- Mechanistic Studies of the TRIP-Catalyzed Allylation with Organozinc Reagents
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3,3-Bis(2,4,6-triisopropylphenyl)-1,1-binaphthyl-2,2-diyl hydrogenphosphate (TRIP) catalyzes the asymmetric allylation of aldehydes with organozinc compounds, leading to highly valuable structural motifs, like precursors to lignan natural products. Our previously reported mechanistic proposal relies on two reaction intermediates and requires further investigation to really understand the mode of action and the origins of stereoselectivity. Detailed ab initio calculations, supported by experimental data, render a substantially different mode of action to the allyl boronate congener. Instead of a Br?nsted acid-based catalytic activation, the chiral phosphate acts as a counterion for the Lewis acidic zinc ion, which provides the activation of the aldehyde.
- Hartmann, Peter E.,Lazzarotto, Mattia,Pletz, Jakob,Tanda, Stefan,Neu, Philipp,Goessler, Walter,Kroutil, Wolfgang,Boese, A. Daniel,Fuchs, Michael
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p. 9672 - 9679
(2020/09/03)
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- Cyanide-Free One-Pot Synthesis of Methacrylic Esters from Acetone
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Methacrylic esters, represented by methyl methacrylate (MMA), are widely used as commodity chemicals. Here, the one-pot synthesis of methacrylic esters from acetone, a haloform and alcohols in the presence of an organic base is described. Using DBU as the organic base for the reaction of acetone, chloroform and methanol in acetonitrile afforded MMA in 66 % yield. When the solvent was replaced by benzonitrile, the product MMA was successfully purified by distillation. Applicability of this process to various alcohols was also investigated to show ethyl, phenyl, CF3CH2, and n-C6F13CH2CH2 esters were obtained in moderate yields. The use of bromoform instead of chloroform resulted in the improvement of the yield, for example, methyl and n-C6F13CH2CH2 esters up to 81 and 70 %, respectively. The reaction with deuterated starting materials acetone-d6 and MeOH-d4, with DBU in acetonitrile afforded deuterated MMA (MMA-d8) in 70 % yield.
- Koyama, Minoru,Kawakami, Takafumi,Okazoe, Takashi,Nozaki, Kyoko
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p. 10913 - 10917
(2019/08/02)
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- Switchable C-H Functionalization of N-Tosyl Acrylamides with Acryloylsilanes
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A controllable Rh-catalyzed protocol to access alkylation and alkenylation-annulation of N-tosyl acrylamide with acryloyl silane is reported. In contrast to the directing group or catalyst-dependent divergent sp2 C-H alkylation/alkenylation, the intrinsic property of acryloylsilane allows the switchable reaction manifold, thereby affording either alkylation or annulation products with slight modification of the reaction conditions.
- Song, Shengjin,Lu, Ping,Liu, Huan,Cai, Sai-Hu,Feng, Chao,Loh, Teck-Peng
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supporting information
p. 2869 - 2872
(2017/06/13)
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- A mild method for the replacement of a hydroxyl group by halogen. 1. Scope and chemoselectivity
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α-Chloro-, bromo- and iodoenamines, which are readily prepared from the corresponding isobutyramides have been found to be excellent reagents for the transformation of a wide variety of alcohols or carboxylic acids into the corresponding halides. Yields are high and conditions are very mild thus allowing for the presence of sensitive functional groups. The reagents can be easily tuned allowing therefore the selective monohalogenation of polyhydroxylated molecules. The scope and chemoselectivity of the reactions have been studied and reaction mechanisms have been proposed.
- Munyemana, Fran?ois,George, Isabelle,Devos, Alain,Colens, Alain,Badarau, Eduard,Frisque-Hesbain, Anne-Marie,Loudet, Aurore,Differding, Edmond,Damien, Jean-Marie,Rémion, Jeanine,Van Uytbergen, Jacqueline,Ghosez, Léon
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p. 420 - 430
(2015/12/31)
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- Rhodium(iii)-catalyzed C-H allylation of electron-deficient alkenes with allyl acetates
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Rhodium-catalyzed C-H allylation of acrylamides with allyl acetates is reported. The use of weakly coordinating directing group resulted in high reaction efficiency, broad functionality tolerance and excellent γ-selectivity, which opens a new synthetic pathway for the access of 1,4-diene skeletons.
