Used as a key chiral intermediate in the synthesis of pharmaceuticals, particularly in the development of protease inhibitors and antiviral drugs. Its structural features allow for selective binding and improved metabolic stability in active compounds. Commonly employed in the preparation of hepatitis C virus (HCV) NS3/4A protease inhibitors due to its ability to enhance potency and pharmacokinetic properties. The hydrochloride salt form improves solubility and handling during manufacturing processes. Also utilized in research settings for building complex heterocyclic systems in medicinal chemistry.