Microwave-assisted reactions of nitroheterocycles with dienes. Diels-Alder and tandem hetero Diels-Alder/[3,3] sigmatropic shift

Author: Victoria Gómez, M.; Aranda, A.I.; Moreno, A.; Cossío, F.P.; de Cózar, A.; Díaz-Ortiz, Á.; de la Hoz, A.; Prieto, P. Description: Diels-Alder cycloaddition of 3-nitro-1-(p-toluenesulfonyl)indole 1 with dienes 2-6 under microwave irradiation in solvent-free conditions gave carbazole derivatives after elimination of the nitro group and in situ aromatization. While 3-nitro-1-(p-toluenesulfonyl)pyrrole 11 afforded indole derivatives, 4-nitro-1-(p-toluenesulfonyl)pyrazole 13 with cyclohexadiene 2 did not afford the expected cycloadduct but instead gave 1-cyclohexen-2-ylpyrazole 16. This process occurred by hydrolysis of the 1-(p-toluenesulfonyl) group, protonation of the diene and nucleophilic addition of the pyrazolate…

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Hetero Diels-Alder Methodology in Organic Synthesis

Author: Boger, Dale L. & Weinreb, Steven M. Description: Organic Chemistry: A Series of Monographs, Volume 47: Hetero Diels-Alder Methodology in Organic Synthesis focuses on the use of hetero Diels-Alder reactions as pivotal steps in natural product total syntheses. The publication first offers information on N-sulfinyl compounds and sulfur diimides and imino dienophiles. Discussions focus on sulfur dioxide and related compounds, selenium dioxide, sulfur diimide cycloadditions, regiochemical, stereochemical, and mechanistic aspects, iminium salts and neutral imines, oximino compounds, and intramolecular cycloadditions. The text then takes a look at nitroso and…

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Diels-Alder reactions of acyclic a-cyano a,B-alkenones: a new approach to highly substituted cyclohexene system

Author: Amancha, Prashanth K.; Lai, Yi-Chun; Chen, I. Chia; Liu, Hsing-Jang; Zhu, Jia-Liang Description: The Diels-Alder reactions of a variety of acyclic a-cyano a,B-unsaturated ketones have been investigated. With the assistance of boron trichloride, these compounds were found to undergo the cycloaddition readily with dienes to give the corresponding adducts in good to high yields. In addition, some could be further subjected to the reductive alkylation reactions using lithium naphthalenide (LN) and an appropriate alkylating agent, thus allowing for the generation of highly substituted cyclohexenes with the replacement of the…

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The Diels-Alder reaction in total synthesis

Author: Nicolaou, K. C.; Snyder, Scott A.; Montagnon, Tamsyn; Vassilikogiannakis, Georgios Description: The Diels-Alder reaction has both enabled and shaped the art and science of total synthesis over the last few decades to an extent which, arguably, has yet to be eclipsed by any other transformation in the current synthetic repertoire. With myriad applications of this magnificent pericyclic reaction, often as a crucial element in elegant and programmed cascade sequences facilitating complex molecule construction, the Diels-Alder cycloaddition has afforded numerous and unparalleled solutions to a diverse range of synthetic puzzles…

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Mechanochemical Diels-Alder Cycloaddition Reactions for Straightforward Synthesis of endo-Norbornene Derivatives

Author: Zhang, Ze; Peng, Zhi-Wei; Hao, Ming-Feng; Gao, Jian-Gang Description: Under mechanochemical milling conditions, Diels-­Alder cycloaddition of cyclopentadiene with maleic anhydride and maleimide derivatives proceeded very smoothly, affording endo-norbornenes exclusively in quantitative yield. All the transformations were accomplished at room temperature without using any catalyst or organic solvent, thus the workup and purification procedure is very simple. Control experiments on traditional and other tentative conditions were also investigated. Subject headings: Norbornenes; Mechanochemical milling; Solvent-free; Cyclopentadiene; Diels-Alder reaction Publication year: 2010 Journal or book title: Synlett Issue: 19 Pages: 2895-2898 Find…

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A short microwave-assisted synthesis of tetrahydroisoquinolin-pyrrolopyridinones by a triple process: Ugi-3CR–aza Diels-Alder/S-oxidation/Pummerer

Author: Islas-Jacome, Alejandro; Gonzalez-Zamora, Eduardo; Gamez-Montano, Roci­o Description: A series of tetrahydroisoquinolin-pyrrolopyridinones were prepared from an easily accessible aldehyde, a commercially available amine, a readily isolable isonitrile, and maleic anhydride via a triple process: Ugi-3CR-aza Diels-Alder/S-oxidation/Pummerer. The combination of a multicomponent Ugi-type reaction with other post-functionalization processes provides a powerful tool for the preparation of fused polyheterocyclic compounds. Subject headings: Microwave-assisted synthesis; Tetrahydroisoquinolin-pyrrolopyridinones; Ugi-3CR; Aza Diels-Alder cycloaddition; S-oxidation; Pummerer cyclization Publication year: 2011 Journal or book title: Tetrahedron Letters Volume: 52 Issue: 41 Pages: 5245-5248 Find the full text: https://www.sciencedirect.com/science/article/pii/S004040391101272X…

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One-Component Intrinsic Self-Healing Coatings Based on Reversible Crosslinking by Diels-Alder Cycloadditions

Author: Kotteritzsch, Julia; Stumpf, Steffi; Hoeppener, Stephanie; Vitz, Juergen; Hager, Martin D.; Schubert, Ulrich S. Description: Terpolymers containing functional moieties for reversible crosslinking by DA reaction are synthesized for application as self-healing coatings. The polymers are based on a methacrylate backbone containing furan as well as maleimide units in the side chains. No additional crosslinker is required to obtain a self-healing polymeric material. After damage, the material can be heated to a temperature at which the retro-DA reaction takes place. Subsequent cooling to room temperature leads to a healing of…

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Facile synthesis of highly functionalized six-membered heterocycles via PPh3-catalyzed [4+2] annulations of activated terminal alkynes and hetero-dienes: scope, mechanism, and application

Author: Zhang, Qiongmei; Fang, Tong; Tong, Xiaofeng Description: A novel [4+2] annulation between activated terminal alkynes and aza-dienes or oxo-dienes has been developed with the use of triphenylphosphine catalyst (20mol%), which provides a facile method for synthesis of the corresponding highly functionalized dihydropyridines or dihydropyrans in good to excellent yields. The reaction mechanism has also been established, consisting of formal hetero-Diels-Alder reaction catalyzed by PPh3 and [1,3]-proton transfer, which exhibits a large isotopic effect. Subject headings: PPh Catalysis; Hetero-diene; [4+2] Annulations; Heterocycle; H-Transfer; Diels-Alder Publication year: 2010 Journal or book…

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Syntheses of Isomerically Pure Reference Octalins and Hydrindanes

Lee, J.H., Kim, W.H., Danishefsky, S.J. (2009) Tetrahedron Letters, 50(39), 5482-5484 We describe herein the development of efficient and stereoselective synthetic routes to a range of cis- and trans-octalin and hydrindane target compounds. Subject headings: hydrindane; Diels-Alder; cis-octalins; trans-octalins; synthesis Find the full text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2919757/ Find more like this one (cited by): https://scholar.google.com/scholar?cites=15781382976823970932&as_sdt=1000005&sciodt=0,16&hl=en Type: Journal Article Serial number: 349

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