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Mukaiyama Aldol Addition
The Mukaiyama aldol addition is an organic reaction and a type of aldol reaction between a silyl enol ether and an aldehyde or formate. The reaction was discovered by Teruaki Mukaiyama (1927–2018) in 1973. His choice of reactants allows for a crossed aldol reaction between an aldehyde and a ketone or a different aldehyde without self-condensation of the aldehyde. For this reason the reaction is used extensively in organic synthesis. General reaction scheme The Mukaiyama aldol addition is a Lewis acid mediated addition of enol silanes to carbonyl compounds. In this reaction compounds with various organic groups can be used (see educts). A basic version ( = H) without the presence of chiral catalysts is shown below. A racemic mix of enantiomers is built. If Z- or E-enol silanes are used in this reaction a mixture of four products occurs, yielding two racemates. Whether the ''anti''-diastereomer or the ''syn''-diastereomer is built depends largely on reaction conditions, sub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mukaiyama Aldehyde V1
was a Japanese organic chemist. One of the most prolific chemists of the 20th century in the field of organic synthesis, Mukaiyama helped establish the field of organic chemistry in Japan after World War II. Education Mukaiyama studied chemistry at the Tokyo Institute of Technology, earning his BSc in synthetic organic chemistry in 1948. He became assistant professor at Gakushuin University in 1953, where he stayed until he received his Ph.D. in synthetic organic chemistry from the University of Tokyo in 1957. Research and career Early work Mukaiyama became an assistant professor at the Tokyo Institute of Technology in 1958 and earned his full professorship in 1963. During this time, his main focus was on organophosphorus chemistry. While examining deoxygenation reactions involving phosphines, Mukaiyama found that the mercury(II) acetate employed as a catalyst would react with phosphorus(III) compounds to produce acetic anhydride. This initial example expanded into the concept o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diastereomeric
In stereochemistry, diastereomers (sometimes called diastereoisomers) are a type of stereoisomer. Diastereomers are defined as non-mirror image, non-identical stereoisomers. Hence, they occur when two or more stereoisomers of a compound have different configurations at one or more (but not all) of the equivalent (related) stereocenters and are not mirror images of each other. When two diastereoisomers differ from each other at only one stereocenter, they are epimers. Each stereocenter gives rise to two different configurations and thus typically increases the number of stereoisomers by a factor of two. Diastereomers differ from enantiomers in that the latter are pairs of stereoisomers that differ in all stereocenters and are therefore mirror images of one another. Enantiomers of a compound with more than one stereocenter are also diastereomers of the other stereoisomers of that compound that are not their mirror image (that is, excluding the opposing enantiomer). Diastereomers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Georg Wittig
Georg Wittig (; 16 June 1897 – 26 August 1987) was a German chemist who reported a method for synthesis of alkenes from aldehydes and ketones using compounds called phosphonium ylides in the Wittig reaction. He shared the Nobel Prize in Chemistry with Herbert C. Brown in 1979. Biography Wittig was born in Berlin, Germany and shortly after his birth moved with his family to Kassel, where his father was professor at the applied arts high school. He attended school in Kassel and started studying chemistry at the University of Tübingen 1916. He was drafted and became a lieutenant in the cavalry of Hesse-Kassel (or Hesse-Cassel). After being an Allied prisoner of war from 1918 until 1919, Wittig found it hard to restart his chemistry studies owing to overcrowding at the universities. By a direct plea to Karl von Auwers, who was professor for organic chemistry at the University of Marburg at the time, he was able to resume university study and after 3 years was awarded the Ph.D. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Syntheses
''Organic Syntheses'' is a peer-reviewed scientific journal that was established in 1921. It publishes detailed and checked procedures for the synthesis of organic compounds. A unique feature of the review process is that all of the data and experiments reported in an article must be successfully repeated in the laboratory of a member of the editorial board as a check for reproducibility prior to publication. The journal is published by Organic Syntheses, Inc., a non-profit corporation. An annual print version is published by John Wiley & Sons on behalf of Organic Syntheses, Inc. History Prior to World War I, work on synthetic organic chemistry in the United States had been quite limited, and most of the reagents used in laboratories had to be imported from Europe. When export stoppages and trade embargoes cut off this source, Clarence Derick, a professor of chemistry at University of Illinois at Urbana-Champaign, began an effort to synthesize these needed chemicals in industr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acetone
