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Titolo:
Ab initio studies of the radical cation Diels-Alder reaction
Autore:
Haberl, U; Wiest, O; Steckhan, E;
Indirizzi:
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 Univ Bonn, Kekule Inst Organ Chem & Biochem, D-53121 Bonn, Germany Univ Bonn Bonn Germany D-53121 gan Chem & Biochem, D-53121 Bonn, Germany
Titolo Testata:
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
fascicolo: 28, volume: 121, anno: 1999,
pagine: 6730 - 6736
SICI:
0002-7863(19990721)121:28<6730:AISOTR>2.0.ZU;2-K
Fonte:
ISI
Lingua:
ENG
Soggetto:
DENSITY-FUNCTIONAL THEORY; ACCEPTOR-SUBSTITUTED ENAMINES; POTENTIAL-ENERGY SURFACE; CYCLO-ADDITIONS; ELECTRON-TRANSFER; PERICYCLIC-REACTIONS; COPE REARRANGEMENT; SELECTIVITY; DIENES; IONS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Physical, Chemical & Earth Sciences
Citazioni:
68
Recensione:
Indirizzi per estratti:
Indirizzo: Wiest, O Univ Notre Dame, Dept Chem & Biochem, Notre Dame, IN 46556 USA Univ Notre Dame Notre Dame IN USA 46556 Notre Dame, IN 46556 USA
Citazione:
U. Haberl et al., "Ab initio studies of the radical cation Diels-Alder reaction", J AM CHEM S, 121(28), 1999, pp. 6730-6736

Abstract

The radical cation Diels-Alder reaction of the Id-butadiene radical cationwith ethylene, yielding the cyclohexene radical cation, was studied by B3LYP hybrid functional and QCISD(T)//QCISD calculations using the 6-31G* basis set. The intermediates and transition states involved in three different mechanisms, a concerted C-s-symmetric and a stepwise unsymmetric anti [4 + 2] pathway and a stepwise unsymmetric out-gauche pathway leading to vinylcyclobutane, have been considered. The synchronous C-s-symmetric pathway is prevented by a pseudo-Jahn-Teller distortion and is 19 kcal/mol higher in energy than the stepwise pathways. The stepwise anti pathway was found to be the lowest-energy pathway with an activation energy of 0.3 kcal/mol relative to the initially formed ion-molecule complex. The gauche-out pathway, leading to vinylcyclobutane, is 3.5 kcal/mol higher in energy than the anti pathway, leading to cyclohexene. In contrast to earlier calculations by Bauldat the MP2/6-31G*//3-21G level of theory, an ion-molecule complex was found to be part of the reaction pathway and no in-gauche intermediate could belocated. The transition structures and intermediates involved in both stepwise pathways closely resemble the previously described species involved inthe stepwise mechanism of the neutral Diels-Alder reaction.

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Documento generato il 27/11/20 alle ore 13:53:07