 7 undergo cycloaddition reactions smoothly and efficiently, thermal Diels–Alder reactions of 8 are generally sluggish or, under the conditions investigated, do not proceed at all. Additions of tetracyanoethylene (TCNE) to 6–8 are highly face-selective, with preferential attack of the dienophile on the side of the dienes opposite to the angular methoxycarbonyl group. Reaction of 7 with maleic anhydride (MAN) is completely face-selective and proceeds preferentially via an endo transition state. Diels–Alder reactions of 6 and 7 with methyl acrylate (MAC) and nitroethylene (NE) are entirely regioselective, but the face-selectivities, which vary from ~2:1 to ~3:1, are rather low. The use of this chemistry as a method for the synthesis of functionalized, stereochemically defined, perhydro-1H-phenalenes is demonstrated.

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19

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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20

Liang, Zhiling, Houhe Liu, Nianjun Su, Dandan Song, Yun Zhang, Hong Huang, Jianqi Zheng, Cheng Zhong, and Guodong Ye. "Study of the Deformation/Interaction Model: How Interactions Increase the Reaction Barrier." Journal of Chemistry 2018 (2018): 1–8. http://dx.doi.org/10.1155/2018/3106297.

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The interactions (including weak interactions) between dienophiles and dienes play an important role in the Diels-Alder reaction. To elucidate the influence of these interactions on the reactivity, a popular DFT functional and a variational DFT functional corrected with dispersion terms are used to investigate different substituent groups incorporated on the dienophiles and dienes. The bond order is used to track the trajectory of the cycloaddition reaction. The deformation/interaction model is used to obtain the interaction energy from the reactant complex to the inflection point until reaching the saddle point. The interaction energy initially increases with a decrease in the interatomic distance, reaching a maximum value, but then decreases when the dienophiles and dienes come closer. Reduced density gradient and chemical energy component analysis are used to analyse the interaction. Traditional transition state theory and variational transition state theory are used to obtain the reaction rates. The influence of tunneling on the reaction rate is also discussed.

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21

Sultan, Mujeeb A., Mansour S. A. Galil, Mohyeddine Al-Qubati, Mufeed M. Omar, and Assem Barakat. "Synthesis, Molecular Docking, Druglikeness Analysis, and ADMET Prediction of the Chlorinated Ethanoanthracene Derivatives as Possible Antidepressant Agents." Applied Sciences 10, no. 21 (October 31, 2020): 7727. http://dx.doi.org/10.3390/app10217727.

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Ethanoanthracene cycloadducts (5–7) anti, (5–7) syn, and (5–7) dec have been synthesized from the Diels–Alder (DA) reaction of diene 1,8-dichloroanthracene 2, with the dienophiles; acrylonitrile 3, 1-cynavinyl acetate 4, and phenyl vinyl sulfone 5, individually. The steric effect of dienophile substituents were more favorable toward the anti-isomer formation as deduced from 1H-NMR spectrum. The cheminformatics prediction for (5–7) anti and (5–7) syn was investigated. The in silico anticipated anti-depression activity of the (5–7) anti and (5–7) syn compounds were investigated and compared to maprotiline 9 as reference anti-depressant drug. The study showed that steric interactions play a crucial role in the binding affinity of these compounds to the representative models; 4xnx, 2QJU, and 3GWU. The pharmacokinetic and drug-like properties of (5–7) anti and (5–7) syn exhibited that these compounds could be represented as potential candidates for further development into antidepressant-like agents.

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22

Rogers, Christine, and Brian A. Keay. "The effect of Lewis acids on the intramolecular Diels–Alder reaction of the furan diene." Canadian Journal of Chemistry 70, no. 12 (December 1, 1992): 2929–47. http://dx.doi.org/10.1139/v92-375.

