Abstract 1-[(S)-3-Hydroxy-2-(phosphonomethoxy) propyl] cytosine (HPMPC, cidofovir) was modified by substitution on the base moiety in positions C-5 and N 4. Key intermediates of these syntheses, diisopropyl esters of (S)-1-[2-(phosphonomethoxy)-3-(triphenylmethoxy) propyl]-5-alkylcytosines (6 and 7) prepared from 5-alkyl-4-methoxypyrimidin-2 (1H)-ones were transformed to the corresponding 5-substituted cytosine or N 4-alkylcytosine ...
