Chalcones and Chromones in Copper-catalyzed Azide–Alkyne Cycloadditions (CuAAC)

Click chemistry has emerged as a valuable synthetic tool for the assembly of diverse molecular units. In particular, the copper-catalyzed azide–alkyne cycloadditions (CuAAC) revealed to be extremely versatile and are currently used for the synthesis of molecules with a wide range of applications. Accordingly, CuAAC reactions have been extensively used for the functionalization of phenolic compounds, many of them with well-known biological properties. Herein, an overview of the most important advances in the application of CuAAC reactions to chalcones and chromones, including flavones, since 2002 is presented. In particular, this review discusses the use of azidochalcones, azidochromones, alkynylchalcones and alkynylchromones in 1,3-dipolar cycloadditions. The biological properties of some of the resulting conjugates, where the two units are linked by a 1,2,3-triazole bridge, are also presented. In some reported examples, the new conjugates revealed additive activities which represent a promising step forward in medicinal chemistry.