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A general method is described for effecting the intramolecular Diels–Alder reaction of the furan diene in which the side arm connecting the diene to the dienophile contains four carbon atoms. The use of 1.1 equivalents of methylaluminum dichloride at −78 °C for 2–8 h shifts the Diels–Alder equilibrium towards the products and provides the oxatricyclo adducts in good to excellent yield. Catalytic quantities of methylaluminum dichloride (10 mol%) provided a higher quantity of adduct than excess Lewis acid when the enone was substituted with alkyl groups. The scope was extended to include a precursor containing a five carbon atom side arm, and two examples containing acetylenic dienophiles that were activated by a carbonyl moiety on the side arm. Precursors having a four carbon atom side arm provided only oxatricyclo adducts having the side arm syn to the oxygen bridge. The assignment of the stereochemistry of the oxatricyclo adducts is discussed in detail.

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23

Lee, Jennifer J., and George A. Kraus. "One-pot formal synthesis of biorenewable terephthalic acid from methyl coumalate and methyl pyruvate." Green Chem. 16, no. 4 (2014): 2111–16. http://dx.doi.org/10.1039/c3gc42487a.

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24

Borisevich, Sophia S., Alena V. Kovalskaya, Inna P. Tsypysheva, and Sergey L. Khursan. "Thermodynamically controlled Diels–Alder reaction of 12-N-methylcytisine: A DFT study." Journal of Theoretical and Computational Chemistry 13, no. 06 (September 2014): 1450048. http://dx.doi.org/10.1142/s0219633614500485.

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A DFT study was performed for the Diels–Alder traction of 12-N-methylcytisine with a number of dienophiles (in boiling toluene under atmospheric pressure), namely, N-phenylmaleimide, maleic anhydride, 2,4-benzoquinone, tetracyanoethylene and methyl methacrylate. It was shown that 12-N-methylcytisine selectively reacts with these dienophiles, only the reaction with N-phenylmaleimide (NPM) resulting in the formation of thermodynamically stable adducts, which is consistent with experimental data. This selectivity of 12-N-methylcytisine is attributable to the difference between the properties of the listed dienophiles, which is confirmed by the relative reactivity indices calculated within the framework of the frontier molecular orbital (FMO) and hard and soft (Lewis) acids and bases (HSAB) theories, the thermodynamic and activation parameters of the forward and retro-Diels–Alder reactions. According to analysis of the theoretical results, NPM is characterized by high chemical potential, hardness close to that of 12-N-methylcytisine, and commensurable heights of the activation barriers for the forward and reverse Diels–Alder reactions and also forms stable [4+2] adducts.

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25

Rogers, Christine, and Brian A. Keay. "Diastereoselective intramolecular Diels–Alder reactions of the furan diene: the synthesis of (±)-1,4-epoxycadinane." Canadian Journal of Chemistry 71, no. 5 (May 1, 1993): 611–22. http://dx.doi.org/10.1139/v93-081.

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The diastereoselective intramolecular Diels–Alder reactions of the furan diene (IMDAF), in which the side arm comprises four carbon atoms and is substituted by a methyl group adjacent to, or one carbon removed from, the furan ring, are described. Adducts are formed in moderate to excellent yields when treated with either Florisil in methylene chloride at room temperature or methylaluminum dichloride in methylene chloride at −78 °C. Florisil is most effective for substrates containing unsubstituted dienophiles. An equimolar quantity (1.1 equivalents) of methylaluminum dichloride is most effective for precursors having methacrolein-type dienophiles, while a catalytic quantity (0.1 equivalent) is effective for crotonaldehyde-type dienophiles. Only the adducts with the side arm orientated syn with respect to the oxygen bridge are detected and isolated. The major diastereomer is the one in which the methyl group (initially on the side arm) is situated equatorially on the newly formed six-membered ring. An application of the diastereoselective IMDAF reaction to the synthesis of (±)-1,4-epoxycadinane is described, beginning with 2-methylfuran.

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26

Paredes, Elisa, Betina Biolatto, Marı́a Kneeteman, and Pedro M. Mancini. "Nitronaphthalenes as Diels–Alder dienophiles." Tetrahedron Letters 41, no. 42 (October 2000): 8079–82. http://dx.doi.org/10.1016/s0040-4039(00)01436-2.

