Sharpless bishydroxylation or asymmetric dihydroxylation (AD) is a chemical reaction of an alkene with osmium tetroxide to form a diol (dialcohol). Chiral products can be formed by adding quinine derivatives. A more efficient way to perform this reaction is reoxidise the osmate, which is formed in the reaction, with potassium ferricyanide. This reduces the amount of the highly toxic and very expensive osmium tetroxide needed by up to 95%. It is possible to buy these mixtures as AD-mix α and AD-mix β. Jump to: navigation, search A chemical reaction is a process involving one, two or more substances (called reactants), characterized by a chemical change and yielding one or more product(s) which are different from the reactants. ... Jump to: navigation, search An alkene in organic chemistry is an unsaturated hydrocarbon containing at least one carbon to carbon double bond. ... The chemical compound osmium tetroxide (OsO4) is an oxide of the element osmium, in which it attains its highest oxidation number of 8. ... A diol is a chemical compound containing two hydroxyl groups. ... Jump to: navigation, search In general usage, alcohol (from Arabic al-ghawl الغول) refers almost always to ethanol, also known as grain alcohol, and often to any beverage that contains ethanol (see alcoholic beverage). ... In chemistry, a molecule is chiral if it is not superimposable on its mirror image regardless of how it is contorted. ... Jump to: navigation, search Molecular structure of quinine Tonic Water containing quinine. ... Jump to: navigation, search Potassium ferricyanide (K3Fe(CN)6), molecular weight:329. ... For a list of biologically injurious substances, including toxins and other materials, as well as their effects, see poison. ... AD-mix is a chiral ligand and stands for the Asymmetric dihydroxylation mix. ...

The chiral diols are important for further synthesis. The introduction of chirality (chemistry) into nonchiral reactants through small amounts of a chiral catalyst is an important concept in organic synthesis. In chemistry, a molecule is chiral if it is not superimposable on its mirror image regardless of how it is contorted. ... In chemistry, the reactants are the substances that exist at the start of a chemical reaction. ... Jump to: navigation, search A catalyst (Greek: καταλύτης, catalytēs) is a substance that accelerates the rate (speed) of a chemical reaction without itself being transformed or consumed by the reaction (see also catalysis). ... Organic synthesis is the construction of organic molecules via chemical processes. ...

This reaction was developed principally by K. Barry Sharpless, for which he was awarded a share of the 2001 Nobel Prize in Chemistry. Jump to: navigation, search Karl Barry Sharpless (born April 28, 1941) is an American chemist renowned for his work on organometallic chemistry. ... List of Nobel Prize laureates in Chemistry from 1901 to the present day. ...

Examples

The first step in the synthesis of azasugar 6 is a dihydroxylation reaction ^[1] of the prochiral diene 1. Azasugars are pharmacologically relevant. The entire reaction sequence takes place in water as a reaction medium and protective groups were not required. Notice the chemoselectivity in the nucleophilic substitution of bromine by the hydroxyl group in step 2. Image File history File links azasugar File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Refers to an atom in a molecule (usually a carbon atom) that would become chiral if one of two identical substituents is replaced by a new ligand; i. ... Dienes are hydrocarbons which contain two double bonds. ... A Protecting group or protective group is introduced into a molecule by chemical modification of a functional group in order to obtain chemoselectivity in a subsequent chemical reaction. ... A chemical reaction is said to posess chemoselectivity when one functional group is selectively attacked by a reagent in the presence of another functional group. ... Jump to: navigation, search In chemistry, nucleophilic substitution is a class of substitution reaction in which an electron-rich nucleophile attacks a molecule and replaces a group or atom, called the leaving group. ...

References

• ^[1] Efficient asymmetric synthesis of an azasugar in water Ulf M. Lindström, Rui Ding, Olle Hidestål Chemical Communications, 2005 p. 1773