The reaction mechanism of CuAAC involves the coordination of the [copper(I) catalyst]() to the terminal alkyne to form a copper-acetylide complex. This complex then reacts with the azide to form a five-membered ring intermediate, which subsequently rearranges to form the 1,2,3-triazole product. The high efficiency and specificity of this reaction are attributed to the stability of the copper-acetylide and the intermediate triazole complex.
