(3R,4R)-3-Amino-4-hydroxypyrrolidine-1-carboxylic acid tert-butyl ester is a chiral, bicyclic amino alcohol derivative. It features a pyrrolidine ring core substituted with both an amino group and a hydroxyl group at the 3- and 4-positions, respectively, with defined (3R,4R) stereochemistry. The nitrogen atom is protected by a tert-butoxycarbonyl (Boc) group, a common strategy in peptide and medicinal chemistry to modulate reactivity and solubility. This compound is a crucial and versatile chiral building block in pharmaceutical synthesis. Its primary application is as a key intermediate in the production of neuraminidase inhibitors, a class of antiviral drugs. Most notably, it is a critical precursor in the synthesis of Zanamivir (Relenza®), an anti-influenza medication. The (3R,4R) stereochemistry of the amino and hydroxyl groups is essential for the biological activity of the final drug molecule, mimicking the transition state of sialic acid cleavage. As a Boc-protected, multifunctional chiral scaffold, it is also valuable for constructing other complex molecules, particularly those containing pyrrolidine or proline-like motifs. Its stability under the Boc protecting group allows for selective manipulation of the amino and hydroxyl functionalities during multi-step synthetic sequences targeting bioactive compounds.