2'-O-Benzyl-4-methylthiouridine (III) and 2'-O-benzylcytidine (VI) were obtained by respective treatment of 4-methylthiouridine (II) and cytidine (V) with benzyl bromide in the presence of sodium hydride. By this reaction, highly specific benzylation of 2'-hydroxyl group of the ribonucleosides was achieved. The both compounds (III) and (VI) could easily be converted to 2'-O-benzyluridine (IV) which is an important intermediate in the synthesis of oligonucleotide.
