Used as a key intermediate in the synthesis of complex peptide-based pharmaceuticals, particularly in the development of targeted protein degraders such as PROTACs (proteolysis-targeting chimeras). Its functional groups allow for modular assembly by linking E3 ligase binders to target protein ligands, enabling selective degradation of disease-causing proteins. The tert-butoxycarbonyl (Boc) protecting groups provide stability during synthesis and can be selectively removed under mild acidic conditions, making it suitable for stepwise solid-phase or solution-phase peptide coupling. Its phenylacetic acid moiety serves as a linker with convenient handles for amide bond formation, enhancing conjugation efficiency in multi-component drug constructs. Widely applied in medicinal chemistry for optimizing pharmacokinetic properties and improving target specificity in oncology and neurodegenerative disease research.