(S)-2-Aminosuccinic acid diallyl ester 4-methylbenzenesulfonate is a chiral organic salt. It features a protected (S)-2-aminosuccinic acid (aspartic acid) core, with the carboxylic acid groups esterified as diallyl esters and the amine group as a tosylate salt. This specific protection pattern renders it a valuable chiral building block. This compound is primarily utilized as a key chiral intermediate in the synthesis of complex pharmaceutical molecules. The (S)-aspartic acid backbone is a common motif in bioactive compounds, and the diallyl ester protecting groups offer orthogonal deprotection strategies, facilitating further synthetic elaboration. Its main application lies in the research and development of peptide mimetics and other drug candidates where precise stereochemistry is crucial for biological activity. As a protected amino acid derivative, it serves as a specialized synthon in medicinal chemistry. The tosylate salt form enhances its stability and crystallinity, making it suitable for handling and storage in laboratory settings.