Direct Approach to α-Hydroxyphosphonic and α,ω-Dihydroxyalkane-α,ω-bisphosphonic Acids by the Reduction of (Bis)acylphosphonic Acids

Acylphosphonic and bisacylphosphonic acid sodium salts were directly reduced by sodium borohydride to the corresponding hydroxyphosphonates and dihydroxyalkanebisphosphonates. The solution conformation of the (bis)hydroxyphosphonic acid sodium salts, elucidated from the homonuclear and heteronuclear coupling constants of the proton adjacent to the hydroxy and the phosphonic groups, was identical with the solid-state conformation as determined for 1-hydroxy-2-phenylethylphosphonic acid, a representative compound, by X-ray crystallography.