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Alder Reaction (alder + reaction)
Selected AbstractsTheoretical Study on Hetero-Diels,Alder Reaction of Butadiene with Benzaldehyde Catalyzed by Chiral InIII ComplexesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 20 2010Xiuli Cao Abstract The mechanism of the hetero-Diels,Alder reaction of butadiene with benzaldehyde catalyzed by chiral N,N, -dioxide/In(OTf)3 complexes was studied theoretically by using density functional theory (DFT) and model system. The computational results indicate that the catalyzed reaction proceeded through a concerted mechanism via a highly zwitterionic transition state. The lowest energy barrier was 11.8 kJ,mol,1, which is 63.0 kJ,mol,1 lower than that of the uncatalyzed reaction. The results indicate that the endo approach is advantageous over the exo approach, because exo transitions states suffer from more steric hindrance than the endo transitions states as a result of interactions among the substrates, the trifluoromethanesulfonic group and the R4 groups of the ligand. The (S) configuration was observed predominantly over the (R) form, because there is no distinguishable repulsion between butadiene and the exo amino side or the endo amino side of the ligand. Besides, the interactions between the terminal hydrogen atoms of butadiene and the oxygen atoms of the trifluoromethanesulfonic group make the structure more stable. Thus, the experimental results were explained well by calculation of the chiral N,N, -dioxide/In(OTf)3 complex catalyzed hetero-Diels,Alder reaction at the molecular level. [source] Lewis Acid Activated Aza-Diels,Alder Reaction of N -(3-Pyridyl)aldimines: An Experimental and Computational StudyEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 11 2010Francisco Palacios Abstract A combined theoretical and experimental study of a Povarov-type cycloaddition reaction suggests an asynchronous concerted process that is favored by double Lewis acid activation with BF3·Et2O; endo selectivity was observed in the reactions between N -(3-pyridyl)aldimines and styrene, cyclopentadiene, or indene, and substituted tetrahydro-1,5-naphthyridine derivatives were obtained in a regio- and stereoselective fashion. [source] Alternative Mechanistic Paths in the Hetero-Diels,Alder Reaction of ,-Oxothiones: A Theoretical StudyEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 21 2007Laura Legnani Abstract DFT calculations at the B3LYP/6-311+G(d,p) level for the C, H, and O atoms and at the 6-311+G(2df,p) level for the S atom were used to study the hetero-Diels,Alder reactions between several ,-oxothiones and ethylene or methyl vinyl ether (MVE). All the transition states and the intermediates along the reaction pathways, as well as the reaction products, were located. The reactions with ethylene are all concerted though asynchronous whereas in the reactions with MVE the electron-releasing character of the methoxy substituent lowers the energy barriers and enhances the asynchronicity and the charge transfer process to such an extent that the reaction may become unconcerted and exhibit a two-step mechanism with a zwitterionic intermediate derived from nucleophilic attack of electron-rich MVE to the sulfur atom of the strongly electrophilically activated ,-oxothiones. The reactions are also favored by the conjugation of the newly formed C=C bond. Moreover, the geometric features of the diene exert a nonnegligible role, as dienes that are planar or almost planar in their ground state show a lower energy barrier. Thus, both geometric and electronic features of the dienes as well as of the dienophiles play a significant role in the easiness of the reactions and in their mechanism. