Used in peptide synthesis as a protecting group for amino acids, ensuring selective reactions during the formation of peptide bonds. It is particularly valuable in solid-phase peptide synthesis (SPPS) for its ability to provide stability and prevent unwanted side reactions. The Fmoc group can be easily removed under mild basic conditions, allowing for the stepwise construction of complex peptides. The PEG4 spacer enhances solubility and flexibility, facilitating better interaction with reagents and improving synthesis efficiency. The t-butyl acetate moiety offers additional protection for carboxyl groups, ensuring precise control over the chemical process. This compound is widely applied in the development of pharmaceuticals, bioactive peptides, and research involving protein engineering.