Used primarily in peptide synthesis as a protected cysteine derivative, enabling selective and controlled assembly of complex peptides. The Boc (tert-butoxycarbonyl) group provides temporary protection of the amino group, while the 3,4-dimethylbenzyl moiety protects the thiol side chain, preventing unwanted oxidation or side reactions during coupling steps. This makes it especially valuable in solid-phase peptide synthesis and the preparation of biologically active peptides where cysteine residues are critical for structure or function. Its stability under various reaction conditions allows for high yields and purity in final products, commonly used in pharmaceutical research and development of therapeutic peptides.