Used primarily in peptide synthesis, this compound acts as a protecting group for cysteine residues. The Fmoc group ensures selective deprotection, while the Trt group shields the thiol functionality during the synthesis process. The pentafluorophenyl ester (Opfp) enhances reactivity, facilitating efficient coupling with amino acids. It is particularly valuable in solid-phase peptide synthesis, where precise control over cysteine incorporation is critical. Its application is essential in producing peptides with specific disulfide bonds, which are crucial for biological activity in therapeutic peptides and proteins.