Thalidomide-O-amido-CH2-PEG3-CH2-NH-Boc is a synthesized E3 ligase ligand-linker conjugate. Thalidomide-O-amido-CH2-PEG3-CH2-NH-Boc incorporates the Thalidomide based cereblon ligand and a linker. Thalidomide-O-amido-CH2-PEG3-CH2-NH-Boc can be used for the synthesis of PROTAC BET degrader[1]. (From patent WO2017180417A1 compound s7).