Recent Advance in Copper-Free Click Chemistry Using Cyclooctynes, and Applications for Living Systems

Abstract

Cu(I)-catalyzed azide-alkyne cycloaddition, considered as a “click chemistry”, has been used in many fields of chemistry, including chemical biology. But, because of cytotoxicity of Cu(I), applications of this reaction for living systems have been restricted. Cyclooctyne which has high ring strain energy reacts with azide without Cu(I) catalyst. This reaction is often called “copper-free click chemistry (CFCC)”. This short review summarizes the recent advance in CFCC using cyclooctynes.