Used in bioconjugation and peptide synthesis, particularly for the site-specific modification of carbonyl-containing molecules such as aldehydes and ketones. Its aminooxy group reacts selectively with carbonyl groups to form stable oxime bonds, enabling efficient ligation under mild conditions. The Fmoc group allows for standard solid-phase peptide synthesis strategies, facilitating the incorporation into larger peptide sequences. The PEG2 spacer improves solubility and reduces steric hindrance, enhancing reaction efficiency and biocompatibility. Commonly applied in the development of peptide-protein conjugates, antibody-drug conjugates (ADCs), and functionalized biomaterials for research and therapeutic purposes.