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 C 2 H 5 ONa 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.