Base-promoted regio- and diastereoselective synthesis of tri- and tetra-substituted homoallenyl phosphine oxides <i>via</i> alkynyl enones

A novel base-promoted method for hydrophosphinylation of alkynyl enones with secondary phosphine oxides has been developed. Using inexpensive and commercially available potassium carbonate, a variety of functionalized tri-substituted allene products were synthesized with exclusive regio- and diastereoselectivity under mild conditions. Furthermore, a one-pot, two-step, three-component tandem hydrophosphinylation/Heck reaction efficiently produced tetra-substituted homoallenyl phosphine oxides in excellent yields, demonstrating a relatively broad substrate scope.