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Titolo:
Ab initio studies of [1,5]-H shifts: Pentadiene and beyond
Autore:
Saettel, NJ; Wiest, O;
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
Titolo Testata:
JOURNAL OF ORGANIC CHEMISTRY
fascicolo: 8, volume: 65, anno: 2000,
pagine: 2331 - 2336
SICI:
0022-3263(20000421)65:8<2331:AISO[S>2.0.ZU;2-Z
Fonte:
ISI
Lingua:
ENG
Soggetto:
1,5-SIGMATROPIC HYDROGEN SHIFTS; TRANSITION STRUCTURES; PHENYL ACETATE; GAS-PHASE; REARRANGEMENTS; DNA; CYCLOPENTADIENE; 1,3-PENTADIENE; BIOSYNTHESIS; VITAMIN-B12;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Physical, Chemical & Earth Sciences
Citazioni:
52
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:
N.J. Saettel e O. Wiest, "Ab initio studies of [1,5]-H shifts: Pentadiene and beyond", J ORG CHEM, 65(8), 2000, pp. 2331-2336

Abstract

Ab initio calculations of the [1,5]-H shift, in (3Z)-penta-1,3-diene and other substituted pentadienes and heteroanalogues using the hybrid density functional Becke3LYP with the 6-31G* basis set are presented. Electron-donating substituents, such as methoxy in (3Z)-3-methoxypenta-1,3-diene 1, or heteroatoms such as a nitrogen atom in (Z)-ethylidenevinylamine 2, (1Z)-buta-1,3-dienylamine 3, (2Z)-but-2-enylideneamine 4, (Z)-allylidenemethylamine 5, and methylene-(Z)-propenylamine 6 are introduced. The electron-withdrawing fluoride is substituted for the hydrogen atoms in (3Z)-3-fluoropenta-1,3-diene 7, (3Z)-2,4-difluoropenta-1,3-diene 8, (3Z)-1, 1',2,3,4,5,5'-heptafluoropenta-1,3-diene 10, (1E,3E)-1,3,5-trifluoropenta-1,3-diene II, and (1Z,3E)-1,3,5-trifluaropenta-1,3-diene 13. A detailed analysis of the geometries, energies, and electronic characteristics of the sigmatropic transpositioncompared to those of the unsubstituted case provides insights into substituent effects of this prototype of pericyclic reaction. The inductive and mesomeric effects of heteroatoms or heterosubstituents are of a great importance and in a continuous balance in the energetics of the transformation. Sterics can also play an important role due to the geometrical constraints ofthe reaction. As a general trend, decreasing the electron density of the pi system destabilizes the aromatic transition structure and increases the activation energy, and vice versa.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 04/12/20 alle ore 16:43:09