cis-Vinylphosphonates and 1,3-Butadienylphosphonates by Zirconation of 1-Alkynylphosphonates

Abstract
[structure in text] Addition of "zirconocene" to 1-alkynylphosphonates gives three-membered zirconacylces that can be hydrolyzed to cis-vinylphosphonates or further reacted with alkynes/hydrolysis to give substituted (Z,E)- and (E,E)-1,3-butadienylphosphonates.