Used primarily in peptide synthesis as a protected serine derivative, featuring Fmoc protection on the amino group and a propyl ether on the side chain hydroxyl group. This dual protection enables selective coupling reactions while keeping the side chain stable and non-reactive. The Fmoc group provides mild base-labile deprotection, ideal for solid-phase peptide synthesis (SPPS). The (S)-configuration maintains stereochemical integrity for producing biologically active peptides. Commonly used in pharmaceutical research and development of peptide-based therapeutics.