Acetone (2-propanone or dimethyl ketone), is an organic compound with the formula . It is the simplest and smallest ketone (). It is a colorless, highly volatile and flammable liquid with a characteristic pungent odour. Acetone is miscible with water and serves as an important organic solvent in its own right, in industry, home, and laboratory. About 6.7 million tonnes were produced worldwide in 2010, mainly for use as a solvent and production of methyl methacrylate (and from that PMMA) as well as bisphenol A.Acetone World Petrochemicals report, January 2010Stylianos Sifniades, Alan B. Levy, "Acetone" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005. It is a common building block in |
Acetophenone
Acetophenone is the organic compound with the formula C6H5C(O)CH3. It is the simplest aromatic ketone. This colorless, viscous liquid is a precursor to useful resins and fragrances. Production Acetophenone is formed as a byproduct of the cumene process, the industrial route for the synthesis of phenol and acetone. In the Hock rearrangement of isopropylbenzene hydroperoxide, migration of a methyl group rather than the phenyl group gives acetophenone and methanol as a result of an alternate rearrangement of the intermediate: :C6H5C(CH3)2O2H -> C6H5C(O)CH3 + CH3OH The cumene process is conducted on such a large scale that even the small amount of acetophenone by-product can be recovered in commercially useful quantities. Acetophenone is also generated from ethylbenzene hydroperoxide. Ethylbenzene hydroperoxide is primarily converted to 1-phenylethanol (α-methylbenzyl alcohol) in the process with a small amount of by-product acetophenone. Acetophenone is recovered or hydrogena ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mukaiyama Aldol-MechanismusV7 En
was a Japanese organic chemist. One of the most prolific chemists of the 20th century in the field of organic synthesis, Mukaiyama helped establish the field of organic chemistry in Japan after World War II. Education Mukaiyama studied chemistry at the Tokyo Institute of Technology, earning his BSc in synthetic organic chemistry in 1948. He became assistant professor at Gakushuin University in 1953, where he stayed until he received his Ph.D. in synthetic organic chemistry from the University of Tokyo in 1957. Research and career Early work Mukaiyama became an assistant professor at the Tokyo Institute of Technology in 1958 and earned his full professorship in 1963. During this time, his main focus was on organophosphorus chemistry. While examining deoxygenation reactions involving phosphines, Mukaiyama found that the mercury(II) acetate employed as a catalyst would react with phosphorus(III) compounds to produce acetic anhydride. This initial example expanded into the concept ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asymmetric Synthesis
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 exclusively as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Titanium Tetrachloride
Titanium tetrachloride is the inorganic compound with the formula . It is an important intermediate in the production of titanium metal and the pigment titanium dioxide. is a volatile liquid. Upon contact with humid air, it forms thick clouds of titanium dioxide () and hydrochloric acid, a reaction that was formerly exploited for use in smoke machines. It is sometimes referred to as "tickle" or "tickle 4" due to the phonetic resemblance of its molecular formula () to the word. Properties and structure is a dense, colourless distillable liquid, although crude samples may be yellow or even red-brown. It is one of the rare transition metal halides that is a liquid at room temperature, being another example. This property reflects the fact that molecules of weakly self-associate. Most metal chlorides are polymers, wherein the chloride atoms bridge between the metals. Its melting and boiling points are similar to those of . has a "closed" electronic shell, with the same numbe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aldol Condensation
An aldol condensation is a condensation reaction in organic chemistry in which two carbonyl moieties (of aldehydes or ketones) react to form a β-hydroxyaldehyde or β-hydroxyketone (an aldol reaction), and this is then followed by dehydration to give a conjugated enone. The overall reaction is as follows (where the Rs can be H): Aldol condensations are important in organic synthesis and biochemistry as ways to form carbon–carbon bonds. In its usual form, it involves the nucleophilic addition of a ketone enolate to an aldehyde to form a β-hydroxy ketone, or "aldol" (aldehyde + alcohol), a structural unit found in many naturally occurring molecules and pharmaceuticals. The term ''aldol condensation'' is also commonly used, especially in biochemistry, to refer to just the first (addition) stage of the process—the aldol reaction itself—as catalyzed by aldolases. However, this is formally an addition reaction rather than a condensation reaction because it does not invo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
