Used in solid-phase peptide synthesis as an activated amino acid building block, enabling efficient and selective coupling to growing peptide chains. Its Fmoc protection allows for mild base deprotection, making it ideal for stepwise synthesis of complex peptides. Commonly applied in research settings for developing pharmaceuticals, biochemical probes, and custom peptides. The N-hydroxysuccinimide (OSu) ester group enhances coupling efficiency by reducing racemization and improving solubility in organic solvents.