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Hydroacylation
Hydroacylation is a type of organic reaction in which an alkene is inserted into the a formyl C-H bond. The product is a ketone. The reaction requires a metal catalyst. It is almost invariably practiced as an intramolecular reaction using homogeneous catalysts, often based on rhodium phosphines. :RCHO + CH2=CHR' → RC(O)CH2CH2R' With an alkyne in place of alkenes, the reaction produce an α,β-unsaturated ketone. Examples The reaction was discovered as part of a synthetic route to certain prostanoids. The reaction required tin tetrachloride and a stoichiometric amount of Wilkinson's catalyst. An equal amount of a cyclopropane was formed as the result of decarbonylation. : The first catalytic application involved cyclization of 4-pentenal to cyclopentanone using with Wilkinson's catalyst. In this reaction the solvent was saturated with ethylene. :CH2=CHCH2CH2CHO → (CH2)4CO Reaction mechanism Labeling studies establish the following regiochemistry: :RCDO + CH2=CHR' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydroacylation ReactionMechanism
Hydroacylation is a type of organic reaction in which an alkene is inserted into the a formyl C-H bond. The product is a ketone. The reaction requires a metal catalyst. It is almost invariably practiced as an intramolecular reaction using homogeneous catalysts, often based on rhodium phosphines. :RCHO + CH2=CHR' → RC(O)CH2CH2R' With an alkyne in place of alkenes, the reaction produce an α,β-unsaturated ketone. Examples The reaction was discovered as part of a synthetic route to certain prostanoids. The reaction required tin tetrachloride and a stoichiometric amount of Wilkinson's catalyst. An equal amount of a cyclopropane was formed as the result of decarbonylation. : The first catalytic application involved cyclization of 4-pentenal to cyclopentanone using with Wilkinson's catalyst. In this reaction the solvent was saturated with ethylene. :CH2=CHCH2CH2CHO → (CH2)4CO Reaction mechanism Labeling studies establish the following regiochemistry: :RCDO + CH2=CHR' ... [...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] |
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] |
DuPhos
DuPhos is a class of organophosphorus compound that are used ligands for asymmetric synthesis. The name DuPhos is derived from (1) the chemical company that sponsored the research leading to this ligand's invention, DuPont and (2) the compound is a diphosphine ligand type. Specifically it is classified as a C2-symmetric ligand, consisting of two phospholanes rings affixed to a benzene ring. The ligand was introduced in 1991 by M.J. Burk and first demonstrated in asymmetric hydrogenation of certain enamide esters to amino acid precursors: : Other chiral diphosphine ligands were known at the time of invention, e.g. DIOP, DIPAMP, CHIRAPHOS, but DuPhos was found to be more effective. Description The ligand consists of two 2,5-alkyl-substituted phospholane rings connected by a 1,2-phenyl bridge. The alkyl group can be methyl, ethyl, propyl, or isopropyl. In the closely related bis(dimethylphospholano)ethane or BPE ligand the ''o''-phenylene bridge is replaced by a 1,2-ethylene bridg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diphosphine Ligand
Diphosphines, sometimes called bisphosphanes, are organophosphorus compounds most commonly used as bidentate phosphine ligand, phosphine ligands in inorganic chemistry, inorganic and organometallic chemistry. They are identified by the presence of two phosphino groups linked by a backbone, and are usually chelate, chelating. A wide variety of diphosphines have been synthesized with different linkers and R-groups. Alteration of the linker and R-groups alters the electronic and steric properties of the ligands which can result in different coordination geometries and catalytic behavior in Homogeneous catalysis, homogeneous catalysts. Synthesis image:IPr2PCl.png, 222px, Chlorodiisopropylphosphine is a popular building block for the preparation of diphosphines. From phosphide building blocks Many widely used diphosphine ligands have the general formula Ar2P(CH2)nPAr2. These compounds can be prepared from the reaction of X(CH2)nX (X=halogen) and MPPh2 (M = alkali metal): :Cl(CH2)nCl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhodium
Rhodium is a chemical element with the symbol Rh and atomic number 45. It is a very rare, silvery-white, hard, corrosion-resistant transition metal. It is a noble metal and a member of the platinum group. It has only one naturally occurring isotope: 103Rh. Naturally occurring rhodium is usually found as a free metal or as an alloy with similar metals and rarely as a chemical compound in minerals such as bowieite and rhodplumsite. It is one of the rarest and most valuable precious metals. Rhodium is found in platinum or nickel ores with the other members of the platinum group metals. It was discovered in 1803 by William Hyde Wollaston in one such ore, and named for the rose color of one of its chlorine compounds. The element's major use (consuming about 80% of world rhodium production) is as one of the catalysts in the three-way catalytic converters in automobiles. Because rhodium metal is inert against corrosion and most aggressive chemicals, and because of its rarity, rhodium ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrahedron (journal)