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27

Adam, Waldemar, Metin Balci, Zeynep Ceylan, and Ricardo Francisco Hinz. "Reactions of Benzocycloheptenes with Dienophiles." Chemische Berichte 124, no. 2 (February 1991): 383–86. http://dx.doi.org/10.1002/cber.19911240222.

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28

Ward, Dale E., Yuanzhu Gai, and Wajdi M. Zoghaib. "Diels–Alder reactions of activated 2H-thiopyrans." Canadian Journal of Chemistry 69, no. 10 (October 1, 1991): 1487–97. http://dx.doi.org/10.1139/v91-220.

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The Diels–Alder reactivity of various 2H-thiopyrans bearing electron-donating substituents has been investigated. The approximate order of reactivity among the 2H-thiopyrans studied was 4,6-disubstituted [Formula: see text] 5-substituted > 4-substituted, 3,5-disubstituted [Formula: see text] 3-substituted. Good yields of predominantly endo adducts are obtained with reactive dienophiles. With less reactive dienophiles, reactions are much slower and yields are attenuated due to the competing thermal decomposition of the dienes under the reaction conditions. The adducts obtained are equivalent (via desulfurization) to those from unreactive cis-substituted dienes. Key words: Diels–Alder, 2H-thiopyran.

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29

Bornadiego, Ana, Jesús Díaz, and Carlos F. Marcos. "Tandem synthesis of 4-aminoxanthones is controlled by a water-assisted tautomerization: a general straightforward reaction." Organic & Biomolecular Chemistry 17, no. 6 (2019): 1410–22. http://dx.doi.org/10.1039/c8ob02527d.

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30

Abbasov, Mikail E., Brandi M. Hudson, Weixu Kong, Dean J. Tantillo, and Daniel Romo. "Enantioselective Diels-Alder-lactamization organocascades employing a furan-based diene." Organic & Biomolecular Chemistry 15, no. 15 (2017): 3179–83. http://dx.doi.org/10.1039/c6ob02738e.

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31

Lording, William J., Thomas Fallon, Michael S. Sherburn, and Michael N. Paddon-Row. "The simplest Diels–Alder reactions are not endo-selective." Chemical Science 11, no. 43 (2020): 11915–26. http://dx.doi.org/10.1039/d0sc04553e.

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32

Billaud, Emilie M. F., Elnaz Shahbazali, Muneer Ahamed, Frederik Cleeren, Timothy Noël, Michel Koole, Alfons Verbruggen, Volker Hessel, and Guy Bormans. "Micro-flow photosynthesis of new dienophiles for inverse-electron-demand Diels–Alder reactions. Potential applications for pretargeted in vivo PET imaging." Chemical Science 8, no. 2 (2017): 1251–58. http://dx.doi.org/10.1039/c6sc02933g.

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33

Huang, Ci-Jhang, and Elise Y. Li. "Molecular design principles towards exo-exclusive Diels–Alder reactions." RSC Advances 9, no. 13 (2019): 7246–50. http://dx.doi.org/10.1039/c8ra10438g.

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34

Kaur, Jasneet, Pankaj Chauhan, and Swapandeep Singh Chimni. "α,α-Dicyanoolefins: versatile substrates in organocatalytic asymmetric transformations." Organic & Biomolecular Chemistry 14, no. 33 (2016): 7832–47. http://dx.doi.org/10.1039/c6ob01229a.

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35

Zhu, Jun, Stephen Li, Carmen Wängler, Björn Wängler, R. Bruce Lennox, and Ralf Schirrmacher. "Synthesis of 3-chloro-6-((4-(di-tert-butyl[18F]fluorosilyl)-benzyl)oxy)-1,2,4,5-tetrazine ([18F]SiFA-OTz) for rapid tetrazine-based18F-radiolabeling." Chemical Communications 51, no. 62 (2015): 12415–18. http://dx.doi.org/10.1039/c5cc03623b.

