Base-Free Direct Synthesis of Alkynylphosphonates from Alkynes and H‑Phosphonates Catalyzed by Cu₂O

A simple and mild methodology for the direct synthesis of alkynylphosphonates is presented. The reaction of a variety of terminal alkynes with dialkyl phosphites in the presence Cu₂O (14 mol %) led to the formation of the corresponding alkynylphosphonates in good to excellent yields. Reactions are performed under air, in acetonitrile as solvent, and in the absence of base or ligand additives. This new methodology is compatible with the presence of a wide variety of functional groups on the starting alkynes and can be scaled up to a gram scale.