Synthesis of 2′,5′-Dideoxyuridine-5′-phosphonates

Methyl 2,5‐dideoxy‐5‐iodo‐3‐O‐pivaloyl‐D‐erythro‐pentofur‐anoside (5) was synthesized from 2‐deoxy‐D‐ribose and treated with triethyl phosphite to give the phosphonate 6. Reaction of 6 with silylated 2,4‐dihydroxypyrimidine 7 in the presence of trimethylsilyl trifluoromethanesulfonate as catalyst afforded nucleoside phosphonates 8 and 9 which were deprotected with C2H5ONa in ethanol to give the diethyl 2′,5′‐dideoxyuridine‐5′‐phosphonate 10 and its α‐anomer 11. No activity was found for the nucleosides 8–11 against HIV or HSV‐1.