This is the first largescale application of the shi epoxidation methodology. When racemic 3isopropylcyclohexene was subjected to dmd oxidation, the trans epoxide, which resulted from attack on the less hindered face of the double bond, was the major product. Request pdf on jun 1, 2019, benjamin list and others published the shi epoxidation find, read and cite all the research you need on researchgate. Guidelines for asymmetric epoxidation prepared by o. Naocl mnsalen catalyst ch 2 cl 2 r 1 r 2 o h h r 1 r 2 r 3 r3co 3 h r 2 o h r 3 r 1 r 1 r 2 oxone h 2 o,ch 3 cn ph 10. Catalytic asymmetric epoxidation of alkenes has been the focus of many research efforts over the past two decades, the best known methods probably being. Largescale synthesis of enantioselective epoxidation catalysts. It is proposed that the shi epoxidation proceeds through a dioxirane intermediate and a spiro transition state and that a socalled planar transition state is a main competing pathway. An efficient catalytic asymmetric epoxidation method.
Organocatalytic asymmetric epoxidation of olefins by chiral ketones. The chirality of the product of a sharpless epoxidation is sometimes predicted with the following mnemonic. Modified heterogeneous silver catalysts are typically employed. Sharpless asymmetric epoxidation mcmaster university. Sharpless epoxidation organic chemistry video clutch prep. In this example, excess tbhp was quenched with triethylphosphite instead of feii sulfate. These are not indefinitely stable, but can be generated in situ by oxidation of a ketone with potassium peroxymonosulfate oxone. Enantioselective epoxidation of terminal olefins by chiral. An efficient asymmetric epoxidation method for trans.
While the practical utility of this protocol is indisputable, the mechanistic underpinnings have been the matter of some debate. H 2o 2 ch 3cn may also be used as stoichiometic oxidant. Catalytic asymmetric epoxidation of alkenes has been the focus of many research efforts over the past two decades, the best known methods probably being those developed by sharpless 1 and jacobsenkatsuki. We also acknowledge previous national science foundation support under grant numbers 1246120, 1525057, and 14739. Journal of the american chemical society 2005, 127 18, 66796685. The largescale preparation of the catalyst 10 is also described.
Download pdf introduction metal cluster catalysts at the subnanoscale often possess unique and unexpected catalytic properties that normally do not exist in the corresponding nanoparticle. Johnsonclaisen rearrangement was employed to obtain the required carbon backbone, whilst intramolecular reductive otonring expansion of a. Epoxidation with in situ prepared manganese based homogeneous catalysts 69 stepwise mechanism route b operates, rotation around the former double bond in 6 can cause isomerization during reaction leading to the obtainment of transepoxides from cisolefins. The peroxy phenylacetic acid generated was then utilised directly for in situ oxidation of alkenes. Epoxidation with in situ prepared manganese based homogeneous. Deepoxidation synonyms, deepoxidation pronunciation, deepoxidation translation, english dictionary definition of deepoxidation. The sharpless epoxidation has been used for the total synthesis of various saccharides, terpenes, leukotrienes, pheromones, and antibiotics. This procedure generates epoxides with high enantiomeric excesses from transdisubstituted alkenes and trisubstituted alkenes. Technology as shown in the attached scheme, enti shi ketone the described catalyst synthesis starts with labsorbic acid vitamin c, a very inexpensive material. This document was downloaded for personal use only. Synthesis of the schweinfurthin hexahydroxanthene core.
Usa home product directory chemical synthesis asymmetric synthesis chiral catalysts, ligands, and reagents epoxidation chemistry products new chemistry products. Volume 49, issue 40, 29 september 2008, pages 57365738. The epoxidation of ethylene involves its reaction of oxygen according to the following stoichiometry. Shi epoxidation wikipedia wikipedia yian shi group. This article is within the scope of wikiproject chemistry, a collaborative effort to improve the coverage of chemistry on wikipedia. Highly enantioselective epoxidation of enol silyl ethers. These are not indefinitely stable, but can be generated in situ by. Pdf efficient soluble polymersupported sharpless alkene. A ringshaped organic compound consisting of an oxygen atom bonded to two other atoms, usually of carbon, that are already bonded to each other. Sharplesskatsuki asymmetric epoxidation sharpless ae. Pdf advances in homogeneous and heterogeneous catalytic. It is an organocatalyst with oxone typically used as the primary oxidant.
