Z-Ser-OBzl, also known as N-Carbobenzoxy-L-serine benzyl ester, is a protected derivative of the amino acid L-serine. It features two orthogonal protecting groups: the benzyloxycarbonyl (Cbz or Z) group on the amine and the benzyl (Bzl) ester on the carboxylic acid. This white to off-white crystalline solid is a fundamental building block in solid-phase and solution-phase peptide synthesis. Its primary application is as a key intermediate for the controlled incorporation of L-serine into peptide chains. The Cbz group is commonly removed under mild hydrogenolytic conditions, while the benzyl ester can be cleaved by hydrogenolysis or under acidic conditions, allowing for sequential deprotection strategies. This makes it essential for synthesizing peptides containing serine residues, which are often involved in phosphorylation sites and protein-protein interactions. While its main use is in peptide chemistry, it also serves as a versatile chiral synthon in organic synthesis due to its protected amine and ester functionalities. It is a standard reagent available from major suppliers of fine chemicals and peptide synthesis materials.