Used in peptide synthesis as an activated ester for introducing the Boc-protected norleucine amino acid residue. Enables efficient coupling under mild conditions, minimizing racemization. Commonly applied in solid-phase and solution-phase peptide assembly. The Boc group provides acid-labile protection, allowing selective deprotection in multi-step syntheses. Stable under standard handling conditions, making it suitable for automated peptide synthesizers. Also utilized in the preparation of enzyme substrates, inhibitors, and bioconjugates where a non-natural amino acid analog is required.