Widely used in peptide synthesis as a protected derivative of D-aspartic acid, with the Fmoc group on the alpha-amino group and t-butyl (OtBu) ester on the side chain carboxyl, ensuring selective reactions during the assembly of peptide chains. The Fmoc group is easily removed under mild basic conditions, making it suitable for solid-phase peptide synthesis (SPPS). The pentafluorophenyl (Opfp) ester enhances reactivity, facilitating efficient coupling with amino groups. Commonly employed in the production of complex peptides and proteins for pharmaceutical research, including drug development and biochemical studies. Its stability and reactivity make it a preferred choice in automated peptide synthesizers.