Purine nucleoside modifications by palladium catalyzed methods

A method for the preparation of a purine nucleoside modified at the 2-, 6-, or 8-positions of the purine ring comprising the steps of:

• a) reacting a purine starting material containing a halogen leaving group attached to the 2-, 6-, or 8-positions of said purine starting material with an organotin compound of the formula R.sup.2 SnR.sup.1.sub.3, wherein R.sup.2 displaces the leaving group from the purine starting material, wherein R.sup.1 is a C1 to C15 alkyl, and R.sup.2 is selected from the group consisting of a C1 to C15 alkyl and a substituted or unsubstituted C1 to C15 alkenyl or C6 to C12 aryl, in the presence of a palladium catalyst PdL.sub.3, wherein L is a ligand of palladium, and
• b) isolating and purifying said purine nucleoside.