Used in bioconjugation and pharmaceutical research, this compound serves as a bifunctional linker that combines the reactivity of a propargyl group with the protective stability of a Boc-protected amine. The PEG4 spacer enhances water solubility and provides flexibility, making it ideal for constructing antibody-drug conjugates (ADCs), peptide modifications, and surface immobilization in diagnostic assays. Its propargyl end readily participates in copper-catalyzed azide-alkyne cycloaddition (CuAAC) click chemistry, enabling efficient ligation with azide-containing molecules. The Boc-protected amine allows for controlled deprotection and subsequent coupling to carboxylic acids or other electrophiles, facilitating stepwise synthesis in complex molecular architectures. Widely applied in drug discovery and biomaterial development where precise molecular spacing and selective reactivity are critical.