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Synergistic Effect of Pybox Substituents and Lanthanide Cations in Reversing the Asymmetric Induction in the Catalysed Diels,Alder Reaction between 3-Acryloyl-1,3-oxazolidin-2-one and CyclopentadieneEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 14 2004Giovanni Desimoni Abstract The enantioselectivity in the pybox/lanthanide(III) triflate catalysed Diels,Alder reaction between cyclopentadiene and 3-acryloyl-1,3-oxazolidin-2-one is profoundly influenced by the presence of a phenyl group in the 5,-position of the ligand, since it sometimes amplifies, and sometimes reverses the enantioselectivity induced by the 4,-substituent. The results can be summarised in three points. Of the catalysts derived from (4,R,5,R)-4-Me-5-Ph-pybox (6), the ScIII -based one is both strongly endo -selective and strongly enantioselective. Several catalysts derived from (4,R,5,R)- trans -diphenyl-pybox (9) give up to 50% yields of exo - 4 and, at least with PrIII and LaIII, induce excellent ee values in both endo and exo adducts. The (4,R,5,S)- cis -diphenyl-pybox (8) is a novel and valuable ligand, since opposite enantiomers can be obtained with good selectivity simply by changing the cation from ScIII to LaIII. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Synthesis of Novel Polycyclic Indole-Annulated Thiopyranocoumarin Derivatives via Domino Knoevenagel,Hetero- Diels,Alder Reaction in Aqueous MediaHELVETICA CHIMICA ACTA, Issue 5 2010Firouz, Matloubi Moghaddam Abstract An efficient synthesis of polycyclic indole derivatives is achieved via domino Knoevenagel,hetero- Diels,Alder reaction of O -acrylated salicylaldehyde derivatives with dihydroindole-2-thiones in H2O as solvent. The products are formed in good-to-excellent yields with high regio- and stereoselectivity. [source] Steric and Electronic Effects on an Antibody-Catalyzed Diels,Alder ReactionHELVETICA CHIMICA ACTA, Issue 12 2002Yael Gozin A series of substituted thiophene dioxides was tested as diene substrates for the antibody 1E9, which was elicited with a hexachloronorbornene derivative and normally catalyzes the inverse electron-demand Diels,Alder reaction between 2,3,4,5-tetrachlorothiophene dioxide (TCTD) and N -ethylmaleimide (NEM). Previous structural and computational studies had suggested that the catalytic efficiency of this system derives in part from a very snug fit between the apolar active site and the transition state of this reaction. Nevertheless, replacing all the Cl-atoms in the hapten with Br-atoms leads to no loss in affinity (Kd=0.1,nM), indicating substantial conformational flexibility in the residues that line the binding pocket. Consistent with this observation, the 2,3,4,5-tetrabromothiophene dioxide is a good substrate for the antibody (kcat=1.8,min,1, KNEM=14,,M), despite being considerably larger than TCTD. In contrast, normal electron-demand Diels,Alder reactions between NEM and unsubstituted thiophene dioxide or 2,3,4,5-tetramethylthiophene dioxide, which are much smaller or nearly isosteric with TCTD, respectively, are not detectably accelerated. These results show that the electronic properties of the 1E9 active site are optimized to a remarkable degree for the inverse electron-demand Diels,Alder reaction for which it was designed. Indeed, they appear to play a more important role in catalysis than simple proximity effects. [source] Highly Enantio- and Diastereoselective Inverse Electron Demand Hetero-Diels,Alder Reaction using 2-Alkenoylpyridine N -Oxides as Oxo -HeterodienesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 1-2 2009Santiago Barroso Abstract A general catalytic inverse electron demand hetero-Diels Alder reaction for 2-alkenoylpyridine N -oxides is presented. 