(3S,4S)-3,4-Dihydroxypyrrolidine-1-carboxylic acid tert-butyl ester is a chiral, protected pyrrolidine derivative. It features a bicyclic pyrrolidine core with two cis-configured hydroxyl groups and a tert-butoxycarbonyl (Boc) protecting group on the nitrogen atom. This specific stereochemistry is crucial for its applications. This compound is a key chiral building block and pharmaceutical intermediate. Its primary application is in the synthesis of biologically active molecules, particularly iminosugars and glycosidase inhibitors. The cis-dihydroxylated pyrrolidine scaffold mimics sugar moieties and is a privileged structure in medicinal chemistry for developing treatments for metabolic disorders, viral infections (such as influenza and HIV), and certain types of cancer. As a versatile synthon, it is used to introduce a functionalized, nitrogen-containing heterocycle into target molecules. The Boc protecting group allows for selective deprotection and further functionalization of the amine nitrogen under mild conditions, making it a valuable reagent in multi-step organic synthesis for drug discovery programs.