Used as a chiral building block in the synthesis of pharmaceuticals, particularly in the development of protease inhibitors and other bioactive molecules. Its free thiol and protected amine (Boc) functionalities allow selective reactions at the thiol group and deprotection for coupling, making it valuable in peptide mimetics and drug design. Commonly employed in asymmetric synthesis to introduce stereochemical control. Also utilized in the preparation of cysteine analogs and in medicinal chemistry for constructing heterocyclic compounds with biological activity.