Used in peptide synthesis as a protected amino acid derivative, enabling the controlled assembly of complex peptides with defined stereochemistry. The Fmoc group allows for mild base deprotection, compatible with solid-phase synthesis, making it ideal for constructing sensitive or multifunctional peptides. The threo-beta-phenylserine moiety introduces structural diversity and can influence peptide conformation, stability, and biological activity. Commonly applied in the development of pharmaceuticals, enzyme inhibitors, and bioactive peptides where precise stereochemical control is critical.