This compound, N-[(9H-Fluoren-9-ylmethoxy)carbonyl]-4-{[(4S)-2,6-dioxohexahydropyrimidine-4-carbonyl]amino}-L-phenylalanine, is a specialized Fmoc-protected building block derived from a modified phenylalanine. It is widely used in solid-phase peptide synthesis (SPPS) to incorporate this non-natural amino acid residue into peptide chains, preventing unwanted side reactions via the Fmoc protecting group on the α-amino function. The Fmoc is selectively removed under mild basic conditions (e.g., with piperidine), facilitating stepwise peptide assembly. This reagent is crucial for producing complex peptides and proteins with high purity and specificity in research, pharmaceuticals, and biotechnology. It supports the development of peptide-based drugs, therapeutic agents, and biomaterials by enabling precise structural modifications.