Synthesis of Purine-based Triazoles by Copper (I)-catalyzed Huisgen Azide-Alkyne Cycloaddition Reaction

An efficient protocol for the synthesis of substituted 1,2,3-triazol-9H-purines via copper (I)-catalyzed click chemistry of 2,6-dichloropurine with aromatic azide has been reported. A wide range of 1,4-disubstituted triazoles (N-9 substituted purines) was accessible in good-to-excellent yields with remarkable functional group tolerance. The base-catalyst ratio was tuned to achieve optimum reaction condition (>95% conversion and purity in most cases). Furthermore, the structure of 4i has been unambiguously assigned by X-ray crystallographic study to yield structural information on the 1,3-dipoles entering the reaction.