Pomalidomide 4′-PEG3-azide is a synthesized E3 ligase ligand-linker conjugate that incorporates the Pomalidomide-based cereblon ligand and a linker. Pomalidomide 4′-PEG3-azide can be used for the synthesis of iRucaparib-TP3 (Compound 3). iRucaparib-TP3 is a highly efficient PARP1?degrader based on Rucaparib by using the PROTAC approach.