- Feng, Chao,Feng, Daming,Loh, Teck-Peng
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supporting information
p. 342 - 345
(2015/01/09)
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- Direct ortho-thiolation of arenes and alkenes by nickel catalysis
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The direct thiolation of arenes and alkenes with diaryl disulfides was developed by nickel catalysis. The reaction displayed exceptional compatibility with a wide range of functional groups to regioselectively give the diaryl sulfides and alkenyl sulfides in high yields.
- Lin, Cong,Li, Danyang,Wang, Binjie,Yao, Jinzhong,Zhang, Yuhong
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supporting information
p. 1328 - 1331
(2015/03/14)
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- Aerobic oxidative esterification of aldehydes with alcohols by gold-nickel oxide nanoparticle catalysts with a core-shell structure
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Oxidative esterification of aldehydes with alcohols proceeds with high efficiency in the presence of molecular oxygen on supported gold-nickel oxide (AuNiOx) nanoparticle catalysts. The method is environmentally benign because it requires only molecular oxygen as the terminal oxidant and gives water as the side product. The AuNiOx nanoparticles have a core-shell structure, with the Au nanoparticles at the core and the surface covered by highly oxidized NiOx. Aerobic oxidative esterification of methacrolein in methanol to methyl methacrylate is an important industrial method for the production of polymethyl methacrylate.
- Suzuki, Ken,Yamaguchi, Tatsuo,Matsushita, Ken,Iitsuka, Chihiro,Miura, Junichi,Akaogi, Takayuki,Ishida, Hiroshi
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p. 1845 - 1849
(2013/09/02)
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- H-transfer reaction during decomposition of N-(2-methylpropyl)- N-(1-diethylphosphono-2,2-dimethylpropyl)-N-oxyl (SG1)-based alkoxyamines
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Thermal decomposition of four tertiary N-(2-methylpropyl)-N-(1- diethylphosphono-2,2-dimethylpropyl)-N-oxyl (SG1)-based alkoxyamines (SG1-C(Me)2-C(O)-OR, R = Me, tBu, Et, H) has been studied at different experimental conditions using 1/su
- Edeleva, Mariya,Marque, Sylvain R.A.,Kabytaev, Kuanish,Guillaneuf, Yohann,Gigmes, Didier,Bagryanskaya, Elena
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p. 1323 - 1336
(2013/04/10)
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- METHOD FOR CONTINUOUSLY PREPARING CARBOXYLIC ACID ESTER
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A method for continuously preparing a carboxylic acid ester is disclosed. In the method of the present invention, a vertical reactor is filled with a solid catalyst, a carboxylic acid and an alcohol are introduced into a lower part of the vertical reactor, esterification is performed to form an esterized mixture, the esterized mixture is output from an upper part of the vertical reactor, and distillation is performed to isolate the carboxylic acid ester. The method of the present invention is simple, easily controlled and environmental friendly, and has significantly high conversion rate and selectivity.
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Paragraph 0024; 0026
(2013/11/19)
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- Dependence of thermal stability on molecular structure of RAFT/MADIX agents: A kinetic and mechanistic study
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The thermal decomposition of different classes of RAFT/MADIX agents, namely dithioesters, trithiocarbonates, xanthates, and dithiocarbamates, were investigated through heating in solution. It was found that the decomposition behavior is complicated interplay of the effects of stabilizing Z-group and leaving R-group. The mechanism of the decomposition is mainly through three pathways, i.e., β-elimination, α-elimination, and homolysis of dithiocarbamate (particularly for universal RAFT agent). The most important pathway is the β-elimination of thiocarbonylthio compounds possessing β-hydrogen, leading to the formation unsaturated species. For the leaving group containing solely α-hydrogen, such as benzyl, α-elimination takes place, resulting in the formation of (E)-stilbene through a carbene intermediate. Homolysis occurs specifically in the case of a universal RAFT agent, in which a thiocarbonyl radical and an alkylthio radical are generated, finally forming thiolactone through a radical process. The stabilities of the RAFT/MADIX agents are investigated by measuring the apparent kinetics and activation energy of the thermal decomposition reactions. Both Z-group and R-group influence the stability of the agents through electronic and steric effects. Lone pair electron donating heteroatoms of Z-group show a remarkable stabilizing effect while electron withdrawing substituents, either in Z- or R-group, tends to destabilize the agent. In addition, bulkier or more β-hydrogens result in faster decomposition rate or lower decomposition temperature. Thus, the stability of the RAFT/MAIDX agents decreases in the order where R is (with identical Z = phenyl) -CH2Ph (5) > -PS (PS-RAFT 15) > -C(Me)HPh (2) > -C(Me)2C(=O)OC2H5 (7) > -C(Me)2Ph(1) > -PMMA (PMMA-RAFT 16) > -C(Me) 2CN (6). For those possessing identical leaving group such as 1-phenylethyl, the stability decreases in the order of O-ethyl (11) > -N(CH2CH3)2 (13) > -SCH(CH3)Ph (8) > -Ph (2) > -CH2Ph (4) > -PhNO2 (3). These results consort with the chain transfer acitivities measured by the CSIRO group and agree well with the ab initio theoretical results by Coote. In addition, the difference between thermal stabilities of the universal RAFT agents at neutral and protonated states has also been demonstrated.
