Experiment Meets Theory: Cope Rearrangements and Thermal E/Z Isomerisations of Terpenoid Hydrocarbons

Abstract Several terpenes are known that can undergo a Cope rearrangement. Prominent examples include germacrene A and hedycaryol that show a Cope rearrangement already slightly above room temperature. In the present study the Cope rearrangements of several terpenes and eventually co‐occurring thermal E / Z isomerisations were investigated experimentally for their minimum required temperatures and for their states of equilibrium. The experimental findings were supported by computational assessments of free activation energies (ΔG ≠ ) as well as relative Gibbs free energies of the reactants (ΔG).