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Updated: Feb 10, 2026

The Preparation and Properties of Thermo-reversibly Cross-linked Rubber Via Diels-Alder Chemistry
Published on: August 25, 2016
Dynamic Intermediates in the Radical Cation Diels-Alder Cycloaddition: Lifetime and Suprafacial Stereoselectivity
Jacqueline S J Tan1, Viivi Hirvonen1, Robert S Paton1,2
1Physical and Theoretical Chemistry Laboratory , University of Oxford , South Parks Road , Oxford OX1 3QZ , U.K.
Abstract:
Cation radical Diels-Alder cycloadditions proceed via an acyclic intermediate that exists on a flat region of the potential energy surface. Competition between cyclization and C-C bond rotation results in varying levels of suprafacial stereoselectivity. Quasi-classical trajectories were used to explore reaction dynamics on this surface. Even though there is no discernible energy barrier toward cyclization, a dynamically stepwise process is found, for which the acyclic intermediate is found to reside for several hundreds of femtoseconds. In a small number of cases, exceptionally long lifetimes (>1000 fs) are found, leading to a loss of alkene stereochemistry.
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