Boc-D-Asp(OMe)-OH, with CAS number 137130-65-5, is a protected derivative of the natural amino acid D-aspartic acid. Its chemical structure features a tert-butoxycarbonyl (Boc) group protecting the alpha-amino functionality and a methyl ester protecting the beta-carboxylic acid side chain. This specific configuration renders it a non-natural, D-configured amino acid building block. This compound is primarily employed as a key chiral intermediate in the solid-phase and solution-phase synthesis of peptides and peptidomimetics. The use of D-amino acids, such as this derivative, is a common strategy in medicinal chemistry to enhance the metabolic stability, bioavailability, and biological activity profiles of therapeutic peptides by conferring resistance to proteolytic degradation. It is extensively used in research and development for creating peptide-based drug candidates, enzyme inhibitors, and biochemical probes. The Boc and methyl ester protecting groups are orthogonal to many other common protecting group strategies (like Fmoc), allowing for flexible synthetic routes. After incorporation into a peptide chain, these groups can be selectively removed under mild acidic conditions (Boc) and basic hydrolysis or hydrogenolysis (methyl ester), respectively, to reveal the free amino and carboxylic acid functionalities for further chain elongation or final deprotection.