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36

Abbasov, Mikail E., Brandi M. Hudson, Dean J. Tantillo, and Daniel Romo. "Stereodivergent, Diels–Alder-initiated organocascades employing α,β-unsaturated acylammonium salts: scope, mechanism, and application." Chemical Science 8, no. 2 (2017): 1511–24. http://dx.doi.org/10.1039/c6sc04273b.

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37

Koner, Abhishek, Bulat M. Gabidullin, Zsolt Kelemen, László Nyulászi, Georgii I. Nikonov, and Rainer Streubel. "7-Metalla-1,4-diphosphanorbornadienes: cycloaddition of monovalent group 13 NacNac complexes to a stable 1,4-diphosphinine." Dalton Transactions 48, no. 23 (2019): 8248–53. http://dx.doi.org/10.1039/c9dt01425j.

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Monovalent group 13 NacNac complexes reacted as dienophiles with a tricyclic 1,4-diphosphinine to furnish first examples of 7-metalla-1,4-diphosphanorbornadienes via reversible [4 + 1]-cycloaddition reactions.

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38

Itoh, Takashi, Akio Ohsawa, Mamiko Okada, Terumitsu Kaihoh, and Hiroshi Igeta. "Reaction of 1,2,3-triazine with dienophiles." CHEMICAL & PHARMACEUTICAL BULLETIN 33, no. 7 (1985): 3050–52. http://dx.doi.org/10.1248/cpb.33.3050.

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39

Williams, D. R., and R. D. Gaston. "Intramolecular cycloadditions using vinyl sulfide dienophiles." Tetrahedron Letters 27, no. 13 (January 1986): 1485–88. http://dx.doi.org/10.1016/s0040-4039(00)84291-4.

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40

Blades, Kevin, Thierry P. Lequeux, and Jonathan M. Percy. "Reactive dienophiles containing a difluoromethylenephosphonato group." Chemical Communications, no. 12 (1996): 1457. http://dx.doi.org/10.1039/cc9960001457.

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41

Riviere, Pierre, Antony Mauvais, and Ekkehard Winterfeldt. "Pure enantiomers from simple, symmetric dienophiles." Tetrahedron: Asymmetry 5, no. 9 (September 1994): 1831–46. http://dx.doi.org/10.1016/0957-4166(94)80092-8.

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42

Davis, Anna E., Jared M. Lowe, and Michael K. Hilinski. "Vinylazaarenes as dienophiles in Lewis acid-promoted Diels–Alder reactions." Chemical Science 12, no. 48 (2021): 15947–52. http://dx.doi.org/10.1039/d1sc05095h.

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Vinyl-substituted azaarenes are rare and challenging substrates as dienophiles in Diels–Alder reactions; by employing Lewis acid activation, high yielding and highly selective cycloadditions with unactivated dienes are enabled.

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43

Ferreira, Juliana, Vera C. M. Duarte, Jennifer Noro, António Gil Fortes, and Maria J. Alves. "Total facial selectivity of a d-erythrosyl aromatic imine in [4π + 2π] cycloadditions; synthesis of 2-alkylpolyol 1,2,3,4-tetrahydroquinolines." Organic & Biomolecular Chemistry 14, no. 10 (2016): 2930–37. http://dx.doi.org/10.1039/c5ob02594j.

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Different electron-rich dienophiles were combined with the imine obtained from 2,4-O-benzylidene-d-erythrose and p-anisidine furnishing enantiomerically pure tetrahydroquinolines, by inverse electron-demand [4π + 2π] cycloaddition.

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44

Shimizu, Makoto, Toshihiro Yamamoto, Hiroaki Shindo, Isao Mizota, and Yusong Zhu. "2,3-Dimethoxy-2,3-dimethyl-1,4-dioxane as a useful precursor to 2,3-dimethylene-1,4-dioxane for [4+2] cycloaddition reaction." RSC Advances 11, no. 14 (2021): 7972–80. http://dx.doi.org/10.1039/d1ra00329a.

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2,3-Dimethoxy-2,3-dimethyl-1,4-dioxane serves as a stable precursor to 2,3-dimethylene-1,4-dioxane which undergoes a cycloaddition with dienophiles. The adducts are transformed into useful intermediates for biologically important materials.

