Calculated transition states for the cycloaddition and retrocycloaddition, as well as the structures of the intermediate cycloadducts. The numbers in brackets represent the free energies G s (353 K), including solvation (PW6B95-D3//TPSS-D3+COSMO-RS/1,4-dioxane), in kilocalories per mole. The calculation is in agreement with the experimental results, which indicates the origin of the regioselectivity and the thermaldynamically favoured rearomatization process.
