- Simple metal oxides as efficient heterogeneous catalysts for epoxidation of alkenes by molecular oxygen
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Magnetite iron oxide (Fe3O4) has been found to be an efficient heterogeneous catalyst for the epoxidation of alkenes by molecular oxygen in the absence of a sacrificial reductant among various transition metal oxides. The reaction probably proceeds via a radical mechanism.
- Liang, Jun,Tang, Qinghu,Meng, Guanyu,Wu, Hongli,Zhang, Qinghong,Wang, Ye
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Read Online
- Facile synthesis of libraries of functionalized cyclopropanes and oxiranes using ionic liquids – A new approach to the classical Corey-Chaykovsky reaction
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The potential of [PAIM][NTf2]/BMIM-ILs as a base/solvent in the Corey-Chaykovsky reaction is demonstrated by the facile synthesis of libraries of functionalized cyclopropanes from enones and oxiranes from aldehydes and ketones, at room temperature in respectable isolated yields. To demonstrate their application, the synthesized epoxides were employed as substrates for the synthesis of a library of 2,3-disubstituted quinolines, using [BMIM(SO3H)][OTf]/[BMIM][PF6] as a catalyst/solvent. The potential for recycling/reuse of the IL solvents was also explored.
- Malunavar, Shruti S.,Sutar, Suraj M.,Prabhala, Pavankumar,Savanur, Hemantkumar M.,Kalkhambkar, Rajesh G.,Aridoss, Gopalakrishnan,Laali, Kenneth K.
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supporting information
(2021/09/13)
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- A new and efficient methodology for olefin epoxidation catalyzed by supported cobalt nanoparticles
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A new heterogeneous catalytic system consisting of cobalt nanoparticles (CoNPs) supported on MgO and tert-butyl hydroperoxide (TBHP) as oxidant is presented. This CoNPs@MgO/t-BuOOH catalytic combination allowed the epoxidation of a variety of olefins with good to excellent yield and high selectivity. The catalyst preparation is simple and straightforward from commercially available starting materials and it could be recovered and reused maintaining its unaltered high activity.
- Rossi-Fernández, Lucía,Dorn, Viviana,Radivoy, Gabriel
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supporting information
p. 519 - 526
(2021/03/31)
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- Continuous Flow Synthesis of Terminal Epoxides from Ketones Using in Situ Generated Bromomethyl Lithium
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A scalable procedure for the direct preparation of epoxides from ketones has been developed. The method is based on the carefully controlled generation of (bromomethyl)lithium (LiCH2Br) from inexpensive CH2Br2 and MeLi in a continuous flow reactor. The reaction has shown excellent selectivity for a variety of substrates, including α-chloroketones, which typically fail under classic Corey-Chaykovsky conditions. This advantage has been used to develop a novel route toward the drug fluconazole.
- Von Keutz, Timo,Cantillo, David,Kappe, C. Oliver
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supporting information
p. 10094 - 10098
(2019/12/24)
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- Retro-Corey-Chaykovsky Epoxidation: Converting Geminal Disubstituted Epoxides to Ketones
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Corey-Chaykovsky epoxidation has been widely applied in the conversion of aldehydes and ketones to epoxides with sulfonium and sulfoxonium ylides. The reverse transformation is realized for conversion of geminal disubstituted epoxides to ketones in the presence of DABCO in refluxing mesitylene. The method is a weak basic transformation from epoxides to ketones with loss of a methylene group and can be applied as an alternative strategy of the acid-catalyzed Meinwald rearrangement or oxidation for conversion of epoxides to carbonyl compounds.
- Li, Siqi,Li, Pingfan,Xu, Jiaxi
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- Oxidative Cleavage of Alkene C=C Bonds Using a Manganese Catalyzed Oxidation with H2O2 Combined with Periodate Oxidation
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A one-pot multi-step method for the oxidative cleavage of alkenes to aldehydes/ketones under ambient conditions is described as an alternative to ozonolysis. The first step is a highly efficient manganese catalyzed epoxidation/cis-dihydroxylation of alkenes. This step is followed by an Fe(III) assisted ring opening of the epoxide (where necessary) to a 1,2-diol. Carbon–carbon bond cleavage is achieved by treatment of the diol with sodium periodate. The conditions used in each step are not only compatible with the subsequent step(s), but also provide for increased conversion compared to the equivalent reactions carried out on the isolated intermediate compounds. The described procedure allows for carbon–carbon bond cleavage in the presence of other alkenes, oxidation sensitive moieties and other functional groups; the mild conditions (r.t.) used in all three steps make this a viable general alternative to ozonolysis and especially for use under flow or continuous batch conditions.
- Mecozzi, Francesco,Dong, Jia Jia,Angelone, Davide,Browne, Wesley R.,Eisink, Niek N. H. M.
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supporting information
p. 7151 - 7158
(2019/11/16)
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- QUINUCLIDINE DERIVATIVE
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Provided is a novel therapeutic agent for chronic obstructive pulmonary disease. Provided are a quinuclidine derivative and a medicament comprising the quinuclidine derivative. wherein R1 represents a hydrogen atom, a halogen atom, a lower alkyl group, a haloalkyl group, a lower alkoxy group, or a haloalkoxy group; Y represents —C(C═O)—O—, —CH2—, or —CH2O—; m represents an integer of 1 to 5; Z represents an oxygen atom or a sulfur atom; l represents a number of 0 or 1; n represents an integer of 0 to 4; X? represents an anion; and a substituent of a quinuclidine ring represents a 1,3-bond, or 1,4-bond, provided that when m is 3, l is 1, and n is 0, R1 represents a halogen atom, a lower alkyl group, a haloalkyl group, a lower alkoxy group, or a haloalkoxy group.
