Osmium tetroxide (also osmium(VIII) oxide) is the chemical compound with the formula OsO4. The compound is noteworthy for its many uses, despite its toxicity and the rarity of osmium. It also has a number of interesting properties, one being that the solid is volatile. The compound is colourless, but most samples appear yellow. This is most likely due to the presence of the impurity OsO2, which is yellow-brown in colour.
A diol is a chemical compound containing two hydroxyl groups. An aliphatic diol is also called a glycol. This pairing of functional groups is pervasive, and many subcategories have been identified.
In organic chemistry, AD-mix is a commercially available mixture of reagents that acts as an asymmetric catalyst for various chemical reactions, including the Sharpless asymmetric dihydroxylation of alkenes. The two letters AD, stand for asymmetric dihydroxylation. The mix is available in two variations, "AD-mix α" and "AD-mix β" following ingredient lists published by Barry Sharpless.
(E)-Stilbene, commonly known as trans-stilbene, is an organic compound represented by the condensed structural formula C6H5CH=CHC6H5. Classified as a diarylethene, it features a central ethylene moiety with one phenyl group substituents on each end of the carbon–carbon double bond. It has an (E) stereochemistry, meaning that the phenyl groups are located on opposite sides of the double bond, the opposite of its geometric isomer, cis-stilbene. Trans-stilbene occurs as a white crystalline solid at room temperature and is highly soluble in organic solvents. It can be converted to cis-stilbene photochemically, and further reacted to produce phenanthrene.
N-Methylmorpholine N-oxide (more correctly 4-methylmorpholine 4-oxide), NMO or NMMO is an organic compound. This heterocyclic amine oxide and morpholine derivative is used in organic chemistry as a co-oxidant and sacrificial catalyst in oxidation reactions for instance in osmium tetroxide oxidations and the Sharpless asymmetric dihydroxylation or oxidations with TPAP. NMO is commercially supplied both as a monohydrate C5H11NO2·H2O and as the anhydrous compound. The monohydrate is used as a solvent for cellulose in the Lyocell process to produce cellulose fibers.
The Upjohn Company was a pharmaceutical manufacturing firm founded in 1886 in Kalamazoo, Michigan, by Dr. William E. Upjohn, an 1875 graduate of the University of Michigan medical school. The company was originally formed to make friable pills, which were specifically designed to be easily digested. These could be "reduced to a powder under the thumb", a strong marketing argument at the time.
Dihydroxylation is the process by which an alkene is converted into a vicinal diol. Although there are many routes to accomplish this oxidation, the most common and direct processes use a high-oxidation-state transition metal. The metal is often used as a catalyst, with some other stoichiometric oxidant present. In addition, other transition metals and non-transition metal methods have been developed and used to catalyze the reaction.
The Jacobsen epoxidation, sometimes also referred to as Jacobsen-Katsuki epoxidation is a chemical reaction which allows enantioselective epoxidation of unfunctionalized alkyl- and aryl- substituted olefins. It is complementary to the Sharpless epoxidation (used to form epoxides from the double bond in allylic alcohols). The Jacobsen epoxidation gains its stereoselectivity from a C2 symmetric manganese(III) salen-like ligand, which is used in catalytic amounts. The manganese atom transfers an oxygen atom from chlorine bleach or similar oxidant. The reaction is named after its inventor, Eric Jacobsen, and sometimes also including Tsutomu Katsuki. Chiral-directing catalysts are useful to organic chemists trying to control the stereochemistry of biologically active compounds and develop enantiopure drugs.
The Shi epoxidation is a chemical reaction described as the asymmetric epoxidation of alkenes with oxone and a fructose-derived catalyst (1). This reaction is thought to proceed via a dioxirane intermediate, generated from the catalyst ketone by oxone. The addition of the sulfate group by the oxone facilitates the formation of the dioxirane by acting as a good leaving group during ring closure. It is notable for its use of a non-metal catalyst. The reaction was first discovered by Yian Shi of Colorado State University in 1996.
Ruthenium tetroxide (Ruthenium(VIII) oxide) is the inorganic compound with the formula RuO4. It is a colourless, diamagnetic liquid, but samples are typically black due to impurities. It is volatile. The analogous OsO4 is more widely used and better known. One of the few solvents in which it forms stable solutions is CCl4.
The Sharpless oxyamination is the chemical reaction that converts an alkene to a vicinal amino alcohol. A comprehensive review of this reaction was authored by McLeod et al. in 2002. Vicinal amino-alcohols are important products in organic synthesis and recurring pharmacophores in drug discovery.
Asymmetric catalytic oxidation is a technique of oxidizing various substrates to give an enantiopure product using a catalyst.
The Lemieux–Johnson or Malaprade–Lemieux–Johnson oxidation is a chemical reaction in which an olefin undergoes oxidative cleavage to form two aldehyde or ketone units. The reaction is named after its inventors, Raymond Urgel Lemieux and William Summer Johnson, who published it in 1956. The reaction proceeds in a two step manner, beginning with dihydroxylation of the alkene by osmium tetroxide, followed by a Malaprade reaction to cleave the diol using periodate. Excess periodate is used to regenerate the osmium tetroxide, allowing it to be used in catalytic amounts. The Lemieux–Johnson reaction ceases at the aldehyde stage of oxidation and therefore produces the same results as ozonolysis.
Jacobsen's catalyst is the common name for N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediaminomanganese(III) chloride, a coordination compound of manganese and a salen-type ligand. It is used as an asymmetric catalyst in the Jacobsen epoxidation, which is renowned for its ability to enantioselectively transform prochiral alkenes into epoxides. Prior to its development, catalysts for the asymmetric epoxidation of alkenes required the substrate to have a directing functional group, such as an alcohol as seen in the Sharpless epoxidation. This compound has two enantiomers, which give the appropriate epoxide product from the alkene starting material.
Oxoammonium-catalyzed oxidation reactions involve the conversion of organic substrates to more highly oxidized materials through the action of an N-oxoammonium species. Nitroxides may also be used in catalytic amounts in the presence of a stoichiometric amount of a terminal oxidant.
Nucleophilic epoxidation is the formation of epoxides from electron-deficient double bonds through the action of nucleophilic oxidants. Nucleophilic epoxidation methods represent a viable alternative to electrophilic methods, many of which do not epoxidize electron-poor double bonds efficiently.
A transition metal oxo complex is a coordination complex containing an oxo ligand. Formally O2-, an oxo ligand can be bound to one or more metal centers, i.e. it can exist as a terminal or (most commonly) as bridging ligands (Fig. 1). Oxo ligands stabilize high oxidation states of a metal.
