Green synthesis of α-hydroxy phosphonates containing unsaturated organochalcogenyl moiety

A simple and efficient protocol for the chemoselective synthesis of α-hydroxy phosphonates containing unsaturated alkoxy/phenoxy or organosulfanyl moiety has been developed. This approach was performed by Pudovik reaction from readily available organochalcogenyl enals and dialkyl phosphites in a solvent-free system, using 0.25 equiv. CaO as a catalyst at room temperature, which provided the target phosphonates in high yields.