Used as a key chiral intermediate in the synthesis of pharmaceutical compounds, particularly in the development of protease inhibitors and other biologically active molecules. The N-Boc group protects the nitrogen, while the free carboxylic acid and methanesulfonyloxy (mesylate) at the 4-position allow selective reactions at specific sites, making it valuable in multi-step organic syntheses. The mesylate group serves as a good leaving group, enabling nucleophilic substitution reactions to introduce various side chains, such as carbon-carbon or carbon-nitrogen bonds. Commonly employed in the preparation of peptide mimetics and cyclic amino acid derivatives for drug discovery research.