Used primarily in peptide synthesis, this chemical serves as a protected form of cysteine, ensuring the thiol group remains stable during the process. The tert-butylthio group protects the cysteine from unwanted reactions, while the Fmoc group allows for selective deprotection, enabling controlled peptide chain elongation. It is particularly valuable in solid-phase peptide synthesis (SPPS), where precise control over amino acid addition is crucial. This compound is also employed in the preparation of cysteine-containing peptides for research in biochemistry, drug development, and protein studies, where maintaining the integrity of the thiol group is essential for proper folding and function.