Post-synthetic conversion of 5-pivaloyloxymethyluridine present in a support-bound RNA oligomer into biologically relevant derivatives of 5-methyluridine

A post-synthetic reaction of 5-pivaloyloxymethyluridine (present in a support-bound RNA oligomer) with various nucleophilic reagents furnished efficiently the corresponding products bearing one of the tRNA wobble 5-methyluridines (mnm(5)U, cmnm(5)U, tm(5)U, nm(5)U, inm(5)U or cnm(5)U). The syntheses of oligoribo-nucleotides modified with inm(5)U and cnm(5)U are reported for the first time.