Thalidomide-O-PEG2-propargyl is primarily utilized in the field of medicinal chemistry and drug development, particularly in the design of targeted therapies. It serves as a key building block in the synthesis of PROTACs (Proteolysis Targeting Chimeras), which are bifunctional molecules designed to degrade specific disease-causing proteins. The propargyl group enables click chemistry reactions, facilitating the attachment of various functional groups or targeting moieties. This compound is also employed in the development of antibody-drug conjugates (ADCs), where it helps link cytotoxic agents to antibodies for precise cancer therapy. Additionally, its PEG (polyethylene glycol) spacer enhances solubility and stability, making it suitable for use in bioconjugation and drug delivery systems.