(R)-BoroVal-(+)-Pinanediol-HCl is a specialized chemical building block featuring a boronic acid ester protected by (+)-pinanediol. The key structural element is the (R)-configured BoroVal moiety, which is a valine-derived boronic acid derivative. This compound is typically supplied as a hydrochloride salt to enhance its stability and handling properties. Its primary and most significant application is in the field of targeted protein degradation, specifically in the development of Proteolysis-Targeting Chimeras (PROTACs) and other bivalent degraders. The BoroVal group serves as a crucial warhead or ligand designed to bind to the catalytic threonine residue of the 20S proteasome. When incorporated into a PROTAC molecule via a linker, it recruits and brings the target protein into proximity with the proteasome, leading to its ubiquitin-independent degradation. This makes it a valuable "linker" component or a pre-functionalized synthon for constructing degraders. As a boronic acid ester derivative, it also falls under the category of organoboron reagents in synthetic chemistry. It is used as a precise synthetic intermediate for introducing the proteasome-binding pharmacophore into complex molecules, highlighting its role beyond a simple building block into a functionally critical component in modern drug discovery.