Determination of the Nucleophilicities of Silyl and Alkyl Enol Ethers. Biochimica et Biophysica Acta (BBA) - General Subjects. Hydrogenolyse von Trimethylsilylenolethern unter Verwendung eines sauren Rutheniumdiwasserstoff-Komplexes als Katalysator. Mechanistic change in acid-catalyzed hydrolysis of silyl vinyl ethers. Hideaki Ishibashi, Kazuaki Ishihara, Hisashi Yamamoto. Waldemar Adam, Wilhelm J. Baader, Giuseppe Cilento. The Rubottom oxidation is a useful, high-yielding chemical reaction between silyl enol ethers and peroxyacids to give the corresponding α-hydroxy carbonyl product. The effect of a conjugated phenyl group on enol and enolate stability. Cyclisation Reactions Involving Alkyl Enol Ethers. J.B. Sweeney, S. Thobhani, in Comprehensive Organic Functional Group Transformations II, 2005. By virtue of their bonding situation, enol ethers display distinctive reactivity. 2-Indanone and its enol. Reactions of Compounds of the Nonmetallic Elements. 2-Indanone and its enol. The mechanism of the reaction was proposed in its original disclosure by A.G. Brook with further evidence later supplied by George M. Rubottom. , Ullmann's Encyclopedia of Industrial Chemistry, "Iridium-catalyzed Synthesis of Vinyl Ethers from Alcohols and Vinyl Acetate", https://en.wikipedia.org/w/index.php?title=Enol_ether&oldid=982494814, Creative Commons Attribution-ShareAlike License, This page was last edited on 8 October 2020, at 14:15. Find more information on the Altmetric Attention Score and how the score is calculated. ChemInform Abstract: MECHANISTIC CHANGE IN ACID-CATALYZED HYDROLYSIS OF SILYL VINYL ETHERS. Allyl aryl ethers undergo a sequential Claisen rearrangement–cyclization reaction when heated with molybdenum hexacarbonyl in toluene to give 2-substituted dihydrobenzofurans <1997S41> (Equation (75)). Article Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. The reactivity of enol ethers is highly dependent on the presence of substituents alpha to oxygen. Journal of the American Chemical Society 1998, 120 (15) , 3629-3634. Although enol ethers can be considered the ether of the corresponding enolates, they are not prepared by alkylation of enolates. The oxidation of enol ethers and their derivatives is a useful method for the synthesis of α-hydroxy- ketones or their derivatives, which are versatile building blocks for organic synthesis. Note: Jay C. Selover, George D. Vaughn, C. E. Strouse, J. Magnetic Field Effects and Radical Pair Mechanisms in Enzymes: A Reappraisal of the Horseradish Peroxidase System. Your Mendeley pairing has expired. Spiroacetal enol ethers are obtained from the cyclization of 1-methyoxycarbonyl-9-hydroxy-5-oxohept-1-ynes 129 <1996TL5707>. Enol ethers are obtained from α-bromo dioxane and dioxolane acetals 141 by treatment with SmI2 (Equation (39)) <2001TL3729>. Nigel D. A. Walshe, Graham B. T. Goodwin, Graham C. Smith, Frank E. Woodward. Some chemistry of isobutyraldehyde enol. Nobujiro Shimizu, Sho-ichiro Matsuno, Masayuki Tanaka, Yuho Tsuno. You have to login with your ACS ID befor you can login with your Mendeley account. Yoshiaki Nishibayashi, Izuru Takei, Masanobu Hidai.  The general structure is R2C=CR-OR where R = H, alkyl or aryl. On the mechanism of diels-alder reactions of nitroso alkenes:exo/endo selectivity, stereospecificity,E/Z selectivity, and relative reactivity of various olefins. Important enol ethers include the reagent 3,4-dihydropyran and the monomers methyl vinyl ether and ethyl vinyl ether. Chemoselective Ruthenium-Catalyzed Reduction of Acid Chlorides to Aldehydes with Dimethylphenylsilane. A. Gladysz. Dmitry V. Gutsulyak, Georgii I. Nikonov. Regioselective synthesis of -butyldimethylsilyl enol ethers containing an