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Paragraph 0234; 0235; 0236; 0237; 0238
(2018/03/10)
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- Substituent and Lewis Acid Promoted Dual Behavior of Epoxides towards [3+2]-Annulation Reactions with Donor-Acceptor Cyclopropanes: Synthesis of Substituted Cyclopentane and Tetrahydrofuran
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Substituent and Lewis acid promoted generation of functionalized enolates from epoxides is developed. Divergent attack of the enolate on donor-acceptor cyclopropanes, i.e. C-attack or O-attack depending upon substituents present in both reacting partners, produced different products. C-attack gave functionalized cyclopentane derivatives, whereas O-attack furnished tetrahydrofuran derivatives through [3+2]-annulation reactions. Moreover, to increase the utility of our method, synthesized diastereomeric cyclopentane derivatives were converted into synthetically useful cyclopentene and cyclopentanone analogs.
- Pandey, Ashok Kumar,Varshnaya, Rohit Kumar,Banerjee, Prabal
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p. 1647 - 1656
(2017/04/06)
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- Exploiting a beast in carbenoid chemistry: Development of a straightforward direct nucleophilic fluoromethylation strategy
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The first direct and straightforward nucleophilic fluoromethylation of organic compounds is reported. The tactic employs a fleeting lithium fluorocarbenoid (LiCH2F) generated from commercially available fluoroiodomethane. Precise reaction conditions were developed for the generation and synthetic exploitation of such a labile species. The versatility of the strategy is showcased in ca. 50 examples involving a plethora of electrophiles. Highly valuable chemicals such as fluoroalcohols, fluoroamines, and fluoromethylated oxygenated heterocycles could be prepared in very good yields through a single synthetic operation. The scalability of the reaction and its application to complex molecular architectures (e.g., steroids) are documented.
- Parisi, Giovanna,Colella, Marco,Monticelli, Serena,Romanazzi, Giuseppe,Holzer, Wolfgang,Langer, Thierry,Degennaro, Leonardo,Pace, Vittorio,Luisi, Renzo
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supporting information
p. 13648 - 13651
(2017/11/06)
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- Regioselective hydrosilylation of epoxides catalysed by nickel(II) hydrido complexes
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Bench-stable nickel fluoride complexes bearing NNN pincer ligands have been employed as precursors for the regioselective hydrosilylation of epoxides at room temperature. A nickel hydride assisted epoxide opening is followed by the cleavage of the newly formed nickel oxygen bond by σ-bond metathesis with a silane.
- Wenz, Jan,Wadepohl, Hubert,Gade, Lutz H.
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supporting information
p. 4308 - 4311
(2017/04/21)
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- Rhenium complex-catalyzed Meinwald rearrangement reactions of oxiranes
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The Meinwald rearrangement reaction of oxiranes to the corresponding carbonyl compounds is efficiently catalyzed by the ReBr(CO)5 complex.
- Umeda, Rui,Muraki, Masahito,Nakamura, Yuudai,Tanaka, Tomoyuki,Kamiguchi, Kyohei,Nishiyama, Yutaka
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supporting information
p. 2393 - 2395
(2017/05/29)
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- Indium(III) Chloride Promoted Highly Efficient Tandem Rearrangement-α-Addition Strategy towards the Synthesis of α-Hydroxyamides
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A new tandem process is reported that provides access to α-hydroxyamides from epoxides for the first time. Herein, we explore InCl3-mediated tandem rearrangement of epoxides to aldehydes and α-addition of TosMIC to in situ derived aldehydes. An unprecedented C-C bond-forming reaction is disclosed that features mild conditions, high yields, and shorter reaction times.
- Lingaswamy, Kadari,Mohan, Dumpala,Krishna, Palakodety Radha,Prapurna, Y. Lakshmi
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supporting information
p. 1693 - 1698
(2016/07/06)
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- Traceless directing group mediated branched selective alkenylation of unbiased arenes
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Owing to the synthetic importance of branched olefinated products, we report palladium catalyzed formation of branched olefins facilitated by a C-H activation based protocol. This involves selective insertion of olefins and subsequent decarboxylation using a completely unbiased benzene ring as the starting precursor. The significance of the protocol has been further highlighted by exhibition of functionality tolerance along with a late-stage modification of the branched olefinated products leading to the formation of other functionalized molecules.
- Agasti, Soumitra,Dey, Aniruddha,Maiti, Debabrata
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p. 12191 - 12194
(2016/10/21)
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- Cobalt(II) acetylacetonate complex immobilized on aminosilane-modified SBA-15 as an efficient catalyst for epoxidation of trans-stilbene with molecular oxygen
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From environmental and economic points of view, it is highly desirable to develop a clean and efficient catalytic process to produce epoxides. An attractive approach is to use a solid, recyclable catalyst and molecular oxygen as the oxidant without any sacrificial reductant or other additives. Nonetheless, the catalysts reported up to now still cannot balance catalytic activity with epoxide selectivity. It is of great importance to explore novel catalysts with both high activity and selectivity for the epoxidation of olefins. In this work, cobalt(II) acetylacetonate (Co(acac)2) was covalently bonded to the silica surface of SBA-15 molecular sieve by multi-step grafting using 3-aminopropytrimethoxysilane (APTS) as coupling agent. Characterizations with nitrogen physisorption, X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis suggested that the metal complex was successfully immobilized on the aminosilane-modified SBA-15 surface and the channel structure remained intact. The synthesized Co(acac)2APTS@SBA-15 catalyst was used in the epoxidation of trans-stilbene (TS) with molecular oxygen. Compared to the sample prepared by the impregnation method as well as Co(acac)2 solutions under the same reaction conditions, the Co(acac)2 immobilized catalyst exhibited remarkably higher TS conversion and trans-stilbene oxide (TSO) selectivity. An increase in TS conversion with Co content was observed when the Co loading was lower than 0.70% and the 0.70Co(acac)2APTS@SBA-15 sample exhibited the best catalytic performance. Up to 50.1% of TS conversion could be achieved within 6 h, affording TSO selectivity as high as 96.7%. The superior catalytic performance of this particular catalyst is attributed to the high activity of the immobilized Co(acac)2 species on SBA-15.
