Lenalidomide 4′-PEG1-azide (Compound 4g) is a lenalidomide-derived azide. Lenalidomide 4′-PEG1-azide incorporates the Lenalidomide based cereblon ligand and a linker. Lenalidomide 4′-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. Strain-promoted alkyne-azide cycloaddition (SPAAC) can also occur with molecules containing DBCO or BCN groups.^[1].