(S)-3-((((9H-Fluoren-9-yl)methoxy)carbonyl)amino)-3-(2-methoxyphenyl)propanoic acid is a non-natural amino acid derivative. Its structure features a (S)-configured chiral center bearing a 2-methoxyphenyl side chain, a carboxylic acid group, and an amino group protected by the 9-fluorenylmethoxycarbonyl (Fmoc) group. The CAS number 501015-28-7 is associated with this specific compound. This compound is primarily used as a specialized building block in solid-phase peptide synthesis (SPPS). The Fmoc protecting group on the amino terminus is standard for Fmoc-based SPPS protocols, allowing for orthogonal deprotection under mild basic conditions. The unique 2-methoxyphenyl side chain introduces specific steric, electronic, and hydrophobic properties into the peptide sequence, making it valuable for medicinal chemistry research. It is employed in the synthesis of peptide analogs, peptidomimetics, and bioactive peptides to study structure-activity relationships (SAR), modulate peptide stability, or confer novel biological activities. As a research-grade chemical, it is supplied by fine chemical and life science reagent vendors for use in pharmaceutical R&D. Handling requires standard precautions for laboratory chemicals.