Abstract Reaction of a trialkyl phosphite (VI) or sodium salt of dialkyl phosphite (V) with bromomethyl acetate afforded dialkyl acetoxymethanephosphonates VII which were alcoholyzed to dialkyl hydroxymethanephosphonates VIII. Tosylation of the compounds VIII gave dialkyl p-toluenesulfonyloxymethanephosphonates IX which on reaction with 2', 3'-O- isopropylideneribonucleosides (I), 2', 3'-O-ethoxymethyleneribonucleosides (XI) or 3'-O- ...
