Preparation of vinylphosphines by means of free radical addition of diphenylphosphine to alkynes and allenes

Diphenylphosphine adds readily to alkynes and allenes under free radical conditions. Alkynes normally give E-vinylphosphines as the primary (kinetic) product, but Z-vinylphosphines are the main products isolated. Allenes generally give complex product mixtures in which the predominant components are vinyl phosphines formed via addition of the Ph2P. radical to the central carbon atom of the allene fragment.