Abstract 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 Ph 2 P. radical to the central carbon atom of the allene fragment.
