This compound is the Fmoc-protected derivative of (S)-O-methylserine, specifically (S)-2-((((9H-Fluoren-9-yl)methoxy)carbonyl)amino)-3-methoxypropanoic acid. It is primarily used in solid-phase peptide synthesis (SPPS) as a building block for incorporating O-methylserine residues into peptides. The fluorenylmethoxycarbonyl (Fmoc) group serves as an amino protecting group, preventing unwanted reactions during the controlled, stepwise assembly of peptides. The methoxy group on the serine side chain enhances solubility in organic solvents and stability. After peptide assembly, the Fmoc group is removed under mild basic conditions (e.g., with piperidine), preserving the peptide integrity. This reagent is essential for producing pharmaceuticals, research peptides, and bioactive molecules requiring modified serine residues.