Widely used in peptide synthesis, this compound serves as a chiral building block for introducing protected aspartic acid derivatives with high stereochemical purity. Its Fmoc group allows for mild base-labile protection, making it compatible with solid-phase peptide synthesis (SPPS). The tert-butyl ester offers orthogonal protection for the side chain carboxylic acid, enabling selective deprotection under acidic conditions without affecting the Fmoc group. This dual protection strategy is essential for the stepwise assembly of complex peptides, especially in pharmaceutical research and development of bioactive molecules.