D-Leucine Ethyl Ester Hydrochloride is primarily used in peptide synthesis as a building block. It serves as a chiral intermediate in the production of various pharmaceutical compounds, particularly in the development of drugs targeting neurological and metabolic disorders. Its ester group makes it a useful precursor in organic synthesis, enabling the creation of complex molecules with high stereochemical purity. Additionally, it finds application in biochemical research as a substrate for studying enzyme mechanisms and protein interactions. Its hydrochloride form enhances solubility, making it suitable for use in aqueous reaction environments.