Abstract N 4-Substituted derivatives of HPMPC were synthesized in four-step synthesis which included treatment of 4-methoxypyrimidin-2 (1H)-one (1) with (S)-[(trityloxy) methyl] oxirane in DMF. Condensation of intermediary 1-[2-hydroxy-3-(trityloxy) propyl]-4- methoxypyrimidin-2 (1H)-one (2) with (diisopropoxyphosphoryl) methyl tosylate in the presence of sodium hydride resulted in fully protected 4-methoxypyrimidin-2 (1H)-one ...