Synthesis and Biological Activity of 6-Substituted-2-Oxo-Purine Nucleosides

We have synthesized various 6-substituted 2-oxo-purine nucleosides from key intemediate, 6-[(4-methylphenylthio)-2-oxo-9(2, 3, 5tri-o-acetyl-$\beta$-D-ribofuanoslyl)]-2, 3- dihydropurine in relatively high yields by one step nucleophilic substitution. Various isoguanosine, xanthosine analogs and other 2-oxo-purine nucleosides containing nitrogen, sulfur and oxygen at C-6 of purine base were easily obtained by this method. The structures of the products were established on the basis of their spectral data studies. And cytotoxicity of resulting synthetic 6-substituted-2-oxo-purine nucleosides against some tumor cell-lines was examined. $Ed_{50}$ values of these synthetic compounds were above $100\;{\mu}g/ml$ except isoguanosine, $N^6$-methyl isoguanosine and thioxanthosine analogs.