Used in peptide synthesis as a chiral building block for incorporating propargyl-modified serine derivatives into peptides. The Fmoc group allows for solid-phase synthesis using standard Fmoc-strategy, while the propargyloxy side chain enables click chemistry modifications, such as copper-catalyzed azide-alkyne cycloaddition (CuAAC), for peptide conjugation, labeling, or immobilization. The (S)-configuration ensures stereochemical compatibility with natural amino acids, making it valuable in the design of bioactive peptides, peptidomimetics, and functional biomaterials.