“Umpulong” of reactivity at the C-6 position of uridine: a simple and general method for 6-substituted uridines

Lithiated 2′,3′-O-isopropylidine-5′-$\text{O}$-methoxymethyl-uridine was found to react with a variety of electrophilic reagents regiospecifically at the C-6 position. The protecting groups of the ribose moiety in the 6-functionalized products were concurrently removed under mild conditions with aqueous trifluoroacetic acid. Consequently, the present method permits simple and general syntheses of 6-substituted uridines.