Diels-Alder-Reaktionen. VII. Über die Isomerisierung von 2-Vinylbicyclo[2,2,1]hepten-(5)

Diels-Alder Reactions. VII. The Isomerization of 2-Vinylbicyclo2,2,1]hept-5-ene The isomerization of exo/endo-2-vinylbicyclo2,2,1]-hept-5-ene in the presence of Na/Al₂O₃ rapidly gives the thermodynamic equilibrium between exo- and endo-2-vinylbicyclo-2,2,1]hept-5-ene and cis- and trans-2-ethylidenbicyclo2,2,1]-hept-5-ene. Far more slowly vinylnortricyclene is formed, which enriches to an equilibrium concentration of about 75% at 60°C. The dependence of equilibrium constants of isomerization on temperature allows the calculation of enthalpies and entropies of isomerization.