Synthesis of some modified guanosine derivatives

Synthesis of some modified guanosine derivatives having substitution at 8-position by some amino compounds such as diphenylamine, ethylhydrazinoformate, serine, proline and glycine have been described. Furthermore, 2,3-O-isopropylidene-8-bromoguanosine reacts with dimethylamine to give 2,3-O-isopropylidene-8-(N, N-dimethyl)aminoguanosine. The later compound is used for the synthesis of 2,5-anhydronucleoside. The cyclonucleoside is treated with H2S in dry pyridine to give 5-thioguanosine derivative 11. The biological activity of the synthesized compounds have also been measured.