Rhodium-catalyzed reaction of 1-alkynylphosphines with water yielding (E')-l-alkenylphosphine oxides

Treatment of 1-alkynylphosphines with a rhodium catalyst in l,4-dioxane/H₂0 at reflux provides (E)-1 -alkenyl-phosphine oxides in good yields with perfect stereoselectivity. The reaction proceeds as follows. Oxidative addition of 1 -alkynylphosphine to rhodium followed by hydrolysis yields the corresponding terminal alkyne and diphenylphos-phine oxide. Rhodium-catalyzed hydrophosphinylation of the terminal alkyne then proceeds to afford (E)-1 -alkenylphosphine oxide.