ANTIVIRAL ACTIVITY OF C-ALKYLATED PURINE NUCLEOSIDES OBTAINED BY CROSS-COUPLING WITH TETRAALKYLTIN REAGENTS

2-, 6-, And 8-alkylated (methyl, ethyl, and vinyl) adenosine analogues were synthesized by a palladium-catalyzed cross-coupling of a tetraal kyltin with the halogenated purine nucleosides. The synthesis of the 8 -substituted analogues was accomplished using a transient protection p rocedure. The 6-alkylated-9-beta-D-ribofuranosylpurines as well as 2-e thyladenosine were cytotoxic at relatively low concentrations (0.8-10 mug/mL). 8-Methyladenosine was a potent and selective inhibitor of vac cinia virus, whereas 8-ethyl- and 8-vinyladenosine were specifically i nhibitory to respiratory syncytial virus. 8-Vinyladenosine displayed p articular activity against herpes simplex virus (type 1).