8–14 by a retro-Diels-Alder reaction under flash thermolytic conditions. The primaryenamines 1–4 have been identified (IR, 1H and 13C NMR) in a pure state at −80°; at the same temperature, the enamines 5–7, less stable, are already accompanied by their tautomericimines 33 or 34. When warmed up to room temperature, the enamines 1–7 lead, following to their substitution, either to nitrogen heterocycles