Used as an intermediate in the synthesis of peptide-based pharmaceuticals, specifically as a protected L-aspartic acid derivative (Cbz-Asp(OtBu)-OH) for solid-phase peptide synthesis. The benzyloxycarbonyl (Cbz) group protects the α-amino function, while the tert-butyl (tBu) ester safeguards the side-chain carboxylic acid, enabling selective deprotection and coupling reactions to construct complex peptide sequences with high purity and minimal side reactions. Commonly employed in research settings for developing protease inhibitors, antimicrobial agents, vaccines, and other bioactive molecules.