Click chemistry is a term coined by Barry Sharpless to describe chemical reactions that are modular, efficient, broadly applicable, high yield, and free of harmful by-products. The best-known example of a "click" reaction is the copper(I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition (CuAAC), which leads to 1,4-disubstituted penta-membered 1,2, 3-triazole ring.