Used as a chiral building block in the synthesis of peptide-based pharmaceuticals, this is the benzyl ester of (S)-lysine dihydrochloride. The benzyl group protects the carboxyl functionality, enabling selective reactions at the alpha- and epsilon-amino groups, which are present as hydrochloride salts for improved stability and water solubility. Commonly employed in the development of antibiotics, enzyme inhibitors, antiviral agents, and protease inhibitors due to its similarity to the natural amino acid lysine. Its defined stereochemistry is essential for the biological activity of derived bioactive molecules, and it is suitable for applications requiring pH control and high purity.