To examine the structural parameters necessary for antiviral efficacy of certain purine nucleosides, several QBD-ribofuranosylpurine-6-carboxamides have been synthesized. Glycosylation of the Me3Si derivative of purine-6-carboxamide with protected ribofuranose in the presence of a Lewis acid gave the blocked nucleoside which on deprotection furnished 9-BD-ribofuranosylpurine-Gcarboxamide (6a). Alternatively, 6a was synthesized ...