AD-mix α

Other names: (DHQ)₂PHAL, bis(dihydroquinine)phthalazine

C₄₈H₅₄N₆O₄

20/50 common

AD-mix α is a premixed reagent system developed by K. Barry Sharpless for asymmetric dihydroxylation of olefins, earning him part of the 2001 Nobel Prize in Chemistry. This powerful mixture contains potassium osmate, potassium ferricyanide, and the chiral ligand (DHQ)₂PHAL (derived from dihydroquinine and phthalazine), which directs the delivery of hydroxyl groups to the "α-face" of alkenes with remarkable enantioselectivity. AD-mix α appears as a pale yellow powder that reacts with olefins in a biphasic solvent system to produce vicinal diols with predictable stereochemistry, often achieving >99% enantiomeric excess. Its complementary reagent, AD-mix β, contains the pseudoenantiomeric ligand (DHQD)₂PHAL and hydroxylates the opposite face of the alkene. This reagent's practical simplicity and excellent stereocontrol have made it indispensable in natural product synthesis and pharmaceutical development, where precise control of stereochemistry is essential.