Thalidomide-NH-PEG3-NH-Boc is an E3 Ligase Ligand-Linker Conjugate consisting of Thalidomide (HY-14658) 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.