Practical synthesis of shis diester fructose derivative for. The asymmetric epoxidation of alkenes using the in situ generated chiral dioxirane formed from the fructosederived ketone precatalyst and oxone potassium peroxymonosulfate is called the shi epoxidation. Download fulltext pdf epoxidation in vivo of hyoscyamine to scopolamine does not involve a dehydration step article pdf available in plant physiology 841. Shi asymmetric epoxidation chiral dioxirane strategy. Carbon nitride supported fe 2 cluster catalysts with. Epoxidation definition and meaning collins english. The epoxidizing species is believed to be a dioxirane, which is a powerful epoxidation reagent. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks. Examples of the sharpless asymmetric epoxidation reaction in industry. Oxidation by secondary amine n,ndioxoradical derived from electron spin resonance, electrospray ionizationmass spectrometry and density functional theory calculation, journal of molecular catalysis a. The catalyst is easily prepared from fructose and displays broad generality.
Other groups have used shis methodology in pursuit of a number of unique structural moieties. Author links open overlay panel lourdusamy emmanuvel arumugam sudalai. N o ch3 h3co et o h h3c ch3 n n ch3 ch3 ch3 etli et2o ch3 et h h3c ch3 n n ch3 ch3 o ch3 o li h n 3c h3c et et oh et et oh o et et o o mg br 1. As such successful chirality recognition of the winding vineshaped compound was in hand by shis epoxidation, the reaction was applied to the kinetic resolution of. The commercial available mcpba is a widely used reagent for this conversion, while magnesium monoperphthalate and peracetic acid are also employed. Catalytic asymmetric epoxidation of allylic alcohols. Epoxidation in vivo of hyoscyamine to scopolamine does not. This new approach should facilitate the preparation of substantial amounts of the materials of interest. Nucleophilic epoxidation is the formation of epoxides from electrondeficient double bonds through the action of nucleophilic oxidants. Stub this article has been rated as stubclass on the projects quality scale. Media in category shi epoxidation the following 12 files are in this category, out of 12 total. The shi epoxidation is a chemical reaction described as the asymmetric epoxidation of alkenes. Ringopening of this epoxide with a vinylcopper complex afforded alcohol 26 instead of the. Article views are the countercompliant sum of full text article downloads since november 2008 both pdf and html across all institutions and individuals.
The shi method is the assymetric epoxidation of alkenes with oxone and a fructosederived catalyst. The reaction proceeds under basic conditions and within a mild temperature range 0. Barry sharpless figured this puzzle out in 1980, receiving a nobel prize in 2001. Epoxidation definition is a conversion of a usually unsaturated compound into an epoxide. A practical synthesis of shis diester 3 for catalytic asymmetric epoxidations has been developed. The potassium salt of the unsaturated acid precursor 7 was prepared by a suzuki coupling from 3fluorobenzyl chloride and the. The journal of organic chemistry 2009, 74 10, 39863989. Jan 26, 2018 as such successful chirality recognition of the winding vineshaped compound was in hand by shis epoxidation, the reaction was applied to the kinetic resolution of racemic 1 as summarized. A diacetate ketonecatalyzed asymmetric epoxidation of olefins. Highly enantioselective epoxidation of cisolefins by chiral. Myers sharpless asymmetric epoxidation reaction chem 115 3. Here, we focused on a simple enzymatic epoxidation of alkenes using lipase and phenylacetic acid. The largescale epoxidation of the alkene 7 with the organocatalyst, epoxone 10, and oxone as the oxidant is described. Nucleophilic epoxidation methods represent a viable alternative to electrophilic methods, many of which do not epoxidize electronpoor double bonds efficiently.
Highly enantioselective and efficient asymmetric epoxidation catalysts. A rectangle is drawn around the double bond in the same plane as the carbons of the double bond the xyplane, with the allylic alcohol in the bottom right corner and the other substituents in their appropriate corners. Download fulltext pdf epoxidation of nhexene and cyclohexene over titaniumcontaining catalysts article pdf available in korean journal of chemical engineering 171. Andrea wong, brian nettles, meixin zhao, dajun chen and yian shi. Isotope effects and the nature of enantioselectivity in the shi epoxidation. Efficiency, cost, and selectivity aspects of the reagents involved for its preparation have been taken care of during its preparation. Hongchang shi and yong li, aminecatalyzed olefin epoxidation mechanism with enantioselectivity. Pdf epoxidation of nhexene and cyclohexene over titanium. Pdf highly efficient asymmetric epoxidation of olefins with a chiral. Mn mediated epoxidation of alkenes the jacobsenkatsuki epoxidation. Deepoxidation definition of deepoxidation by the free. An asymmetric epoxidation using a fructosederived chiral ketone. The epoxidation of an alkene with peracid to give an oxirane.
