Alkenylzirconocene-Mediated Preparation of Alkenylphosphines

Alkenylphosphines with various substituents were prepared by the reaction of an alkenylzirconocene with a chlorophosphine. Reactions of (alpha-unsubstituted alkenyl)zirconocenes with Ph2PCl or PhPCl2 gave the corresponding alkenylphosphines in good yields. On the other hand, direct reactions of (alpha-unsubstituted alkenyl)zirconocenes with iPr2PCl did not proceed. Analogously, (alpha-substituted alkenyl)zirconocenes did not react with chlorophosphines directly. However, these reactions proceeded in the presence of CuCl affording the corresponding alkenylphosphines as CuCl complexes. Treatment of the copper complexes with Na2(dtc) (dtc = N,N-diethyldithiocarbamate) or Na4(edta) liberated free alkenylphosphines from the copper centers. The overall protocol could be applicable to preparation of a variety of alkenylphosphines from alkynes via alkenylzirconocene species.