Fmoc-L-aspartic acid β-benzyl ester is widely used in peptide synthesis, particularly in solid-phase peptide synthesis (SPPS). It serves as a protected form of aspartic acid, where the Fmoc (fluorenylmethyloxycarbonyl) group protects the α-amino group, and the benzyl ester specifically protects the β-carboxylic acid group (side chain). This dual protection ensures selective reactions during peptide chain assembly, preventing unwanted side reactions such as aspartimide formation. The compound is especially valuable in synthesizing peptides with aspartic acid residues. After peptide synthesis, the Fmoc group is removed stepwise with base, while the benzyl ester can be cleaved under mild acidic or hydrogenolytic conditions during global deprotection, making it a versatile and essential reagent in the production of complex peptides for research, pharmaceuticals, and biotechnology applications.