Thalidomide-5-PEG2-Cl is primarily utilized in the development of PROTACs (Proteolysis Targeting Chimeras), a cutting-edge technology in drug discovery. It serves as a key linker component, connecting the target protein-binding moiety to the E3 ubiquitin ligase recruiter. This facilitates the targeted degradation of specific proteins, offering a novel approach to treating diseases like cancer, neurodegenerative disorders, and autoimmune conditions. Its application is particularly valuable in cases where traditional inhibitors fail to effectively modulate protein function. Additionally, it is used in research to study protein-protein interactions and cellular pathways, contributing to the understanding of disease mechanisms and the development of targeted therapies.