- Tang, Qinghu,Wang, Yanyan,Zhang, Jian,Qiao, Ran,Xie, Xiaopei,Wang, Yi,Yang, Yanhui
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p. 435 - 440
(2016/05/19)
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- Water-compatible gold and silver nanoparticles as catalysts for the oxidation of alkenes
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Water-compatible Ag/Au nanoparticles (NP) catalyze the liquid-phase oxidation of 1,1-diphenylethylene to afford benzophenone, the product of oxidative cleavage, and 1,1-diphenylepoxide. The metal nanoparticles are surface functionalized with tannic acid and/or citrate and have diameters of 10–12 nm. By proper selection of the reaction conditions, percent conversions/distributions of 85–100% of 1,1-diphenylethylene can be achieved at 90 °C using water as a solvent and TBHP (tert-butylhydroperoxide) as the co-oxidant. In addition, these nanoparticles have been further supported on functionalized silica to improve their stability and recyclability in this oxidation process. Conversions of up to 100% to benzophenone could be obtained with 1.5 mol% Au or Ag nanoparticles (10 nm) supported on functionalized silica. The supported NP could be recycled and re-used without significant catalytic activity loss for three runs.
- Fisher, Eugenia,Kenisgberg, Lea,Carreira, Monica,Fernández-Gallardo, Jacob,Baldwin, Richard,Contel, María
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supporting information
p. 82 - 87
(2016/12/06)
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- Facile access to α-acyloxyamides via epoxide rearrangement/three-component domino reaction catalyzed by indium(III) chloride
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A simple and efficient Passerini reaction of epoxides involving highly regioselective rearrangement of epoxide to aldehyde/three-component Passerini reaction catalyzed by indium(III) chloride is described. In the present protocol, epoxides served as wonderful substrates to furnish a library of α-acyloxyamides under mild reaction conditions in shorter reaction times and in good yields.
- Lingaswamy, Kadari,Krishna, Palakodety Radha,Prapurna, Y. Lakshmi
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supporting information
p. 1275 - 1282
(2016/08/16)
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- Regioselective and Stereospecific Copper-Catalyzed Deoxygenation of Epoxides to Alkenes
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Two copper salts (Cu(CF3CO2)2 and IMesCuCl) were identified as earth-abundant, inexpensive, but effective metal catalysts together with diazo malonate for chemo-/regioselective and stereospecific deoxygenation of various epoxides with tolerance of common functional groups (alkene, ketone, ester, p-methoxybenzyl, benzyl, tert-butyldimethylsilyl, and triisopropylsilyl). In particular, the unprecedented regioselectivity allowed for the first time monodeoxygenation of diepoxides to alkenyl epoxides. Density functional theory mechanistic studies showed that the deoxygenation occurred by collapsing the free ylide, unfavoring the possible intuitive pathway via cycloreversion of possible oxetane.
- Yu, Jingxun,Zhou, Yu,Lin, Zhenyang,Tong, Rongbiao
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supporting information
p. 4734 - 4737
(2016/09/28)
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- A Mn (III)-Salen catalyst and its preparation method and application
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The invention discloses a Mn(III)-Salen catalyst as well as a preparation method and application thereof. The method comprises the following steps: performing reaction on 5-bromo-3-tert-butyl salicylaldehyde and pyridine-4-boric acid as raw materials to generate pyridine salicylaldehyde derivatives; reacting the pyridine salicylaldehyde derivatives with ethylene diamine to synthesize a Salen ligand with a pyridine functional group; finally coordinating divalent manganese salt with the Salen ligand, oxidizing, evaporating an obtained reaction solution to dryness, washing by water and filtering to obtain the Mn(III)-Salen catalyst. According to the method, a reaction system is simple, a reagent is easily available and low in cost, a reaction product post-treatment process is simple, the product purity is high, and the obtained Mn(III)-Salen catalyst is stable to water and air and capable of catalyzing styrene, 4-tert-butyl styrene, indene, alpha-methyl styrene and the like in a manner of relatively high activity and selectivity to synthesize olefin epoxides.
