CG-PEG5-azido is a PROTAC linker classified under the PEG category, instrumental in synthesizing PROTAC molecules. This compound acts as a click chemistry reagent, incorporating an Azide group that facilitates copper-catalyzed azide-alkyne cycloaddition (CuAAc) with Alkyne-containing molecules. Additionally, it can undergo strain-promoted azide-alkyne cycloaddition (SPAAC) with molecules bearing DBCO or BCN groups.