The primary hydroxyl group of adenosine (I) is chlorinated by means of SOCl2 to afford chloride (II), which is then displaced by methylamine at 55 C in a pressure vessel to furnish amine (III). Subsequent alkylation of (III) with the allyl chloride (IV) in hot DMF provides (V). After esterification of diol (V) with acetic anhydride, the resultant diacetate (VI) is subjected to acid-catalyzed N-Boc group cleavage to furnish the title compound.