Pomalidomide-PEG1-azide is a E3 ligase lgand-linker conjugate. Pomalidomide-PEG1-azide incorporates the Pomalidomide based cereblon ligand and a linker. Pomalidomide-PEG1-azide can be used to design a PROTAC BRD4 Degrader-1. Pomalidomide-PEG1-azide is a click chemistry reagent, it contains an Azide group and can undergo copper-catalyzed azide-alkyne cycloaddition reaction (CuAAc) with molecules containing Alkyne groups. It can also undergo strain-promoted alkyne-azide cycloaddition (SPAAC) reactions with molecules containing DBCO or BCN groups.