Used in peptide synthesis, particularly in solid-phase peptide synthesis (SPPS) methods. It serves as a protected amino acid derivative, where the Fmoc group ensures selective deprotection during peptide chain assembly. The 4-cyano substitution on the phenylalanine side chain introduces unique chemical properties, making it valuable in designing peptides with specific structural or functional characteristics. It is often employed in the development of bioactive peptides, enzyme inhibitors, and peptidomimetics for pharmaceutical research. The cyano group can also participate in further chemical modifications, enabling the creation of complex peptide-based molecules for drug discovery and biochemical studies.