Abstract Reaction of bis (2-chloroethyl) ether (II) with triethyl phosphite afforded diethyl 2- chloroethoxyethylphosphonate (III). This compound reacts with sodium salts of heterocyclic bases to give diethyl esters of N-(2-(2-phosphonylethoxy) ethyl) derivatives of purine and pyrimidine bases IV. Compounds IV on reaction with bromotrimethylsilane and subsequent hydrolysis were converted into N-(2-(phosphonylethoxy) ethyl) derivatives IV.