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Paragraph 0083; 0084
(2017/02/02)
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- Efficient Epoxidation of Styrene Derivatives by a Nonheme Iron(IV)-Oxo Complex via Proton-Coupled Electron Transfer with Triflic Acid
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Styrene derivatives are not oxidized by [(N4Py)FeIV(O)]2+ (N4Py = N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine) in acetonitrile at 298 K, whereas epoxidation of styrene derivatives by the iron(IV)-oxo complex occurs efficiently in the presence of triflic acid (HOTf) via proton-coupled electron transfer (PCET) from styrene derivatives to the diprotonated species of [(N4Py)FeIV(O)]2+ with HOTf. Logarithms of the first-order rate constants of HOTf-promoted expoxidation of styrene derivatives with [(N4Py)FeIV(O)]2+ and PCET from electron donors to [(N4Py)FeIV(O)]2+ in the precursor complexes exhibit a remarkably unified correlation with the driving force of PCET in light of the Marcus theory of electron transfer when the differences in the formation constants of precursor complexes are taken into account. The same PCET driving force dependence is obtained for the first-order rate constants of HOTf-promoted oxygen atom transfer from thioanisols to [(N4Py)FeIV(O)]2+ and HOTf-promoted hydrogen atom transfer from toluene derivatives to [(N4Py)FeIV(O)]2+ in the precursor complexes. Thus, HOTf-promoted epoxidation of styrene derivatives by [(N4Py)FeIV(O)]2+ proceeds via the rate-determining electron transfer from styrene derivatives to the diprotonated species of [(N4Py)FeIV(O)]2+, as shown in the reactions of HOTf-promoted oxygen atom transfer from thioanisols to [(N4Py)FeIV(O)]2+ and HOTf-promoted hydrogen atom transfer from toluene derivatives to [(N4Py)FeIV(O)]2+.
- Park, Jiyun,Lee, Yong-Min,Ohkubo, Kei,Nam, Wonwoo,Fukuzumi, Shunichi
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supporting information
p. 5806 - 5812
(2015/06/25)
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- Synthesis of 4-arylpiperidin-4-ol derivatives of loperamide as agents with potent antiproliferative effects against HCT-116 and HL-60 cells
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The structure of 4-arylpiperidin-4-ol, a constituent of the antidiarrheal loperamide, is key to μ opioid receptor activation. Some opioid derivatives were recently reported to induce tumor cell death, but the chemical structures responsible for their antitumor activity remain unclear. We synthesized loperamide analogs and tested their antiproliferative activity against HCT-116 colon tumor cells and HL-60 leukemia cells. The N-substituents on 4-arylpiperidin-4-ol units were found to play an important role in their antiproliferative activity, and the N-diphenylpropanol analogs exhibited the most potent antiproliferative activity. Furthermore, the N-diphenylpropanol analog activated caspase-3, as was found previously for opioids that exhibited antitumor effects.
- Hatae, Noriyuki,Nagayama, Tomoyuki,Esaki, Hiroyoshi,Kujime, Eiko,Minami, Masabumi,Ishikura, Minoru,Choshi, Tominari,Hibino, Satoshi,Okada, Chiaki,Toyota, Eiko,Nagasawa, Hideko,Iwamura, Tatsunori
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p. 663 - 673
(2016/11/13)
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- A lithiomethyl trimethylammonium reagent as a methylene donor
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Straightforward deprotonation of soluble tetramethylammonium salts with alkyllithium reagents gives lithiomethyl trimethylammonium reagents. Coordination of the Li cation is crucial to the stability of these 'N-C ylides'. These reagents were used to prepare epoxides, aziridines and allylic alcohols. This journal is the Partner Organisations 2014.
- Den Hartog, Tim,Sarria Toro, Juan M.,Couzijn, Erik P. A.,Chen, Peter
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supporting information
p. 10604 - 10607
(2014/11/08)
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- Isomerization of terminal epoxides by a [Pd-H] catalyst: A combined experimental and theoretical mechanistic study
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An unusual palladium hydride complex has been shown to be a competent catalyst in the isomerization of a variety of terminal and internal epoxides. The reaction displayed broad scope and synthetic utility. Experimental and theoretical evidence are provided for an unprecedented hydride mechanism characterized by two distinct enantio-determining steps. These results hold promise for the development of an enantioselective variant of the reaction.
- Vyas, Devendra J.,Larionov, Evgeny,Besnard, Celine,Guenee, Laure,Mazet, Clement
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supporting information
p. 6177 - 6183
(2013/06/04)
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- Concerning the deprotonation of the trimethylsulfonium ion by the dimethylsulfinyl anion
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As shown by deuterium labelling experiments, the deprotonation of the trimethylsulfonium ion (1) by the dimsyl anion (8) is accompanied by extensive hydrogen exchange. This cannot be explained by an acid-base equilibrium between the trimethylsulfonium ion (1) and the dimsyl anion (8) on one side and dimethylsulfonium methylide (2) and DMSO on the other side, because for thermodynamic reasons this process is irreversible due to the limited life-time of 2. Therefore, the isotopic exchange that accompanies the deprotonation is an indicator of a more complex deprotonation process. It is suggested that in a kinetically controlled reaction, a proton of 1 is transferred to the O-atom of 8 rather than to the carbanionic centre. This means that instead of DMSO, its tautomer, hydroxy-methylsulfonium methylide (10), is obtained in the deprotonation process. Similarly, in the acid-base interaction between DMSO and its conjugate base 8, the formation of the DMSO tautomer 10 is kinetically favoured. The intermediate 10 produced in this way transfers a DMSO-derived proton to 1 when it intervenes in the back reaction 10 + 2 → 8 + 1. An alternative mechanism based on methyl group exchange between 1 and 8 could be excluded by a 13C-labelling experiment. The hydrogen exchange according to the suggested scenario is taking place in competition with the reaction of dimethylsulfonium methylide (2) with electrophilic substrates. This explains the different degrees of isotopic exchange when compounds of different electrophilicities are used to scavenge 2 from the deprotonation-hydrogen distribution equilibria.
