Thalidomide -NH-PEG3-NH-Boc is an E3 Ligase Ligand-Linker Conjugate consisting of Thalidomide and NH-PEG3-NH-Boc. Thalidomide -NH-PEG3-NH-Boc acts as a ligand for Cereblon to recruit CRBN protein. The Boc protecting group at the end of Thalidomide -NH-PEG3-NH-Boc can be removed under acidic conditions to participate in the synthesis of PROTAC molecules. Thalidomide -NH-PEG3-NH-Boc is a key intermediate in the synthesis of CRBN-based PROTAC molecules.