Thalidomide-O-PEG4-amine is primarily utilized in the development of PROTACs (Proteolysis Targeting Chimeras), which are innovative molecules designed to target and degrade specific proteins within cells. This compound serves as a key linker component, connecting the target protein-binding moiety to the E3 ubiquitin ligase-recruiting moiety. Its PEG4 spacer enhances solubility and flexibility, improving the efficiency of the PROTAC molecule in cellular environments. Additionally, it is employed in drug discovery and biochemical research to study protein degradation pathways and develop potential therapeutic agents for diseases like cancer, where targeting and eliminating specific proteins is crucial. Its application extends to the synthesis of bioconjugates, enabling the creation of novel compounds for targeted drug delivery systems.