This compound, with CAS 401915-53-5, is a complex, multi-functional amino acid derivative. Its structure features an Fmoc-protected (3S)-diaminopropionic acid core, which is a common building block in solid-phase peptide synthesis (SPPS). The molecule is further elaborated with a 2,2,4,6,7-pentamethyl-2,3-dihydrobenzofuran-5-sulfonyl (Pbf-sulfonyl) group attached via a guanidino linkage. This Pbf-sulfonyl moiety is structurally analogous to established sulfonamide-based E3 ligase ligands, such as those targeting VHL or CRBN. The primary application of this compound is in the research and development of Proteolysis-Targeting Chimeras (PROTACs) and other targeted protein degradation modalities. It serves as a specialized linker molecule that incorporates both a peptide coupling handle (the Fmoc-protected amino acid) and a potential E3 ligase recruiting ligand (the Pbf-sulfonyl guanidine moiety). This design allows researchers to conjugate it to a target protein-binding warhead, facilitating the construction of heterobifunctional degraders. Its use is highly specialized within medicinal chemistry and chemical biology for probing ubiquitin-proteasome system pathways and creating novel therapeutic candidates. The presence of the Fmoc group makes it compatible with standard automated peptide synthesizers, enabling its modular incorporation into longer peptide-based or peptidomimetic degraders.