LAUSR

Herein reported is a photoinduced hydrophosphination reaction of terminal alkynes with tri(o-tolyl)phosphine to form alkenylphosphonium salts. The reaction is more sustainable than conventional methods since it dispenses with the need for elaborated starting materials and precious transition metals. The o-methyl groups of tri(o-tolyl)phosphine play two important roles: (1) to guide the phosphorus radical to add onto the terminal sp carbon and (2) to donate a hydrogen atom onto the developing sp2 carbon radical intramolecularly.