Used in solid-phase peptide synthesis as a protected cysteine derivative, enabling selective disulfide bond formation in complex peptide structures. The trityl group protects the thiol functionality, offering high stability during Fmoc deprotection steps, while allowing selective deprotection under mild acidic conditions. This makes it valuable for synthesizing peptides with multiple disulfide bridges, such as conotoxins and other bioactive peptides. The Fmoc group ensures compatibility with standard peptide coupling protocols, facilitating stepwise assembly on resin. Its stereochemistry ensures correct chiral configuration in the final peptide product, critical for biological activity.