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45

Yamada, S., K. Hondo, T. Konno, and T. Ishihara. "Concise preparation of fluorine-containing carbocycles involving the Diels–Alder reaction using fluorinated alkene or diene derivatives." RSC Advances 6, no. 34 (2016): 28458–69. http://dx.doi.org/10.1039/c6ra00569a.

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The Diels–Alder reactions of trifluorovinyl substances with various dienes or 2,3-difluorobuta-1,3-dienes with various dienophiles proceeded well to give the corresponding trifluorinated cyclohexenes or vic-difluorocyclohexenes in acceptable yields, respectively.

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46

Ameta, Sandeep, Juliane Becker, and Andres Jäschke. "RNA–peptide conjugate synthesis by inverse-electron demand Diels–Alder reaction." Org. Biomol. Chem. 12, no. 26 (2014): 4701–7. http://dx.doi.org/10.1039/c4ob00076e.

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We present an efficient method to synthesize RNA–peptide conjugates employing inverse Diels–Alder cycloaddition. Different dienophiles are enzymatically incorporated into RNA and then conjugated with a tetrazine peptide at 1 : 1 stoichiometry.

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47

Schnierle, Marc, Svenja Blickle, Vasileios Filippou, and Mark R. Ringenberg. "Tetrazine metallation boosts rate and regioselectivity of inverse electron demand Diels–Alder (iEDDA) addition of dienophiles." Chemical Communications 56, no. 80 (2020): 12033–36. http://dx.doi.org/10.1039/d0cc03805a.

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Reported herein is the coordination of rhenium complexes to tetrazine ligand in [ReCl(CO)₃(TzPy)] [1] (TzPy = 3-(2-pyridyl)-1,2,4,5-tetrazine) and the rates of addition of different dienophiles to the tetrazine.

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48

Langlois, Yves. "New Uses of Oxazolines, Oxazoline N-Oxides and Dioxolanyliums in Asymmetric Synthesis." Current Organic Chemistry 2, no. 1 (January 1998): 1–18. http://dx.doi.org/10.2174/1385272802666220126210228.

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Camphor-substituted 2-alkenyl oxazolines, after acylation with trifluoroacetic anhydride, are useful dienophiles in various low temperature Diels-Aider cycloadditions. These reactions are highly stereoselective not only with classical carbodienes but also with functionalized dienes such as diene enolphosphates and 1,2-dihydropyridines. In this example, the resulting adduct has been used in a new synthetic approach of the south part of antibiotics Avermectins. An other type of asymmetric cationic Diels-Aider cycloaddition has been studied using the reactive 2-alkenyl dioxolanylium cations as dienophiles. The influence of electronic and steric factors upon the stereoselectivity were examined. Finally camphor derived oxazoline N-oxides proved to be very useful dipolarophiles in a new kind of asymmetric [2+3] cycloaddition. The resulting adducts have been transformed into various enantiomerically pure compounds, such as -hydroxyketone, spiroketalic pheromone, carbonucleoside, lactone and -hydroxy-a-alkyl a-amino acids.

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49

Kvyatkovskaya, Elizaveta A., Polina P. Epifanova, Eugeniya V. Nikitina, Aleksey A. Senin, Victor N. Khrustalev, Kirill B. Polyanskii, and Fedor I. Zubkov. "Synthesis and ethylene-promoted metathesis of adducts of tandem [4+2]/[4+2] cycloaddition between bis-furyl dienes and maleic acid derivatives." New Journal of Chemistry 45, no. 7 (2021): 3400–3407. http://dx.doi.org/10.1039/d0nj04528d.

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A series of 1,4:5,8-diepoxynaphthalenes, annellated with carbo- and heterocycles, was synthesized based on the tandem intermolecular/intramolecular [4+2] cycloaddition of bis-furyl dienes with moderately to highly reactive cyclic dienophiles (maleic anhydride and maleinimides).

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50

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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