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Upjohn Dihydroxylation
The Upjohn dihydroxylation is an organic reaction which converts an alkene to a ''cis'' vicinal diol. It was developed by V. VanRheenen, R. C. Kelly and D. Y. Cha of the Upjohn Company in 1976. It is a catalytic system using ''N''-methylmorpholine ''N''-oxide (NMO) as stoichiometric re-oxidant for the osmium tetroxide. It is superior to previous catalytic methods. Prior to this method, use of stoichiometric amounts of the toxic and expensive reagent osmium tetroxide was often necessary. The Upjohn dihydroxylation is still often used for the formation of ''cis''-vicinal diols; however, it can be slow and is prone to ketone byproduct formation. One of the peculiarities of the dihydroxylation of olefins is that the standard "racemic" method (the Upjohn dihydroxylation) is slower and often lower yielding than the asymmetric method (the Sharpless asymmetric dihydroxylation). Improvements to Upjohn dihydroxylation In response to these problems, Stuart Warren and co-worke ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Upjohn
The Upjohn Company was a pharmaceutical manufacturing firm founded in 1886 in Hastings, Michigan, by Dr. William E. Upjohn who was 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. History Upjohn developed a process for the large scale production of cortisone. The oxygen atom at the 11 position in this steroid is an absolute requirement for biological activity. There are however no known natural sources for starting materials that contain that feature. The only method for preparing this drug prior to 1952 was a lengthy synthesis starting from cholic acid isolated from bile. In 1952, two Upjohn biochemists, Dury Peterson and Herb Murray announced that they were able to introduce this crucial oxygen atom by fermentation of the steroid progesterone with a comm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Reaction
Organic reactions are chemical reactions involving organic compounds. The basic organic chemistry reaction types are addition reactions, elimination reactions, substitution reactions, pericyclic reactions, rearrangement reactions, Mechanistic Organic Photochemistry, photochemical reactions and organic redox reaction, redox reactions. In organic synthesis, organic reactions are used in the construction of new organic molecules. The production of many man-made chemicals such as drugs, plastics, food additives, fabrics depend on organic reactions. The oldest organic reactions are combustion of organic fuels and saponification of fats to make soap. Modern organic chemistry starts with the Wöhler synthesis in 1828. In the history of the Nobel Prize in Chemistry awards have been given for the invention of specific organic reactions such as the Grignard reaction in 1912, the Diels-Alder reaction in 1950, the Wittig reaction in 1979 and olefin metathesis in 2005. Classifications Organic c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alkene
In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond. Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic, and Biological Chemistry'. 1232 pages. Two general types of monoalkenes are distinguished: terminal and internal. Also called α-olefins, terminal alkenes are more useful. However, the International Union of Pure and Applied Chemistry (IUPAC) recommends using the name "alkene" only for acyclic hydrocarbons with just one double bond; alkadiene, alkatriene, etc., or polyene for acyclic hydrocarbons with two or more double bonds; cycloalkene, cycloalkadiene, etc. for cyclic ones; and "olefin" for the general class – cyclic or acyclic, with one or more double bonds. Acyclic alkenes, with only one double bond and no other functional groups (also known as mono-enes) form a homologous series of hydrocarbons with the general formula with '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vicinal (chemistry)
In chemistry the descriptor vicinal (from Latin ''vicinus'' = neighbor), abbreviated ''vic'', describes any two functional groups bonded to two adjacent carbon atoms (i.e., in a 1,2-relationship). Relation of atoms in a molecule For example, the molecule 2,3-dibromobutane carries two vicinal bromine atoms and 1,3-dibromobutane does not. Mostly, the use of the term vicinal is restricted to two ''identical'' functional groups. Likewise in a ''gem-''dibromide the prefix ''gem'', an abbreviation of geminal, signals that both bromine atoms are bonded to the ''same'' atom (i.e., in a 1,1-relationship). For example, 1,1-dibromobutane is geminal. While comparatively less common, the term hominal has been suggested as a descriptor for groups in a 1,3-relationship. Like other such descriptors as syn, anti, exo or endo, the description ''vicinal'' helps explain how different parts of a molecule are related to each other either structurally or spatially. The vicinal adjective is sometim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diol
A diol is a chemical compound containing two hydroxyl groups ( groups). An aliphatic diol is also called a glycol. This pairing of functional groups is pervasive, and many subcategories have been identified. The most common industrial diol is ethylene glycol. Examples of diols in which the hydroxyl functional groups are more widely separated include 1,4-butanediol and propylene-1,3-diol, or beta propylene glycol, . Synthesis of classes of diols Geminal diols A geminal diol has two hydroxyl groups bonded to the same atom. These species arise by hydration of the carbonyl compounds. The hydration is usually unfavorable, but a notable exception is formaldehyde which, in water, exists in equilibrium with methanediol H2C(OH)2. Another example is (F3C)2C(OH)2, the hydrated form of hexafluoroacetone. Many gem-diols undergo further condensation to give dimeric and oligomeric derivatives. This reaction applies to glyoxal and related aldehydes. Vicinal diols In a vicinal diol, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Upjohn Company
