Fmoc-β-Ala-Asp(OMpe)-OH is a specialized amino acid derivative employed in solid-phase peptide synthesis (SPPS). It is composed of a β-alanine spacer and an aspartic acid residue, with the β-carboxyl group protected by a 3-methylpentyl ester (OMpe) to prevent aspartimide formation during synthesis. This compound serves as a valuable building block for synthesizing peptides containing aspartic acid, as the OMpe group is specifically designed to minimize unwanted side reactions.