D-Alanine benzyl ester p-toluenesulfonate salt is primarily used in peptide synthesis as a protecting group for the carboxyl group of D-alanine. This compound helps in the selective formation of peptide bonds by preventing unwanted reactions at the carboxyl site during the synthesis process. It is particularly valuable in the production of complex peptides and proteins, where precise control over the sequence and structure is essential. Additionally, it finds application in the preparation of chiral compounds and in pharmaceutical research for developing drugs with specific stereochemical properties. Its stability and ease of removal make it a preferred choice in organic synthesis and biochemical studies.