(Boc-Cys-OH)₂ is the symmetrical disulfide dimer of N-Boc-cysteine, widely used in peptide synthesis as a protecting group for the thiol groups of cysteine residues. The Boc group protects the amino terminus, while the disulfide linkage safeguards the thiols against unwanted side reactions, such as oxidation or cross-linking, during peptide bond formation, ensuring the correct sequence and structure. This compound is particularly valuable in the synthesis of complex peptides and proteins. It is also employed in pharmaceutical production, especially for peptide-based drugs, where precise structural control is essential for efficacy and safety. Additionally, it finds applications in biochemical research for studying protein folding, disulfide bond formation, and enzyme activity.