Regio- and Stereoselective Hydrophosphorylation of Ynamides for the Synthesis of β‑Aminovinylphosphine Oxides

A metal-free hydrophosphorylation of ynamides with diaryl phosphine oxides has been developed. A highly <i>E</i>-selective and β-regioselective hydrophosphorylation protocol has been established as a general method for the synthesis of diversely hydrophosphinylated products employing an in situ generated electrophilic phosphorus species. Deuterium incorporation experiments suggest that the amino phosphirenium intermediate undergoes a concerted ring-opening hydrolysis upon treatment with H₂O to exclusively furnish β-aminovinylphosphine oxides