(S)-tert-Butyl α-hydroxyisovalerate is a chiral organic compound featuring a tert-butyl ester group and an α-hydroxy acid structure. It is a key chiral building block in organic synthesis, particularly valued for its (S)-configuration at the stereogenic center. Its primary application is as a crucial chiral intermediate in the synthesis of various pharmaceuticals. It is notably used in the production of angiotensin-converting enzyme (ACE) inhibitors, such as benazepril and related drugs, where the (S)-configuration is essential for biological activity. The tert-butyl ester group serves as a common protecting group for carboxylic acids, facilitating subsequent synthetic steps. This compound is a versatile synthon for introducing the (S)-2-hydroxy-3-methylbutanoic acid moiety into target molecules. It is commercially available from suppliers specializing in fine chemicals and chiral intermediates for medicinal chemistry and process development.