Selective syntheses of 6-substituted pyrimidine nucleosides and their interactions with uridine phosphorylase.

Several 6-substituted pyrimidine nucleosides have been prepared by condensation of an N(3)-benzyl or C(4)-methylthio pyrimidine with the appropriately blocked sugar, followed by the use of mild conditions at room temperature for removal of blocking groups. The substrate properties of these nucleosides, which are in the fixed syn conformation, have been examined in the uridine phosphorylase system.