Functional group tolerance in the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction was evaluated using a functional group evaluation (FGE) kit. The results revealed that selecting an appropriate ligand is important for promoting the CuAAC reaction in the presence of nitrogen-containing functional groups and that the significant reduction in reactivity caused by a thiol additive can be circumvented by switching to strain-promoted azide-alkyne cycloaddition (SPAAC).
Manabe et al. (Wed,) studied this question.