of a functionalized isopreneunit on the E or Z terminal methyl of terpenoids was achieved by N-ylide rearrangement of the common ammonium salts under selected reaction conditions. A 1,5-diene or conjugated triene skeleton can be furnished by reductive or oxidative removal of the amino group of the rearrangement product, respectively. As an application to natural-product synthesis, all-(E)-terpenoid