Regioselective synthesis of 9-substituted-8-azaguanines (5-amino-3-substituted-3,6-dihydro-7H-1,2,3-triazolo[4,5-d]pyrimidin-7-one)

By modifying previously described methods for the synthesis of 9-substituted-guanines from imidazoles, we have developed a new procedure for the regioselective synthesis of 9-substituted-8-azaguanines (5-amino-3-substituted-3,6-dihydro-7H-1,2,3-triazolo[4,5-djpyrimidin-7-one) from triazoles in high yields. The method seems suitable for the introduction of a variety of substituents including sugars, carbocyclic, acyclic and carboacyclic chains.