The Upjohn Company was a pharmaceutical manufacturing firm founded in 1886 in Hastings, Michigan, by Dr. William E. Upjohn who was 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. History Upjohn developed a process for the large scale production of cortisone. The oxygen atom at the 11 position in this steroid is an absolute requirement for biological activity. There are however no known natural sources for starting materials that contain that feature. The only method for preparing this drug prior to 1952 was a lengthy synthesis starting from cholic acid isolated from bile. In 1952, two Upjohn biochemists, Dury Peterson and Herb Murray announced that they were able to introduce this crucial oxygen atom by fermentation of the steroid progesterone with a comm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrahedron Lett
''Tetrahedron Letters'' is a weekly international journal for rapid publication of full original research papers in the field of organic chemistry. According to the ''Journal Citation Reports'', the journal has a 2020 impact factor of 2.415. Indexing ''Tetrahedron Letters'' is indexed in: References See also *''Tetrahedron In geometry, a tetrahedron (plural: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular faces, six straight edges, and four vertex corners. The tetrahedron is the simplest of all the o ...'' *'' Tetrahedron: Asymmetry'' Chemistry journals Weekly journals Publications established in 1959 Elsevier academic journals {{chem-journal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
N-Methylmorpholine N-oxide
''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. Uses Solvent of cellulose NMMO monohydrate is used as a solvent in the lyocell process to produce lyocell fiber. It dissolves cellulose to form a solution called dope, and the cellulose is reprecipitated in a water bath to produce a fiber. The process is similar but not analogous to the viscose process. In the viscose process, cellulose is made soluble by conversion to its xanthate derivatives. With NMMO, cellul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Osmium Tetroxide
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 unusual 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. In biology, its property of binding to lipids has made it a widely-used stain in electron microscopy. Physical properties Osmium(VIII) oxide forms monoclinic crystals. It has a characteristic acrid chlorine-like odor. The element name osmium is derived from ''osme'', Greek for ''odor''. OsO4 is volatile: it sublimes at room temperature. It is soluble in a wide range of organic solvents. It is also moderately soluble in water, with which it reacts reversibly to form osmic acid (see below). ''Pure'' osmium(VIII) oxide is probably colourless and it has been sugg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Upjohn Dihydroxylation
The Upjohn dihydroxylation is an organic reaction which converts an alkene to a ''cis'' vicinal diol. It was developed by V. VanRheenen, R. C. Kelly and D. Y. Cha of the Upjohn Company in 1976. It is a catalytic system using ''N''-methylmorpholine ''N''-oxide (NMO) as stoichiometric re-oxidant for the osmium tetroxide. It is superior to previous catalytic methods. Prior to this method, use of stoichiometric amounts of the toxic and expensive reagent osmium tetroxide was often necessary. The Upjohn dihydroxylation is still often used for the formation of ''cis''-vicinal diols; however, it can be slow and is prone to ketone byproduct formation. One of the peculiarities of the dihydroxylation of olefins is that the standard "racemic" method (the Upjohn dihydroxylation) is slower and often lower yielding than the asymmetric method (the Sharpless asymmetric dihydroxylation). Improvements to Upjohn dihydroxylation In response to these problems, Stuart Warren and co-worke ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ketone
In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double bond C=O). The simplest ketone is acetone (where R and R' is methyl), with the formula . Many ketones are of great importance in biology and in industry. Examples include many sugars (ketoses), many steroids (e.g., testosterone), and the solvent acetone. Nomenclature and etymology The word ''ketone'' is derived from ''Aketon'', an old German word for ''acetone''. According to the rules of IUPAC nomenclature, ketone names are derived by changing the suffix ''-ane'' of the parent alkane to ''-anone''. Typically, the position of the carbonyl group is denoted by a number, but traditional nonsystematic names are still generally used for the most important ketones, for example acetone and benzophenone. These nonsystematic names are considere ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sharpless Asymmetric Dihydroxylation
Sharpless asymmetric dihydroxylation (also called the Sharpless bishydroxylation) is the chemical reaction of an alkene with osmium tetroxide in the presence of a chiral quinine ligand to form a vicinal diol. The reaction has been applied to alkenes of virtually every substitution, often high enantioselectivities are realized, with the chiral outcome controlled by the choice of dihydroquinidine (DHQD) vs dihydroquinine (DHQ) as the ligand. Asymmetric dihydroxylation reactions are also highly site selective, providing products derived from reaction of the most electron-rich double bond in the substrate. It is common practice to perform this reaction using a catalytic amount of osmium tetroxide, which after reaction is regenerated with reoxidants such as potassium ferricyanide or ''N''-methylmorpholine ''N''-oxide. This dramatically reduces the amount of the highly toxic and very expensive osmium tetroxide needed. These four reagents are commercially available premixed (" AD- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