2-Alkenoylpyridine N -oxides react very efficiently with alkenes in the presence of bisoxazolidine-copper(II) [BOX-Cu(II)] complexes to give chiral dihydropyrans bearing a pyridine ring at the 6-position with very high yields and excellent diastereo- and enantioselectivity. These heterodienes exhibited higher reactivity and enantioselectivity than the corresponding non-oxidized 2-alkenoylpyridines. [source] Organocatalytic Asymmetric Inverse-Electron-Demand Diels,Alder Reaction of Electron-Deficient Dienes and Crotonaldehyde,ANGEWANDTE CHEMIE, Issue 36 2010Jun-Long Li Entscheidendes Enal: Die ausgezeichnet ,,,-regioselektive Titelreaktion unter Dienamin-Katalyse führte effizient zu hoch diastereo- und enantiomerenangereicherten Cyclohexenderivaten mit unterschiedlichen Substituenten (siehe Schema; EWG=elektronenziehende Gruppe, TMS=Trimethylsilyl). [source] Asymmetric Three-Component Inverse Electron-Demand Aza-Diels,Alder Reaction: Efficient Synthesis of Ring-Fused Tetrahydroquinolines,ANGEWANDTE CHEMIE, Issue 22 2010Mingsheng Xie Drei sind nicht einer zu viel: Die Titelreaktion zwischen Aldehyden, Anilinen und Cyclopentadien liefert in Gegenwart von 0.5,5,Mol-% eines N,N, -Dioxid-Scandium-Komplexes in einem Eintopfprozess in guter Ausbeute und mit ausgezeichneter Diastereo- und Enantioselektivität ringanellierte Tetrahydrochinoline mit drei benachbarten Stereozentren. [source] Recrossing and Dynamic Matching Effects on Selectivity in a Diels,Alder Reaction,ANGEWANDTE CHEMIE, Issue 48 2009Zhihong Wang Dr. Bergauf, bergab: Die Produkte der Hetero-Diels-Alder-Reaktion von Acrolein mit Methylvinylketon gehen aus einem einzigen Übergangszustand hervor (siehe Schema), und Trajektorienstudien sagen die Selektivität präzise voraus. In einer Erweiterung von Carpenters Konzept der dynamischen Zuordnung bestimmt die Bewegungsrichtung beim Durchgang durch den Übergangszustand die Selektivität der Produktbildung. Ausgeprägte Rückkehrtrajektorien führen zu einer verminderten Nebenproduktbildung. [source] Cationic-Oxazaborolidine-Catalyzed Enantioselective Diels,Alder Reaction of ,,,-Unsaturated Acetylenic Ketones,ANGEWANDTE CHEMIE, Issue 43 2009Joshua Ine als gute Dienophile: Das kationische Oxazaborolidin 1 ermöglicht die Diels-Alder-Reaktion zwischen acetylenischen Ketonen und cyclischen wie acyclischen Dienen mit ausgezeichneter Ausbeute und 99,%,ee (siehe Schema; Tf=Trifluormethansulfonyl). Sogar bei Dienophilen ohne dem bei anderen Oxazaborolidinium-vermittelten Reaktionen erforderlichen typischen H-Brücken-Motiv findet man eine ausgeprägte asymmetrische Induktion. [source] ChemInform Abstract: Synthesis of Dihydroindoles and Tetrahydroquinolines by the Intramolecular Diels,Alder Reaction of N-Alkenylated 2-Acylamino-3-furancarbonitriles.CHEMINFORM, Issue 43 2010Hiroshi Maruoka Abstract The procedure for the preparation of the title compounds, e.g. (IV), has the advantage of an easy work-up. [source] ChemInform Abstract: Oxo-Diels,Alder Reaction of Danishefsky,s Diene with Aldehydes, Catalyzed by Chiral Tridentate Chromium(III),Schiff Base Complexes.CHEMINFORM, Issue 42 2010Slawomir Miesowicz Abstract The reaction is highly effective in the presence of CSB. [source] ChemInform Abstract: Synthesis of Novel Polycyclic Indole-Annulated Thiopyranocoumarin Derivatives via Domino Knoevenagel-Hetero-Diels,Alder Reaction in Aqueous Media.CHEMINFORM, Issue 40 2010Firouz Matloubi Moghaddam Abstract A highly stereoselective method for the synthesis of novel heteropolycyclic compounds by a domino Knoevenagel,hetero-Diels,Alder reaction is presented which can be performed in water. [source] ChemInform