Revisiting the stability of endo/exo Diels-Alder adducts between cyclopentadiene and 1,4-benzoquinone

Autor(es)

Tormena, Claudio F. ^[1] ; Lacerda, Jr., Valdemar ^[2] ; de Oliveira, Kleber T. ^[3]

Afiliação do(s) autor(es)

^[1] Univ Estadual Campinas, Inst Quim, Dept Quim Organ, BR-13083970 Campinas, SP - Brazil

^[2] Univ Fed Espirito Santo, Ctr Ciencias Exatas, Dept Quim, BR-29060900 Vitoria, ES - Brazil

^[3] Univ Fed ABC, Ctr Ciencias Nat & Humanas, BR-09210170 Santo Andre, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Journal of the Brazilian Chemical Society; v. 21, n. 1, p. 112-118, 2010.
• Citações Web of Science: 7

Resumo

In this work it is presented a detailed theoretical analysis of the relative stability of endo/exo Diels-Alder adducts formed by the reaction between cyclopentadiene (1) and 1,4-benzoquinone (2). The intrinsic reaction coordinate (IRC) showed the existence of only one transition state for the reaction studied, for both endo 3 and exo 4 adducts. The energies of both adducts were obtained at high level of theory (CBS-Q) confirming that the endo adduct is more stable than exo, which is in the opposite way to the observed in reactions that usually follow Alder's rule. An electronic structure analysis was performed through NBO methodology, indicating that the attractive delocalization interaction predominates over the steric repulsive interaction in the endo adducts. In summary, for the studied cycloaddition reaction the endo adduct is the thermodynamic and kinetic product, which can be also confirmed by experimental data mentioned in this work. (AU)

• Processo FAPESP: 05/59649-0 - Estudos de estrutura eletrônica e molecular através de métodos espectroscópicos e cálculos teóricos
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