Isotope effects and the distinction between synchronous, asynchronous, and stepwise Diels-Alder reactions

Daniel A. Singleton, Brian E. Schulmeier, Chao Hang, Allen A. Thomas, Shun Wang Leung, Steven R. Merrigan

Research output: Contribution to journalArticle

72 Scopus citations


A variety of symmetrical or nearly symmetrical Diels-Alder reactions are studied by a combination of experimental isotope effects, theoretical calculations, and rate observations. Becke3LYP calculations predicted highly asynchronous transition structures for Diels-Alder reactions of bis(boryl)acetylenes, dialkyl acetylenedicarboxylates, triazolinediones, and dialkyl maleates. Rate observations and kinetic isotope effects are consistent with these predictions, though the experimental support for the calculated structures is notably ambiguous in some cases. A concerted mechanism is supported for the retro-Diels-Alder reaction of norbornene. Overall, Diels-Alder reactions appear to be only very weakly biased toward synchronous transition states.

Original languageEnglish (US)
Pages (from-to)5149-5160
Number of pages12
Issue number24
StatePublished - Jun 11 2001



  • Asynchronous transition state
  • Diels-Alder reaction
  • Isotope effect

ASJC Scopus subject areas

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry

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