Copper-Catalyzed Synthesis of 1,2,3-Triazoles

3-Triazoles are attractive compounds and widely used in materials, drugs, and bioconjugation chemistry [124-136]. 1,2,3-Triazoles could be synthesized by 1,3-dipolar cycloaddition of azides with alkynes under thermal conditions via the activation of C-H bond of alkyne [137-141]. The developments of Click reaction, copper-catalyzed azide-alkyne cycloaddition (CuAAC), provide an efficient pathway for the synthesis of 1,2,3-triazoles [142, 135, 143, 144]. They have been well reviewed and we don t discuss it in detail in this chapter. 

5- Disubstituted tetrazoles are ubiquitous structural units in organic synthesis. The functionalized starting materials are needed for the synthesis of 

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