Abstract Diethyl 2-hydroxyethoxymethanephosphonate (VIII) was converted into diethyl 2- halogenoethoxymethanephosphonates IXa and IXb by reaction with triphenylphosphine and tetrachloromethane or tetrabromomethane; analogous reaction of VIII with p-toluenesulfonyl chloride afforded diethyl 2-(p-toluenesulfonyloxy) ethoxymethanephosphonate (IXc). Reaction of sodium salt of adenine with compounds IX led to 9-(2- ...