Copper-catalyzed reaction of an azide with an alkyne to form a 5-membered heteroatom ring, also known as Cu(I)-Catalyzed Azide-Alkyne Cycloaddition (CuAAC), is a powerful reaction for the synthesis of bioconjugates.

Terminal alkyne and azide groups are almost never encountered in natural molecules, so they must be first introduced into the biomolecules to be linked. Alkyne-containing DNA can be prepared with an alkyne phosphoramidite during standard oligo synthesis. Azide or alkyne groups can be attached to proteins by using bifunctional adapter molecules with an NHS ester moiety.

Aqueous DMSO, DMF, acetonitrile, alcohols, or pure water and buffers can be used for the Click chemistry reaction. The reaction is compatible with a wide range of functional groups.

The following list includes only a few of reagents for Click chemistry. Please check other categories, especially alkynes and azides.