amino group.. Enol ethers bearing α substituents do not polymerize readily. Izuru Takei, Yoshiaki Nishibayashi, Youichi Ishii, Yasushi Mizobe, Sakae Uemura, Masanobu Hidai. The stereochemistry of the product of the reaction can be chosen by judicious choice of conditions (Equation (71)). In lieu of an abstract, this is the article's first page. Configuration-dependent Stereochemistry in 2,4-Dichloro-3-pentanone-Its Enol Trimethylsilyl Ether Interconversion. Florine Cavelier, Sylvie Gomez, Robert Jacquier, Jean Verducci. Nobujiro Shimizu, Shoichiro Matsuno, Masayuki Tanaka, Yuho Tsuno. A common subfamily of enol ethers are vinyl ethers, with the formula ROCH=CH2. Reaction of 54 with 1,2- or 1,3-disubstituted glycerol gives the lipid-type orthoesters in good to moderate yields depending on the degree of substitution of the alcohol <2004AGE1117>. After a Prilezhaev-type oxidation of the silyl enol ether with the peroxyacid to form the … The reaction can be used to prepare flavonoid and vitamin E analogs (Equation (77)). Hans-Ulrich Reißig, Claudia Hippeli, Thomas Arnold. How nucleophilic are silyl enol ethers? The cycloaddition of oxoallyl carbocations (generated from dibromo 2-pentanone with diethylzinc) and furans allows the preparation of bicyclic ketoethers, in moderate yield (Equation (74)) <1996S31>. Some enol ethers are prepared from saturated ethers by elimination reactions. Please note: If you switch to a different device, you may be asked to login again with only your ACS ID. The effect of a conjugated phenyl group on enol and enolate stability. Find more information about Crossref citation counts. Generation of simple enols in aqueous solution from alkali metal enolates. reported that Mn(salen) (43) catalyzed the asymmetric oxidation of silyl enol ethers to give a mixture of α-siloxy and α-hydroxy ketones, albeit with moderate enantioselectivity (Scheme 28).135 Jacobsen et al. If 1,2-disubstituted alkenes are used in the reaction, the regioselectivity of the etherification is altered and benzopyrans are obtained after dehydroiodination. Based on the analysis of the stereochemistry,137 enol ethers have been proposed to approach the oxo-Mn center along the NMn bond axis (trajectory c, vide supra). A Novel Configuration-Controlled Stereoselectivity in Enol Silylation of Ketones. Synthesis and reactivity of metal .alpha.-hydroxyalkyl complexes; generation of (CO)5MCH(C6H5)OH (M = Mn, Re). The synthesis of enol ethers from acetals under basic conditions involves the elimination of an alkoxide ion, which limits this procedure to substrates that can tolerate exposure to strong base. Bicyclic hydropyrans and spiroethers are obtained from palladium-catalyzed intramolecular, 1,4-dialkoxylation of 1-ω-alkoxycyclohexa-1,3-dienes <1998TL1223> (Equation (73)). The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. In comparison with simple alkenes, enol ethers exhibit enhanced susceptibility to attack by electrophiles such as Bronsted acids. Et2O in aqueous methanol to give the N-substituted 2-aminocyclohexanone 53 in 95% yield as a single stereoisomer (Scheme 9; <1999EJO2709>). This transformation thus offers an easy access to the variety of aryl-substituted amines 49 <2005OL4685>. Copyright © 2020 Elsevier B.V. or its licensors or contributors. The oxidation of enol ethers and enol silyl ethers proceeds with enantioselectivity as high as that of the corresponding dihydroxylation of olefins (vide infra) (Scheme 30).139 It is noteworthy that the oxidation of E- and Z-enol ethers gives the same product, and the E/Z ratio of the substrates does not strongly affect the enantioselectivity of the oxidation. These metrics are regularly updated to reflect usage