- Haiss, Peter,Zeller, Klaus-Peter
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experimental part
p. 7748 - 7754
(2011/12/03)
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- Practical corey-chaykovsky epoxidation: Scope and limitation
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Corey-Chaykovsky epoxidation is one of the versatile methods for synthesis of structurally diverse oxiranes. The extension of simplified Corey-Chaykovsky epoxidation has been investigated. Ketones and aromatic aldehydes were epoxidized in satisfactory to excellent yields with trimethylsulfonium iodide as an ylide precursor and crushed potassium hydroxide as a base in tertiary butanol.The scope and limitation of the simplified procedure were examined. The results revealed that the procedure is applicable to the epoxidation of ketones and aromatic aldehydes.
- Yu, Hao,Deng, Xiaobing,Cao, Shengli,Xu, Jiaxi
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experimental part
p. 509 - 514
(2012/04/11)
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- Bis(pyridylimino)isoindolato-iridium complexes as epoxidation catalysts for alkenes
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The reaction of the sodium salts of ligands 1a,b (1a = 1,3-bis(2-(5-(3,5- xylyl)pyridyl)imino)-5,6-dimethylisoindole, 1b = 1,3-bis(2-(4-tert-butylpyridyl) imino)-5,6-dimethylisoindole) with [Ir(μ-Cl)(COD)]2 (COD = cyclooctadiene) and [Ir(μ-Cl)(C2H4)2] 2 afforded the corresponding isoindolato complexes [{BPI(1a,b)}IrI(COD)] (2a,b) and [{BPI(1a,b)}IrI(C 2H4)2] (3a,b), respectively. The catalytic activity of the complexes 2a,b was tested in the epoxidation of a wide range of non-electron-rich olefins, using PPO (PPO = 3-phenyl-2-(phenylsulfonyl)-1,2- oxaziridine) as oxidizing agent, giving the corresponding epoxides in moderate to high yields.
- Camerano, Jose A.,Saemann, Christoph,Wadepohl, Hubert,Gade, Lutz H.
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scheme or table
p. 379 - 382
(2011/03/21)
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- Epoxidation of alkenes and oxidation of alcohols with hydrogen peroxide catalyzed by a manganese(v) nitrido complex
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The manganese(v) nitrido complex (PPh4)2[Mn(N)(CN) 4] is an active catalyst for alkene epoxidation and alcohol oxidation using H2O2 as an oxidant. The catalytic oxidation is greatly enhanced by the addition of just one equivalent of acetic acid. The oxidation of ethene by this system has been studied computationally by the DFT method.
- Kwong, Hoi-Ki,Lo, Po-Kam,Lau, Kai-Chung,Lau, Tai-Chu
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supporting information; experimental part
p. 4273 - 4275
(2011/06/21)
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- Formation of epoxides from pentacoordinated organoarsenic compounds with a β-hydroxyethyl group
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A series of pentacoordinated organoarsenic compounds (arsoranes) bearing a β-hydroxyethyl group (4a, 6a and 6b) was synthesized. The crystal structures were determined by single crystal X-ray analysis. Treatment of these arsoranes with KH almost quantitatively gave the corresponding epoxide. The reaction of 4a having an unsubstituted β-hydroxyethyl group with KH was monitored by 1H and 19F NMR in CD3CN, suggesting that a hexacoordinate arsenic anion was formed as the intermediate. However, a further stereochemical study of the epoxide formation suggested that the reaction proceeded in the SN2 manner and not in the ligand coupling reaction (LCR) of the intermediate hexacoordinate arsenic anion.
- Jiang, Xin-Dong,Matsukawa, Shiro,Fukuzaki, Yuta,Yamamoto, Yohsuke
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p. 1623 - 1629
(2010/10/04)
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- Copper(II) tetrafluroborate-promoted Meinwald rearrangement reactions of epoxides
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Epoxides undergo a highly efficient Meinwald rearrangement in the presence of catalytic quantities of copper(II) tetrafluoroborate to give carbonyl compounds in high yields and with excellent selectivity. The low toxicity and ease of handling of this reagent make it an attractive alternative to the more corrosive or costly Lewis acids frequently employed.
- Robinson, Mathew W.C.,Pillinger, Kathryn S.,Mabbett, Ian,Timms, David A.,Graham, Andrew E.
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supporting information; experimental part
p. 8377 - 8382
(2010/11/19)
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- A chiral iron-sexipyridine complex as a catalyst for alkene epoxidation with hydrogen peroxide
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A chiral iron-sexipyridine complex-hydrogen peroxide mixture is a highly efficient catalytic system for styrene epoxidation with excellent reactivity (3 min, 95% yield) and chemoselectivity (98%). The Royal Society of Chemistry.
- Yeung, Ho-Lun,Sham, Kiu-Chor,Tsang, Chui-Shan,Lau, Tai-Chu,Kwong, Hoi-Lun
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scheme or table
p. 3801 - 3803
(2009/02/08)
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- AZABICYCLIC MUSCARINIC RECEPTOR ANTAGONISTS
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The present invention generally relates to muscarinic receptor antagonists, which are useful for treating various diseases of the respiratory, urinary and gastrointestinal systems mediated through muscarinic receptors. The invention also relates to processes for preparing compounds described herein, pharmaceutical compositions containing the disclosed compounds, and the methods for treating diseases mediated through muscarinic receptors.
