This is a protected dipeptide building block, specifically N-Fmoc-L-phenylalanyl-N^α-Boc-L-lysyl-(4-hydroxymethylanilide), used in the synthesis of complex peptides and bioactive molecules. The Fmoc group on the phenylalanine nitrogen enables orthogonal deprotection under mild basic conditions (e.g., piperidine), facilitating incorporation into solid-phase or solution-phase peptide synthesis while maintaining stereochemical integrity. The Boc-protected lysine side chain provides selective protection for the ε-amine, and the C-terminal amide linked to 4-(hydroxymethyl)phenyl serves as a functional handle for further derivatization or conjugation. It is particularly valuable in pharmaceutical research for constructing enzyme inhibitors, such as protease inhibitors, and other therapeutics requiring precise control over peptide assembly and high purity.