leading up to the last few days. 9 Among several reported secondary oxidants, the … Under HBF4 catalysis reaction undergoes smoothly and provides derivative of myristyl alcohol 55. Since enol ethers and esters are types of olefin, some asymmetric epoxidation and dihydroxylation reactions have been applied to their oxidation. The reaction proceeds by initial regioselective addition of the organolithium reagent to the alkene in compound 140 (likely via a LiO coordinated species) followed by syn-elimination of lithium alkoxide to give (E)-alkenes with high geometric selectivity (Equation (38)). Some enol ethers are prepared from saturated ethers by elimination reactions. This reaction has also been applied to the asymmetric oxidation of cyclic ketene acetals to give an α-hydroxy lactone.140, C.K.-F. Chiu, ... Z.B. Enol ethers have oxonium ion character. Silyl enol ethers can be dihydroxylated with osmium tetroxide to provide α-hydroxy carbonyl compounds after hydrolysis. Find more information about Crossref citation counts. T. Katsuki, in Comprehensive Coordination Chemistry II, 2003. Bulletin of the Chemical Society of Japan. Mechanism of the Rubottom Oxidation The enol ether double bond is epoxidized by the peracid . Octafluorodibenzofuran 130 is prepared by the reaction of perfluorinated dicyclohexyl ethers with benzophenone radical anion <1998JCS(P1)637> (Equation (76)). Similarly, they undergo inverse demand Diels-Alder reactions.. Jens Burfeindt,, Matthias Patz,, Michaela Müller, and. Alex R. Jones,, Nigel S. Scrutton, and. as intermediates in the synthesis of more complex molecules. The acid-catalyzed addition of hydrogen peroxide to vinyl ethers gives the hydroperoxide:, Although enol ethers can be considered the ether of the corresponding enolates, they are not prepared by alkylation of enolates. The homologous compounds do not react as efficiently (Equation (72)). examined the oxidation of enol esters with Mn(salen) (27) and achieved good enantioselectivity.136 Adam et al. Akin to enamines, enol ethers are electron-rich alkenes by virtue of the electron-donation from the heteroatom via pi-bonding. Katsuki et al. Dienyl and trienyl enol ethers can be prepared in a similar manner by 1,4- or 1,6-elimination reactions of the appropriately functionalized acetals <1996CC1295, 1998TL2335>.  Some vinyl ethers also find some use as inhalation anesthetics. Enantioselective Protonation of Silyl Enol Ethers and Ketene Disilyl Acetals with Lewis Acid-Assisted Chiral Brønsted Acids: Reaction Scope and Mechanistic Insights. Brian Capon, Bo Zhang Guo, Fu Chiu Kwok, Arup K. Siddhanta, and Cesar Zucco. DOI: 10.1021/ja974003w. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. James R. Keeffe, A. J. Kresge, Y. Yin. The vinyl ethers are susceptible to polymerization to give polyvinyl ethers. In a similar process, 2-iodomethyldihydrobenzofurans are prepared by the reaction of 2-allyl phenols with tin(IV) chloride and elemental iodine <1997S23> (Scheme 46). Other catalysts examined included trifluoromethanesulfonic acid, methanesulfonic acid, and anhydrous HCl in diethyl ether, but none were as effective as HBF4. Citations are the number of other articles citing this article, calculated by Crossref and updated daily. https://doi.org/10.1016/S0022-328X(03)00470-4, https://doi.org/10.1002/0471264180.os065.01, https://doi.org/10.1002/(SICI)1521-3757(19991018)111:20<3244::AID-ANGE3244>3.0.CO;2-9, https://doi.org/10.1016/S0040-4039(00)79164-7, https://doi.org/10.1016/S0957-4166(00)82229-6, https://doi.org/10.1016/0304-4165(86)90023-1, https://doi.org/10.1016/S0040-4039(01)91296-1, https://doi.org/10.1007/978-1-4615-7410-1_3.
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