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Page/Page column 60
(2010/11/08)
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- Fluorous biphasic catalytic oxidation of alkenes and aldehydes with air and 2-methylpropanal in the presence of (β-perfluoroalkylated tetraphenylporphyrin)cobalt complexes
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A simple and facile fluorous biphasic catalytic oxidation of alkenes and aldehydes with 1 atm of air and 2-methylpropanal in the presence of the (β-perfluoroalkylated tetraphenylporphyrin)cobalt complexes [Co{TPP(C 8F17)4}] (Co2) has been demonstrated for the first time. This kind of β-perfluoroalkylated tetraphenylporphyrin may be used in other catalytic applications because of its ready availability and unique properties. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Liu, Chao,Shen, Dong-Mei,Chen, Qing-Yun
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p. 2703 - 2706
(2007/10/03)
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- Heteroatom transfer to alkenes by N-protected-oxaziridines: New reaction pathways and products
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N-Alkoxycarbonyl- and N-carboxamido-oxaziridines are shown to react with aromatic alkenes to give epoxide, aziridine or hydro-oxidation products, in ratios depending on the oxaziridine structure. Chiral oxaziridines can effect epoxidation and hydro-oxidation with promising levels of asymmetric induction.
- Armstrong, Alan,Edmonds, Ian D.,Swarbrick, Martin E.
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p. 2207 - 2210
(2007/10/03)
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- Polymer-supported thioanisole: A versatile platform for organic synthesis reagents
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A new cross-linked polystyrene-supported thioanisole reagent is reported. This reagent incorporates the flexible JandaJel cross-linker and can be treated with methyl trifluoromethanesulfonate to form the corresponding sulfonium salt. This salt can in turn be deprotonated to form a polymer-supported sulfur ylide that is able to react with aldehydes and ketones to form epoxides. The thioanisole reagent can also be oxidized to form an insoluble sulfoxide reagent that is useful in Swern oxidation reactions. In these reactions, the polymer-supported thioanisole-based reagents can be recovered, regenerated and reused.
- Choi, Matthew Kwok Wai,Toy, Patrick H.
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p. 2875 - 2879
(2007/10/03)
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- "Instant methylide" modification of the Corey-Chaykovsky epoxide synthesis
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We report that Me3S(O)+I- (1) and Me3S+I- (2) form stable, dry mixtures with KOt-Bu and NaH, respectively, which remain stable upon prolonged storage (> 1 year). The corresponding methylides (Me2SO=CH2 and Me2S=CH2) are generated upon addition of DMSO or DMSO/THF solutions of carbonyl compounds, cleanly affording epoxides via the Corey-Chaykovsky reaction in good yields and short reaction times (as short as 20 min when 1-2 mmol of various ketones and aldehydes were treated with a mixture of 1 and KOt-Bu at 50-60°C).
- Ciaccio, James A.,Drahus, Antoinette L.,Meis, Regina M.,Tingle, Carice T.,Smrtka, Michael,Geneste, Richard
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p. 2135 - 2143
(2007/10/03)
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- Zeolite-Promoted Oxidations of 1,1-Diarylethylenes
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(Equation Presented) The intrazeolite photooxygenations of four diarylethylenes have been examined. Several intermediates, including an epoxide, have been identified by comparison to independently synthesized samples. Aldehyde intermediates were shown to undergo intrazeolite Norrish type I cleavages in competition with a novel new photooxygenation/autoxidation reaction.
- Clennan, Edward L.,Pan, Gui-Ian
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p. 4979 - 4982
(2007/10/03)
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- 1,1-Diphenyl-2-methylsulfinyl ethanol: A model compound to study the reactivity towards CNBr of a photoadduct of methionine on CγH2
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The photoadduct formed by photolysis of the [Bapa0, (pBzl)Phe5, Met(O2)11]SP/NK-1 complex localised within the T173MP175 domain of the NK-1 receptor cannot be cleaved by CNBr on the C-side of methionine; an unusual rearrangement of the intermediate sulfonium instead occurred. The reactivity of 1,1-diphenyl-2-methylsulfinyl ethanol 10 towards CNBr treatment and the stability of the 1,1-diphenyl oxirane 14 were analysed by NMR and mass spectrometry. 1,1-Diphenyl ethylene 13 can be formed from epoxide 14 even in slightly acidic conditions and during positive DCI/NH3 mass spectrometry analysis. Altogether, these results suggest that if a covalent linkage between the [Bapa0, (pBzl)Phe5, Met(O2)11] and the NK-1 receptor occurred on the CγH2 of methionine-174, CNBr treatment will lead to an epoxide/ketone and an ethylenic compound.
- Sachon, Emmanuelle,Milcent, Thierry,Sagan, Sandrine,Convert, Odile,Chassaing, Gérard,Lavielle, Solange
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p. 7485 - 7489
(2007/10/03)
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- A comparative product investigation between Grignard reactions of benzophenone and coupling reactions of electrogenerated benzophenone radical anions and alkyl radicals in THF
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The 1,6-to 1,2-addition product ratios of the Grignard reactions of benzophenone with t-, s- and n-C4H9MgCl have been compared with the corresponding ratios obtained by the electrolysis of benzophenone in presence of t-, s- and n-C4H9S+(CH3)2, ClO4-in THF. The Grignard reaction ratios 0.81, 0.50 and 0.19, respectively, were obtained whereas the corresponding electrolysis ratios were 2.26, 1.23 and 1.61. From this comparison of product ratios it is concluded that none of the Grignard reactions of benzophenone proceeds through a complete free coupling process of benzophenone radical anions and butyl radicals. The ET character of the Grignard reactions of benzophenone with t-, s- and n-C4H9MgCl was estimated to be 65, 61 and 26%, respectively.
