This compound, (S)-(9H-Fluoren-9-yl)methyl (1-oxopropan-2-yl)carbamate, is the Fmoc-protected derivative of L-alaninal. It serves as a key building block in advanced peptide synthesis, particularly for incorporating an aldehyde group at the C-terminus of peptides. The Fmoc protecting group safeguards the N-terminal amino function, enabling orthogonal deprotection and selective coupling in solid-phase or solution-phase methodologies. This reagent is essential for synthesizing peptide aldehydes used in native chemical ligation, protease inhibitor development, and bioactive molecule construction. Its stability and compatibility with standard synthesis protocols make it invaluable in biochemical research and medicinal chemistry for creating complex peptide-based therapeutics.