N-Carbobenzoxy-L-threonine benzyl ester is a protected derivative of the amino acid L-threonine. It features two orthogonal protecting groups: a benzyloxycarbonyl (Cbz or Z) group on the amine and a benzyl (Bn) ester on the carboxylic acid. This dual protection renders the molecule a versatile and crucial building block in peptide synthesis, particularly for solid-phase and solution-phase methodologies. Its primary application is in the pharmaceutical industry as a key intermediate for the controlled incorporation of L-threonine into peptide sequences. The Cbz group can be removed under mild hydrogenolytic conditions, while the benzyl ester offers stability during peptide chain assembly and can be cleaved under specific conditions (e.g., hydrogenolysis, acidic treatment). This makes it essential for synthesizing therapeutic peptides, peptide hormones, and research peptides where the hydroxyl-containing side chain of threonine is required. The compound is a white to off-white crystalline powder. It must be stored under inert conditions to prevent degradation. As a specialty fine chemical, it is a critical reagent in medicinal chemistry and biochemical research for constructing complex biomolecules.