Synthesis of some modified guanosine derivatives

Synthesis of some modified guanosine derivatives having substitution at 8-p osition by some amino compounds such as diphenylamine, ethyl hydrazinoforma te, serine, proline and glycine have been described. Furthermore, 2',3'-O-i sopopylidene-8-bromoguanosine reacts with dimethylamine to give 2',3'-O-iso popylidene-8-(N,N-dimethyl)aminoguanosine. The later compound is used for t he 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 has also been measured.