Synthesis of 3′‐azido‐2′,3′‐dideoxy‐β‐ D ‐ arabino ‐hexopyranosyl nucleosides

The α,β‐unsaturated D ‐sugar aldehyde 2 , prepared from tri‐ O ‐acetyl‐ D ‐glucal, was converted into 1‐ O ‐acetyl‐3‐azido‐2,3‐dideoxy‐α‐ D ‐ arabino ‐pyranose ( 3 ) by reaction with sodium azide in a mixture of acetic acid and water followed by acetylation. Reaction of 3 with silylated pyrimidines using TMS triflate as catalyst followed by deprotection with saturated ammonia in methanol afforded 3′‐azido‐2′,3′‐dideoxy‐β‐ D ‐ arabino ‐hexopyranosyl nucleosides 4 .