Stercospecific tosylate (− OTs) or azide (N3−) substitution at the C-4 stereocenter of a monosubstituted 1, 3, 2λ5-dioxaphospholane (the equivalent of the C-2 stereocenter in an unsymmetrical 1, 2-diol) is readily achieved by treatment with either p-toluenesulfonic acid (p-TsOH) in tetrahydrofuran solvent or p-TsOH/sodium azide in acetonitrile solvent, respectively.