Several synthetic methodologies towards differently substituted 1,2,3-triazolylpurine nucleosides have been developed during this thesis. The nucleophilic substitution reactions of 2,6-bis-triazolylpurine, 2,6-diazidopurine and 2,6-dichloropurine nucleosides with different nucleophiles have been studied and the reactivity of these key-intermediates has been compared. It is demonstrated that triazolyl ring at the C(6) position of purine is acting as a good leaving group in nucleophilic heteroaromatic substitution reactions. Substituted monotriazolylproducts possess interesting fluorescent properties. A number of novel triazolyl compounds have promising biological activities: agonist activity of adenosine A3 and purinergic P2Y12 receptors; antiviral activity against yellow fever virus, Chikungunya and enteroviruses. These compounds are also cytotoxic for cancer cell lines HT-1080 and MG-22A.