- Lund, Torben,Ohlrich, Ditte,Borling, Pernille
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p. 932 - 937
(2007/10/03)
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- Reactivity and selectivity in the oxidation of styrene derivatives. V. studies on the oxidation of α-substituted styrenes
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The liquid phase oxidation of α-phenyl-1a, α-trimethylsilyloxy 1b, α-cyclopropyl-1c, α-trifluoromethyl-1d styrene, and styrene 1e with oxygen in chlorobenzene and cumene solution in the temperature range 55-125°C was investigated. The product yields were determined gaschromatographically. The epoxide selectivity increases up to 90°C with increasing temperature. The epoxides of 1a and 1c rearrange at higher temperatures, therefore their yield decreases. The relative chain propagation constants (kpC=C) were determined by competitive oxidations of cumene. WILEY-VCH Verlag GmbH, 1999.
- Suprun
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- Synthesis and complexation of nickel(II) and copper(II) by pendant-arm alcohol derivatives of [9]aneNS2 (7-aza-1,4-dithiacyclononane)
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A simplified procedure for the preparation of [9]aneNS2 (7-aza-1,4-dithiacyclononane) is described. The structure of the complex [Cu([9]aneNS2)2]2+ confirms that the CU(II) centre is in a distorted octahedral environment, Cu-S(1) 2.5469(14), Cu-S(4) 2.5386(13), Cu-N(7) 2.016(4) A. Reaction of [9]aneNS2 with isobutylene oxide or 2,2-diphenyl-oxirane gives the alcohol derivatives, HL1 and HL2, respectively. The 1:1 metal:ligand complex [Cu2(L1)2]2+ was found to be binuclear with the alcohol functions deprotonated to form alkoxide bridges between two CU(II) centres, Cu-N(1) 2.042(4), Cu-S(4) 2.452(2), Cu-S(7) 2.430(2), Cu-O(14) 1.927(4), Cu-O(14′) 1.922(4), Cu-Cu′ 3.0063(9) A, Cu-O-Cu′ 102.7(2)°. Magnetochemical data for this complex confirm antiferromagnetic coupling between the two Cu(II) centres with 2J = -417 ± 2 cm-1. With Ni(II) the complex [Ni(HL1)(CH3CO2)]+ can be isolated, the structure of which shows it to be a monomer with the ligand HL1 acting as a tetradentate ligand to the metal centre, Ni-N(1) 2.064(3), Ni-S(4) 2.3658(12), Ni-S(7) 2.3875(13), Ni-O(14) 2.061(3) A. A chelating acetate ligand completes the distorted octahedral geometry, Ni-O(16) 2.098(3), Ni-O(17) 2.102(3) A.
- Blake, Alexander J.,Danks, Jonathan P.,Fallis, Ian A.,Harrison, Andrew,Li, Wan-Sheung,Parsons, Simon,Ross, Steven A.,Whittaker, Gavin,Schroeder, Martin
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p. 3969 - 3976
(2007/10/03)
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- Solvents as phase transfer catalysts. Reaction of trimethylsulfonium iodide and solid potassium hydroxide in acetonitrile leading to an epoxide of benzophenone
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The kinetics of reactions of benzophenone with trimethylsulfonium iodide in acetonitrile in the presence of excess solid potassium hydroxide (KOH) are reported, and the kinetics of formation of products, 2,2-diphenyloxirane, 2,2-diphenylacrylonitrile, and N-(2-hydroxy-2,2-diphenyl)acetainide are also monitored. The effects of water, other cosolvents and quaternary ammonium salts are investigated. Initial rates are lower than rates of comparable reactions involving nitrile formation in the absence of sulfonium salts, and the epoxide reaches a concentration maximum before any nitrile forms. The results can be explained by initial formation of the anion [CH2CN]-, which reacts with the sulfonium salt to give Me2S+CH2- (ylide, leading to epoxide) before direct reaction of [CH2CN]- with benzophenone (leading to nitrile) can occur. Consequently, acetonitrile is acting as a phase transfer catalyst, aiding the transport of base (in a modified form) from the surface of the KOH to form the ylide.
- Bentley, T. William,Jones, Ray V.H.,Larder, Annette H.,Lock, Stephen J.
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p. 1407 - 1411
(2007/10/03)
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- Ruthenium(II)-bipyridine anchored montmorillonite-catalyzed oxidation of aromatic alkenes with tert-butyl hydroperoxide
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Bipyridylsitylated montmorillonite (abbreviated as bpy-mont) is prepared from H-montmorillonite and 6-(ethoxydimethylsilyl)-2,2'-bipyridine. Treatment of the bpy-mont with [RuCl2(CO)2](n) affords a novel clay catalyst including Ru(II)-bpy. The oxidation of aromatic alkenes with tert-BuOOH in the presence of the catalyst and Et3N mainly produces vic-bis(tert- butyldioxy)alkanes. A similar oxidation of 2,3-dimethyl-1,3-butadiene affords 1,4- and 1,2-bis(tert-butyldioxy)alkenes. In the absence of Et3N the oxidation of 1,1-diphenylethylene gives 2-tert-butyldioxy-1-hydrodioxy-1,1- diphenylethane as a major product. This catalyst is easily separated after the reactions and can be reused for oxidation.
- Nishimura, Takahiro,Onoue, Tomoaki,Ohe, Kouichi,Tateiwa, Jun-Ichi,Uemura, Sakae
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p. 4359 - 4362
(2007/10/03)
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- The radical chemistry of t-butyl hydroperoxide (TBHP) - Part 3 - Further studies on hydrocarbon activation
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Further aspects of the chemistry of TBHP in the presence of Fe(II) and Fe(III) species have been investigated. Now all the results previously reported with TBHP can be understood in terms of radical chemistry. Oxidation states of iron higher than Fe(III) are not involved.
