“…11 The synthesis of the above-mentioned mixed diesters can be accomplished by the condensation of an N-protected phosphonate monoester with the hydroxyl moiety of a derivative of a glycolic, lactic or mandelic acid using coupling agents such as DIAD/PPh 3 , 31-34 BOP or PyBOP. 35,36 The same products have also been prepared from phosphonochloridates by treatment of monoesters with thionyl chloride [10][11][12]14,23,24 or by oxidative chlorination with carbon tetrachloride. 11,18 Next, the demethylation of unsymmetrical diesters using TMSBr, 12,20,22,31,32,34,35 LiSPr, 10,23,24 LiOH 14,19 or by hydrogenolysis of the protecting benzyl group 6,29 led to the desired phosphonic acid monoesters.…”