Widely used in peptide synthesis as a protected amino acid derivative, enabling selective coupling reactions without side-chain interference. The Boc (tert-butoxycarbonyl) group provides reversible protection of the amine functionality, allowing stepwise assembly of complex peptides. The 4-nitrophenyl group enhances crystallinity and aids in monitoring reaction progress through color changes during deprotection or coupling. Commonly employed in solid-phase and solution-phase peptide synthesis for pharmaceutical and biochemical research.