Used as a protected intermediate in the synthesis of pharmaceutical compounds, particularly in the development of peptide-based drugs. The tert-butoxycarbonyl (Boc) group provides temporary protection for the amine functionality, while the methyl ester masks the carboxylic acid, allowing selective reactions at other sites. The hydroxyl group on the proline ring can be further modified for structure-activity studies. Commonly employed in multi-step organic syntheses where stereochemical integrity is crucial, especially in the preparation of protease inhibitors and other bioactive molecules. Its stability under various reaction conditions makes it suitable for solid-phase and solution-phase peptide coupling strategies.