The discovery of biomimetic rearrangementsl -3 of 1,2-dehydroaspidospermidine (1) and vincadifformine (II) opened new possibilities in the syntheses of bases of the vallesamidine (III, IV) and the eburnane type (for example V). However, till recently the compounds of the group I and II were difficult to obtain, because their precur- sors4 , bases of the vincadifformine type, were demanding in their preparationS -7. Their preparation by dehydrogenationS of saturated compounds of type ...