The addition of enynic phosphonates[Formula: see text] to alcohols in the presence of boron trifluoride, leads to γ,δ-ethylenic β-ketophosphonates.[Formula: see text]Yields of 70% have been obtained. Whether Z or E enynic derivates are starting materials the E ketophosphonate is obtained in both cases. The dipole moments of both families of compounds have been measured.