This compound is the Fmoc-protected derivative of (S)-2-amino-3-(naphthalen-1-yl)propanoic acid, commonly known as Fmoc-(S)-Nal-OH or Fmoc-1-naphthylalanine. It serves as a key building block in solid-phase peptide synthesis (SPPS) for incorporating the non-natural naphthylalanine residue into peptide chains. The fluorenylmethoxycarbonyl (Fmoc) group protects the α-amino function, enabling orthogonal deprotection with mild bases like piperidine while preventing side reactions during coupling steps. The naphthalene moiety in the side chain imparts enhanced hydrophobicity, UV absorbance for monitoring, stability, and solubility in organic solvents, making it suitable for synthesizing peptides with modified properties. After assembly, the Fmoc group is selectively removed to reveal the free amino terminus. This specialty reagent is essential for pharmaceutical research, drug development, and biochemical studies involving bioactive peptides.