- Barton, Derek H. R.,Le Gloahec, Valerie N.
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p. 15457 - 15468
(2007/10/03)
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- Development of a polymer bound Wittig reaction and use in multi-step organic synthesis for the overall conversion of alcohols to β-hydroxyamines
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An efficient combinatorial access to β-hydroxyamines suitable for automation is achieved by the mild oxidation of alcohols to aldehydes by polymer supported perruthenate (PSP), the subsequent clean olefination of the obtained aldehydes by polymer supported Wittig reagents followed by the epoxidation of the olefins by dimethyldioxirane (DMDO), and the final aminolysis of the epoxides with various amines is described.
- Bolli, Martin H.,Ley, Steven V.
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p. 2243 - 2246
(2007/10/03)
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- Process for preparing epoxides from carbonyl compounds using sulphonium or sulphoxonium ylides and intermediates useful therein
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A process for transforming a carbonyl compound into its corresponding epoxide, which comprises contacting the carbonyl compound with either trimethylsulphonium hydrogen sulphate and/or bis(trimethylsulphonium) sulphate or trimethylsulphoxonium hydrogen sulphate and/or bis(trimethylsulphoxonium) sulphate, in the presence of a base.
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- Palladium-Catalyzed Isomerization of Aryl-Substituted Epoxides: A Selective Synthesis of Substituted Benzylic Aldehydes and Ketones
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Aryl-substituted epoxides bearing multiple methyl substituants on the epoxide ring isomerize in the presence of 5 mol % Pd(OAc)2/PR3 (R = n-Bu, Ph) to form the corresponding benzylic aldehyde or ketone, with complete regioselectivity for the carbonyl compound formed via cleavage of the benzylic C-O bond. No allylic alcohols or products arising from alkyl migration are observed. Rapid reaction rates and nearly quantitative yields are obtained, even with highly sterically hindered epoxides, using tri-n-butylphosphine as ligand and tert-butyl alcohol as solvent. 2-Aryl-substituted epoxides with two methyl substituents on C3 are completely unreactive, consistent with an oxidative addition/β-hydride elimination mechanism. Catalyst variation studies show that both Pd(OAc)2 and PR3 are essential for optimal activity and that palladium catalysts formed in this manner are superior to other Pd(0) catalysts (e.g., Pd(PPh3)4). The reactivity of catalytic Pd(OAc)2/PR3 toward multiply-substituted epoxides is compared to traditional Lewis acid catalysts; the former is found to be much more selective for isomerization without skeletal rearrangement. A mechanistic rationale involving turnover-limiting SN2-like attack of Pd(0) at the benzylic carbon is proposed.
- Kulasegaram, Sanjitha,Kulawiec, Robert J.
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p. 6547 - 6561
(2007/10/03)
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- Novel photo-rearrangements of 3,3,5-triaryl-1,2-dioxolanes: Evidence for 1,5-dioxyl diradical intermediates
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3-(p-Methoxyphenyl)-substituted 1,2-dioxolanes undergo novel photo-rearrangements to afford 1,3-diaryl-3-(p-methoxyphenoxy)propan-1-ones along with 1,3,3-triaryl-3-hydroxypropan-1-ones via 1,5-dioxyl diradical intermediates.
- Kamata, Masaki,Nishikata, Yasuhiro,Kato, Mitsuaki
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p. 2407 - 2408
(2007/10/03)
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- Methyltrioxorhenium(VII)-katalysierte Epoxydierung von Alkenen mit Harnstoff-Wasserstoffperoxid
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Keywords: Asymmetrische Synthesen; Epoxidierungen; Katalyse; Komplexe mit Sauerstoffliganden; Rheniumverbindungen
- Adam, Waldemar,Mitchell, Catherine M.
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p. 578 - 581
(2007/10/03)
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- Reaction of diphenylsulfonium methylide with carbonyl compounds in non-basic media
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Diphenylsulfonium methylide was formed by fluoride-induced desilylation of diphenyl[(trimethylsilyl)methyl]sulfonium triflate with cesium fluoride in dimethyl sulfoxide and allowed to react with carbonyl compounds in situ to give oxiranes.
- Hioki,Tani,Sato
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p. 649 - 650
(2007/10/02)
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- Thermal reactions of oxiranes
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The pyrolytic reactions of tetramethylethylene oxide, cyclopentene oxide, cyclohexene oxide, cyclooctene oxide, 1,2-epoxyethylbenzene, 1,2-epoxy-2-phenylpropane, 1,2-epoxy-1-phenylpropane, and 1,2-epoxy-1,2-diphenylethane were investigated at 600 deg C using a conventional pyrolysis flow system.The products are mainly due to thermal cleavage of the oxirane ring followed by rearrangement to give carbonyl compounds.
- Oyewale, A. O.,Aitken, R. A.
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p. 919 - 922
(2007/10/02)
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- The in situ generation and use of iodomethyllithium for the one-carbon homologation of boronic esters and epoxide formation from carbonyl compounds
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Iodomethyllithium is shown to be an effective reagent for the one-carbon homologation of oxygenated boronic esters. The use of iodomethyllithium for the preparation of pinacol iodomethaneboronate and for the synthesis of epoxides from carbonyl compounds is also discussed.
- Wallace,Battle
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p. 127 - 133
(2007/10/02)
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