Used in bioconjugation for the site-specific modification of biomolecules, particularly in the development of antibody-drug conjugates (ADCs) and peptide-based therapeutics. The Boc-protected aminooxy group allows for selective oxime ligation with aldehydes or ketones under mild acidic conditions, enabling stable linkage formation. The PEG2 spacer enhances solubility and reduces aggregation, while the terminal bromide permits further functionalization via nucleophilic substitution, such as with thiols or amines. Commonly employed in the synthesis of targeted drug delivery systems and diagnostic probes where controlled, multi-step conjugation is required.