L-Leucine benzyl ester p-toluenesulfonate salt is primarily used in organic synthesis and peptide chemistry. It serves as a protected form of L-leucine, where the benzyl ester group safeguards the carboxyl functionality during chemical reactions. This compound is particularly valuable in the synthesis of peptides, enabling the stepwise construction of complex peptide chains without unwanted side reactions. It is also employed in the preparation of modified amino acids and as an intermediate in the development of pharmaceuticals. Additionally, its tosylate salt form enhances solubility and stability, making it suitable for various reaction conditions in laboratory settings.