N-[tert-Butoxycarbonyl]-3-[[benzyloxycarbonyl]amino]-D-alanine is a protected D-amino acid derivative. It features two orthogonal protecting groups: a tert-butoxycarbonyl (Boc) group on the α-amino function and a benzyloxycarbonyl (Cbz or Z) group on the side-chain amino group. This specific configuration makes it a chiral, orthogonally protected building block. This compound is primarily used as a key intermediate in the solid-phase and solution-phase synthesis of complex peptides and peptidomimetics. The presence of the D-alanine stereochemistry is crucial for constructing peptides with specific secondary structures, enhanced metabolic stability, or resistance to enzymatic degradation, which are important in the development of therapeutic peptides and bioactive probes. Its well-defined protection strategy allows for selective deprotection under mild conditions (e.g., acidic for Boc, hydrogenolysis for Cbz), facilitating sequential peptide chain elongation. It is a specialized reagent in medicinal chemistry and chemical biology research for creating peptide libraries and investigating structure-activity relationships.