This compound, tert-Butyl (S)-(1-amino-1-oxo-3-phenylpropan-2-yl)carbamate, also known as Boc-L-phenylalaninamide, is a protected amino acid derivative used as a building block in peptide synthesis. The Boc (tert-butoxycarbonyl) group protects the N-terminal amino group of L-phenylalanine, while the C-terminus is amidated. It is particularly valuable in solid-phase peptide synthesis (SPPS) for incorporating phenylalanine residues at the C-terminal end of peptides with an amide functionality. This intermediate is crucial for the synthesis of peptide-based pharmaceuticals and research into bioactive peptides, enzyme inhibitors, and receptor ligands. The Boc protection enables selective deprotection under acidic conditions, allowing precise stepwise assembly of peptide chains while maintaining stability during coupling reactions.