A computational study of the thermal cycloreversion of 2,2,6-trimethyl-4H-1,3-dioxin-4-one and a related species: Retro-Diels-Alder reaction or concerted nucleophilic attack?

Shawn W E Eisenberg, Mark J. Kurth, William H. Fink

Research output: Contribution to journalArticle

24 Scopus citations

Abstract

Calculations up to the MP2/6-31G*//HF/3-21G level have been carried out to study the thermal cycloreversion of 2,2,6-trimethyl-4H-1,3-dioxin-4-one (1) and 2,2,4-trimethyl-6H-1,3-oxazin-6-one (3). At this level of calculation, the enthalpy of activation for the thermal cycloreversion of dioxinone 1 was found to be 31.3 kcal/mol with zero-point vibrational energy correction. The experimental value for the reaction in solution is 30.4 kcal/mol. The enthalpy of activation for the as of yet unsynthesized oxazinone 3 was found to be 44.2 kcal/mol with zero-point correction. Contrasting with the standard view that the thermal cycloreversion of dioxinone 1 is a retro-Diels-Alder reaction is the structural information from the HF/3-21G-optimized transition state 5 which shows the plane of the acetone dienophile tilted roughly 90° to the plane of the acylketene diene.

Original languageEnglish (US)
Pages (from-to)3736-3742
Number of pages7
JournalJournal of Organic Chemistry
Volume60
Issue number12
StatePublished - 1995

ASJC Scopus subject areas

  • Organic Chemistry

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