The shi epoxidation allows the synthesis of epoxides from various alkenes using a fructosederived organocatalyst with oxone as the primary oxidant. How do you select for one enantiomer over another side note. Ready enantioselective epoxidation with dioxiranes several groups have developed chiral ketones as catalysts for asymmetric epoxidation. Pergamon tetrahedron letters 39 1998 78197822 tetrahedron letiers highly enantioselective epoxidation of enol silyl ethers and esters yuanming zhu, yong tu, hongwu yu, yian shi department of chemistry, colorado state university, fort collins, co 80523 emil. Other groups have used shi s methodology in pursuit of a number of unique structural moieties. Epoxidation definition of epoxidation by merriamwebster. The reaction proceeds under basic conditions and within a. In this example, a stoichiometric amount of titanium and dipt was necessary for high conversion. Download fulltext pdf efficient soluble polymersupported sharpless alkene epoxidation catalysts article pdf available in chemical communications february 2002 with 33 reads. Inorganic nanosheets modified with amino acids as ligands jiuzhao wang state key laboratory of chemical resource engineering, beijing university of chemical technology, box 98, beijing, 29 china. Mid this article has been rated as midimportance on. Chirality recognition of winding vineshaped heterobiaryls.
Epoxidation of an asymmetrical alkene is usually a nonstereospecfic process, yielding a racemic mixture of enantiomers. Pdf exploration of an epoxidationringopening strategy for. Shi epoxidation rubottom oxidation synthesis of epoxides. Technology as shown in the attached scheme, entishi ketone the described catalyst synthesis starts with labsorbic acid vitamin c, a very inexpensive material. Pdf exploration of an epoxidationringopening strategy. Diastereoselective epoxidation may be achieved through the use of alkene starting materials with diastereotopic faces. Jun 15, 2018 download pdf introduction metal cluster catalysts at the subnanoscale often possess unique and unexpected catalytic properties that normally do not exist in the corresponding nanoparticle. Chiral ketonecatalyzed asymmetric epoxidation of olefins. Highly enantioselective epoxidation of cisolefins by. The libretexts libraries are powered by mindtouch and are supported by the department of education open textbook pilot project, the uc davis office of the provost, the uc davis library, the california state university affordable learning solutions program, and merlot. Practical synthesis of shis diester fructose derivative.
The shi epoxidation is a chemical reaction described as an asymmetric epoxidation of olefins with oxone potassium peroxymonosulfate and a fructosederived catalyst 1. The direct reaction of oxygen with alkenes is useful only for this epoxide. The immobilised candida antarctica lipase b, novozym 435 was used to catalyse the formation of peroxy acid instantly from hydrogen peroxide h 2 o 2 and phenylacetic acid. This is the case with manganesesalen catalyzed epoxidation of cinnamate esters with. Largescale synthesis of enantioselective epoxidation. Here, we report a new synthesis of the hexahydroxanthene 7 that exploits shi epoxidation to obtain nonracemic intermediates in both improved yield and high ee. In catalytic asymmetric synthesis, 2nd ed ojima, i.
Myers sharpless asymmetric epoxidation reaction chem 115. For example, mcdonald and coworkers recently reported a robust and selective synthesis of 2amino3,5diols that employs the shi epoxidation in a key step scheme 5. Substrate scope of ketone 1 o o o o o o 1 ph ph o 85% yield 98% ee c6h c6h 89%. The sulfate as a good leaving group facilitates the ring closure to the dioxiranes. The catalyst has been prepared in multigram quantities from dfructose in four steps with a 66% overall yield. Pdf catalytic asymmetric epoxidation is a useful technique for the synthesis of chiral compounds in both academia and industry.
Chemoenzymatic epoxidation of alkenes and reusability. Pages in category epoxidation reactions the following 7 pages are in this category, out of 7 total. Highly enantioselective epoxidation of enol silyl ethers and. This paper describes an enantioselective epoxidation of terminal olefins using chiral ketone 3 as catalyst and oxone as oxidant. This reaction is thought to proceed via a dioxirane intermediate, generated from the catalyst ketone by oxone potassium peroxymonosulfate. Pdf epoxidation in vivo of hyoscyamine to scopolamine does. The addition of the sulfate group by the oxone facilitates the formation of the.
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