| abstract |
There are disclosed s-triazolo[3,4-i]purine derivatives represented by formula: <CHEM> wherein Y-Z represents <CHEM> where R<4> represents hydrogen, alkyl, substituted or unsubstituted aromatic heterocyclic group or substituted or unsubstituted aryl; and X<2> represents oxygen, sulfur or NH; each of R<1> and R<2> independently represents hydrogen, alkyl, cycloalkyl, aralkyl or substituted or unsubstituted aryl; R<3> represents alkyl, cycloalkyl, aralkyl or substituted or unsubstituted aryl; X<1> represents oxygen or sulfur; and <CHEM> represents a single bond or a double bond or pharmaceutically acceptable salts thereof. |