Ruthenium-Catalyzed ortho-Alkenylation of Phenylphosphine Oxides through Regio- and Stereoselective Alkyne Insertion into C-H Bonds

Direct ortho-substitution took place efficiently upon treatment of tri-, di-, and monoarylphosphine oxides with internal alkynes in the presence of a ruthenium catalyst to produce (o-alkenylphenyl)phosphine oxides regio- and stereo-selectively. Chemoselective reduction of a product gave the corresponding (o-alkenylphenyl)phosphine, which may be useful as a ligand for transition metals.