''Tetrahedron'' is a weekly peer-reviewed scientific journal covering the field of organic chemistry. According to the ''Journal Citation Reports'', ''Tetrahedron'' has a 2020 impact factor of 2.457. ''Tetrahedron'' and Elsevier, its publisher, support an annual symposium. In 2010, complaints were raised over its high subscription cost. Notable papers , the Web of Science lists ten papers from ''Tetrahedron'' that have more than 1000 citations. The four articles that have been cited more than 2000 times are: * – cited 2228 times * – cited 2162 times * – cited 2124 times * – cited 2107 times See also * ''Tetrahedron Letters'' * ''Tetrahedron Computer Methodology'' * ''Polyhedron In geometry, a polyhedron (plural polyhedra or polyhedrons; ) is a three-dimensional shape with flat polygonal faces, straight edges and sharp corners or vertices. A convex polyhedron is the convex hull of finitely many points, not all on th ...'' (journal) Refere ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asymmetric Reaction
Enantioselective synthesis, also called asymmetric synthesis, is a form of chemical synthesis. It is defined by IUPAC as "a chemical reaction (or reaction sequence) in which one or more new elements of chirality are formed in a substrate molecule and which produces the stereoisomeric ( enantiomeric or diastereomeric) products in unequal amounts." Put more simply: it is the synthesis of a compound by a method that favors the formation of a specific enantiomer or diastereomer. Enantiomers are stereoisomers that have opposite configurations at every chiral center. Diastereomers are stereoisomers that differ at one or more chiral centers. Enantioselective synthesis is a key process in modern chemistry and is particularly important in the field of pharmaceuticals, as the different enantiomers or diastereomers of a molecule often have different biological activity. Overview Many of the building blocks of biological systems such as sugars and amino acids are produced exclusive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metal Hydride
In chemistry, a hydride is formally the anion of hydrogen( H−). The term is applied loosely. At one extreme, all compounds containing covalently bound H atoms are called hydrides: water (H2O) is a hydride of oxygen, ammonia is a hydride of nitrogen, etc. For inorganic chemists, hydrides refer to compounds and ions in which hydrogen is covalently attached to a less electronegative element. In such cases, the H centre has nucleophilic character, which contrasts with the protic character of acids. The hydride anion is very rarely observed. Almost all of the elements form binary compounds with hydrogen, the exceptions being He, Ne, Ar, Kr, Pm, Os, Ir, Rn, Fr, and Ra. Exotic molecules such as positronium hydride have also been made. Bonds Bonds between hydrogen and the other elements range from highly to somewhat covalent. Some hydrides, e.g. boron hydrides, do not conform to classical electron-counting rules and the bonding is described in terms of multi-centered ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reductive Elimination
Reductive elimination is an elementary step in organometallic chemistry in which the oxidation state of the metal center decreases while forming a new covalent bond between two ligands. It is the microscopic reverse of oxidative addition, and is often the product-forming step in many catalytic processes. Since oxidative addition and reductive elimination are reverse reactions, the same mechanisms apply for both processes, and the product equilibrium depends on the thermodynamics of both directions. General information Reductive elimination is often seen in higher oxidation states, and can involve a two-electron change at a single metal center (mononuclear) or a one-electron change at each of two metal centers (binuclear, dinuclear, or bimetallic). For mononuclear reductive elimination, the oxidation state of the metal decreases by two, while the d-electron count of the metal increases by two. This pathway is common for d8 metals Ni(II), Pd(II), and Au(III) and d6 metals Pt(I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Migratory Insertion
In organometallic chemistry, a migratory insertion is a type of reaction wherein two ligands on a metal complex combine. It is a subset of reactions that very closely resembles the insertion reactions, and both are differentiated by the mechanism that leads to the resulting stereochemistry of the products. However, often the two are used interchangeably because the mechanism is sometimes unknown. Therefore, migratory insertion reactions or insertion reactions, for short, are defined not by the mechanism but by the overall regiochemistry wherein one chemical entity interposes itself into an existing bond of typically a second chemical entity e.g.: : + \longrightarrow Overview In the migratory insertion, a ligand that is viewed as an anion (X) ligand in and a ligand that is viewed as neutral couple, generating a new anionic ligand. The anion and neutral ligands that react are adjacent. If the precursor complex is coordinatively saturated, migratory insertion often result in a co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