Abstract: Stereoselective Construction of Halogenated Quaternary Stereogenic Centers via Catalytic Asymmetric Diels,Alder Reaction.CHEMINFORM, Issue 35 2010Kazutaka Shibatomi No abstract is available for this article. [source] ChemInform Abstract: Organocatalytic Asymmetric Diels,Alder Reaction of Furan under High Pressure.CHEMINFORM, Issue 34 2010Akiko Mimoto Abstract The combined use of high pressure and organocatalysis promotes the title reaction. [source] ChemInform Abstract: endo-Selective Diels,Alder Reaction of Methacrylonitrile: Application to the Synthesis of Georgywood.CHEMINFORM, Issue 12 2010Andras Borosy Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Natural Transhinone-Like Heterocyclic-Fused ortho-Quinones from Regioselective Diels,Alder Reaction: Synthesis and Cytotoxicity Evaluation.CHEMINFORM, Issue 1 2010Yu-Dong Shen Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Synthesis of 3-Amino-8-azachromans and 3-Amino-7-azabenzofurans via Inverse Electron Demand Diels,Alder Reaction.CHEMINFORM, Issue 48 2009Eduard Badarau Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Catalytic Enantioselective Construction of All-Carbon Quaternary Stereocenters by an Organocatalytic Diels,Alder Reaction of ,-Substituted ,,,-Unsaturated Aldehydes.CHEMINFORM, Issue 35 2009Taichi Kano Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: A New Approach to Di- and Tetrasubstituted 2,3-Dihydropyridin-4(1H)-ones Through Aza-Diels,Alder Reaction Promoted by Silicon Tetrachloride.CHEMINFORM, Issue 27 2009Antonio Massa Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: A Diversity-Oriented Approach to Diphenylalkanes by Strategic Utilization of [2 + 2 + 2] Cyclotrimerization, Cross-Enyne Metathesis and Diels,Alder Reaction.CHEMINFORM, Issue 23 2009Sambasivarao Kotha Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: A Novel Heterotricyclic Assembly Through Intramolecular Imino Diels,Alder Reaction: Synthesis of Pyrrolo[3,4-b]quinolines.CHEMINFORM, Issue 21 2009Mathesan Jayagobi Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Stereoselective Hetero-Diels,Alder Reaction of 3-(Polyfluoroacyl)chromones with Enol Ethers.CHEMINFORM, Issue 11 2009Novel Synthesis of 2-RF -Containing Nicotinic Acid Derivatives. Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Highly Stereoselective Intramolecular Diels,Alder Reaction of Decatrienoates Activated by t-Butoxycarbonyl, Chloro, and Sulfonyl Groups at the Terminal Position.CHEMINFORM, Issue 7 2009Seiichi Inoue Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: An Unexpected Rearrangement of the ,-Phenyl Pyrane Derivatives Prepared via Hetero-Diels,Alder Reaction of Acyclic Vinyl Allenes and Aldehydes.CHEMINFORM, Issue 5 2009Juan M. Ruiz Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Synthesis of Novel Heterocyclic Calixarenes via the Diels,Alder Reaction of Calix[4]bis(spirodienones).CHEMINFORM, Issue 46 2008V. B. Ganga Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Hetero-Diels,Alder Reaction of Propenenitriles with Enol Ethers: A Convenient Approach to Functionalized 3,4-Dihydro-2H-pyrans.CHEMINFORM, Issue 37 2008Aleksandra Palasz Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Efficient Enantioselective Hetero-Diels,Alder Reaction of Brassard,s Diene with Aliphatic Aldehydes: A One-Step Synthesis of (R)-(+)-Kavain and (S)-(+)-Dihydrokavain.CHEMINFORM, Issue 36 2008Lili Lin Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Organocatalyzed Asymmetric Inverse-Electron-Demand Hetero-Diels,Alder Reaction of ,,,-Unsaturated Trifluoromethyl Ketones and Aldehydes.CHEMINFORM, Issue 36 2008Yan Zhao Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] | |||||||||||||||||||||||||