Used in peptide synthesis, particularly in solid-phase peptide synthesis (SPPS), as a building block for incorporating modified tyrosine residues into peptides. The Fmoc group protects the amino group during synthesis, while the ethyl modification on the tyrosine side chain can influence the peptide's properties, such as hydrophobicity or binding affinity. It is valuable in creating peptides for research in biochemistry, drug development, and molecular biology, especially where specific tyrosine modifications are required for functional studies or therapeutic applications.