Used in peptide synthesis as a protected amino acid derivative, enabling selective coupling in solid-phase and solution-phase peptide assembly. The Boc group protects the amine, while the methyl ester shields the C-terminal carboxyl, allowing stepwise construction of complex peptides. Commonly applied in pharmaceutical research for developing peptide-based drugs, especially where methionine and leucine residues are required. Stable under various reaction conditions, it supports efficient deprotection and chain elongation without side reactions.