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Titolo:
Electron-transfer-induced Diels-Alder reactions of indole and exocyclic dienes: Synthesis and quantum-chemical studies
Autore:
Haberl, U; Steckhan, E; Blechert, S; Wiest, O;
Indirizzi:
Univ Bonn, Kekule Inst Organ Chem & Biochem, D-53121 Bonn, Germany Univ Bonn Bonn Germany D-53121 gan Chem & Biochem, D-53121 Bonn, Germany Tech Univ Berlin, Inst Organ Chem, D-10623 Berlin, Germany Tech Univ Berlin Berlin Germany D-10623 an Chem, D-10623 Berlin, Germany Univ Notre Dame, Dept Chem & Biochem, Notre Dame, IN 46556 USA Univ Notre Dame Notre Dame IN USA 46556 Biochem, Notre Dame, IN 46556 USA
Titolo Testata:
CHEMISTRY-A EUROPEAN JOURNAL
fascicolo: 10, volume: 5, anno: 1999,
pagine: 2859 - 2865
SICI:
0947-6539(199910)5:10<2859:EDROIA>2.0.ZU;2-O
Fonte:
ISI
Lingua:
ENG
Soggetto:
ACCEPTOR-SUBSTITUTED ENAMINES; RADICAL PERICYCLIC-REACTIONS; CYCLO-ADDITIONS; CYCLOADDITION REACTIONS; STEPWISE MECHANISM; AMINIUM SALT; RICH ALLENES; AB-INITIO; CATION; 2-VINYLINDOLES;
Keywords:
ab initio calculations; cycloadditions; density functional theory; electron transfer; radical ions;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
47
Recensione:
Indirizzi per estratti:
Indirizzo: Steckhan, E Univ Bonn, Kekule Inst Organ Chem & Biochem, Gerhard Domagk Str 1, D-53121Bonn, Germany Univ Bonn Gerhard Domagk Str 1 Bonn Germany D-53121 , Germany
Citazione:
U. Haberl et al., "Electron-transfer-induced Diels-Alder reactions of indole and exocyclic dienes: Synthesis and quantum-chemical studies", CHEM-EUR J, 5(10), 1999, pp. 2859-2865

Abstract

Photoinduced electron transfer (PET) initiates radical-cation Diels-Alder reactions between indole and exocyclic dienes. As catalysts, triaryl-pyrylium tetrafluoroborates are used. The products are [b]-anellated tetrahydrocarbazoles, which are not accessible through neutral cycloadditions. The resulting structures are of interest because of their DNA intercalating properties. their antitumor activity, and their importance as building blocks of numerous indole alkaloids. When the exocyclic dienes are substituted with anaromatic or heteroaromatic ring, the reaction proceeds with complete regioselectivity. The mechanism is discussed in detail and the potential-energy hypersurface of the radical-cation Diels-Alder reaction is investigated with quantum-chemical methods by variation of the distances of the two newly formed bonds. The potential surface demonstrates the nonsynchronous and nonconcerted reaction pathway. The energies of the different long-bond intermediates, which are local minima on the energy surface, have been calculated with semiempirical, molecular orbital, and density functional methods. Regio- and diastereoselectivities can be explained and predicted by comparing these energies. Quantum-chemical calculations lead to a reaction model that is consistent with the observed products.

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Documento generato il 27/11/20 alle ore 13:25:13