O-tert-Butyl-D-threonine is a chiral, non-proteinogenic amino acid derivative. Its structure features a D-threonine backbone with the side-chain hydroxyl group protected by a tert-butyl ether group. This protection enhances its lipophilicity and stability, making it a valuable chiral building block in synthetic chemistry. This compound is primarily employed as a key chiral intermediate in the pharmaceutical industry for the synthesis of complex bioactive molecules. Its most notable application is in the production of certain peptide-based drugs and active pharmaceutical ingredients (APIs), where it introduces a specific stereocenter crucial for biological activity. The tert-butyl protecting group can be selectively removed under mild acidic conditions, allowing for further functionalization. As a protected form of D-threonine, it serves as a versatile synthon in asymmetric synthesis and peptide mimetics research. Its availability in high enantiomeric purity makes it essential for constructing stereochemically defined compounds in medicinal chemistry programs.