Abstract As part of the valence tautomeric system cyclooctatetraene (2) bicyclo [4.2. 0] octa- 2, 4, 7-triene (3), the monocyclic polyene (2) reacts as a dienophile with the diazadiene 3, 6- bis (trifluoromethyl)-1, 2, 4, 5-tetrazine (1) to form after N 2-elimination two products: The 1: 1- adduct 6, a cycloocta [d] pyridazine, and the tetracyclic bis-Diels-Alder cycloadduct 9. Depending on solvent polarity and temperature, compound 6 displays interesting novel ...
