Used as a chiral auxiliary in asymmetric synthesis, particularly in the preparation of enantiomerically pure amines and amino acids. Its steric and electronic properties help control stereochemistry during nucleophilic addition reactions, especially in the synthesis of complex pharmaceutical intermediates. Commonly employed in the Ellman asymmetric synthesis, enabling high diastereoselectivity when reacting with organometallic reagents like Grignard or organolithium compounds. After serving its purpose, the auxiliary can be cleaved under mild acidic conditions, leaving the desired chiral amine intact. Widely applied in the development of active pharmaceutical ingredients (APIs) where stereochemical purity is critical.