Bis[(+)-pinanediolato]diboron is a chiral diboron reagent, specifically a bis(pinacolato)diboron (B2pin2) derivative where the pinacol protecting group is replaced by the chiral (+)-pinanediol ligand. This substitution imparts chirality to the reagent, making it a valuable tool in asymmetric synthesis. Its primary and most significant application is in the highly enantioselective synthesis of chiral organoboron compounds. It serves as a key reagent in transition-metal-catalyzed asymmetric borylation reactions, such as the diboration of alkenes and alkynes. The resulting chiral 1,2-bis(boronate) esters or β-boryl compounds are versatile intermediates that can be further transformed into a wide array of enantiomerically enriched functional groups, including alcohols, amines, and halides, which are crucial building blocks in pharmaceutical and agrochemical research. The (+)-pinanediol auxiliary not only controls the stereochemistry of the borylation step but also often facilitates the purification and analysis of the resulting boronic esters due to their crystallinity. This reagent is a cornerstone in modern methodologies for constructing carbon-boron and carbon-carbon bonds with high enantioselectivity, underpinning its role as a specialized, high-value synthetic tool rather than a commodity chemical with a direct, singular end-use.