3-(Diethylphosphono) substituted 1, 5-hexadienes are prepared by the α-regioselective allylation of allylic phosphonates. The products can be converted into vinylic phosphonates via two types of reactions. The first involves Cope rearrangement yielding the terminal vinylphosphonates of the 1, 5-hexadiene system. The second involves γ-silanylation leading to the formation of the 1-silanyl-3-phosphono derivatives of the 2, 5-hexadiene skeleton. ...