Synthesis of various 5‐substituted 2′‐deoxy‐3′‐5′‐di‐O‐acetyluridines

The Pd(0)‐catalyzed coupling reaction of β‐5‐iodo‐2′‐deoxy‐3′,5′‐di‐ O ‐acetyluridine with various heteroaryltrimethylstannyl compounds gave the corresponding β‐5‐heteroaryl‐2′‐deoxy‐3′,5′‐di‐ O ‐acetyluridines in moderate yields. This direct coupling approach for nucleosides represented an interesting alternative to the 5‐heteroaryl functionalization of pyrimidines followed by the Hilbert‐Johnson glycosylation reaction which often yields mixtures of the α and β anomers.