CuX₂-Mediated Halolactonization Reaction of Monoesters of 1,2-Allenyl Phosphonic Acids and Their Suzuki Cross-Coupling Reaction

CuX2-mediated (X = Cl, Br) halolactonization of monoesters of 1,2-allenyl phosphonic acids is presented. The reaction proceeded smoothly under the mild condition for differently substituted allenic substrates giving the 4-halo-2,5-dihydro[1,2]oxaphosphole 2-oxides in good yields. The Suzuki cross-coupling reaction of these bromides and even chlorides with organic boronic acids under the catalysis of PdCl2(Sphos)2 afforded 4-substitueted-2,5-dihydro[1,2]oxaphosphole 2-oxides in moderate to good yields.