Quantum Tunneling Instability in Pericyclic Reactions: The Cheletropic, Coarctate, and Ene Cases.

Some retro-pericyclic reactions, as a result of their high exothermicity and short trajectories, are the perfect ground for heavy atom tunneling molecular decompositions, also known as "quantum tunneling instability" (QTI). Considering this effect, in our first installment [Frenklach, A.; Amlani, H.; Kozuch, S. Quantum Tunneling Instability in Pericyclic Reactions. J. Am. Chem. Soc. 2024, 146 (17), 11823-11834, DOI: 10.1021/jacs.4c00608], we computed several retro-Diels-Alder reactions, predicting that many studied reactants cannot be isolated. Herein, we will explore the QTI of retro-cheletropic, coarctate, and ene exemplars, where again we hypothesize the impossibility to detect their reactants.