Unprecedented Insertion of Alkynes into a Palladium−Phosphine Bond. A Facile Route to Palladium-Bound Alkenyl Phosphorus Ylides

Refluxing a mixture of (dppm)palladium(II) dichloride (where dppm is bis(diphenylphosphino)methane) and various alkynes in the 1,2-dichloroethane/1,4-dioxane mixed solvents affords a variety of Pd-bound alkenyl phosphorus ylides in modest to good yields. Detailed spectroscopic data for these Pd-bound alkenyl phosphorus ylides along with the X-ray single-crystal structure of 1c are reported. The mechanism and implications for such an unprecedented apparent insertion of alkynes into the Pd−phosphine bond are also discussed.