Used as a key intermediate in the synthesis of pharmaceutical peptides, particularly in the development of protease inhibitors. The Boc (tert-butoxycarbonyl) group serves as a protecting group for the amino function, allowing selective reaction at other sites during peptide coupling. The 4-cyanophenyl moiety enhances structural rigidity and can influence binding affinity in biologically active molecules. Commonly employed in solid-phase peptide synthesis and in the preparation of enzyme inhibitors for research and drug development.