- Zhou, Yanwu,He, Junpo,Li, Changxi,Hong, Linxiang,Yang, Yuliang
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experimental part
p. 8446 - 8457
(2012/03/12)
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- Aminodifluorosulfinium salts: Selective fluorination reagents with enhanced thermal stability and ease of handling
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Diethylaminodifluorosulfinium tetrafluoroborate (XtalFluor-E) and morpholinodifluorosulfinium tetrafluoroborate (XtalFluor-M) are crystalline fluorinating agents that are more easily handled and significantly more stable than Deoxo-Fluor, DAST, and their analogues. These reagents can be prepared in a safer and more cost-efficient manner by avoiding the laborious and hazardous distillation of dialkylaminosulfur trifluorides. Unlike DAST, Deoxo-Fluor, and Fluolead, XtalFluor reagents do not generate highly corrosive free-HF and therefore can be used in standard borosilicate vessels. When used in conjunction with promoters such as Et3N3HF, Et3N2HF, or DBU, XtalFluor reagents effectively convert alcohols to alkyl fluorides and carbonyls to gem-difluorides. These reagents are typically more selective than DAST and Deoxo-Fluor and exhibit superior performance by providing significantly less elimination side products.
- Lheureux, Alexandre,Beaulieu, Francis,Bennett, Christopher,Bill, David R.,Clayton, Simon,Laflamme, Franois,Mirmehrabi, Mahmoud,Tadayon, Sam,Tovell, David,Couturier, Michel
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supporting information; experimental part
p. 3401 - 3411
(2010/07/07)
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- Development of a scalable synthesis of GSK183390A, a PPAR α/γ agonist
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A scalable synthesis of GSK183390A, a PPAR α/γ agonist, is described. This synthesis is highlighted by (1) a regioselective formal 1,3-dipolar cycloaddition reaction between an enamine and a nitrile inline dipole to form a 1,3,5-trisubstmited pyrazole and (2) a regioselective amidomethylation of an o-cresol derivative using 2-chloro-JV- hydroxymethylacetamide.
- Oh, Lynette M.,Wang, Huan,Shilcrat, Susan C.,Hermann, Robert E.,Patience, Daniel B.,Spoors, P. Grant,Sisko, Joseph
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p. 1032 - 1042
(2012/12/30)
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- Catalyst and process for preparing carboxylic acid esters
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A catalyst and a process for preparing carboxylic acid esters from an aldehyde and an alcohol in the presence of molecular oxygen are disclosed. The catalyst comprises metals supported on a silica-containing support, wherein the metals consist essentially of palladium, lead, an alkali or alkaline earth metal, and at least one of niobium and zirconium. The process for preparing a carboxylic acid ester comprises reacting an aldehyde with an alcohol in the presence of molecular oxygen and the aforementioned catalyst.
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- Cosmetic preparations and use thereof, containing polyethylene waxes with improved organoleptic properties
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Cosmetic preparations comprising polyethylene waxes having improved organoleptic properties Cosmetic preparations and toothpastes, comprising polyethylene waxes, in particular micronized polyethylene waxes with improved organoleptic properties prepared by (co)polymerization of ethylene under high-pressure conditions using an aliphatic or alicyclic ketone as molecular weight regulator.
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- Preparation of preparing substituted indanones
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a process for the preparation of indanones of the formula II from, indanones of the formula I or of indanones of the formula IIa from indanones of the formula Ia comprises reacting an indanone of the formula I or Ia with a coupling component.
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- Ruthenium-catalyzed carbonylation of allene: Direct synthesis of methacrylates and methacrylamides
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Carbonylation reactions of allene in alcohols and amines in the presence of a ruthenium carbonyl catalyst under mild conditions gave methacrylates and methacrylamides, respectively, in good yields with an atom economy of 100%.
- Zhou, Da-Yang,Yoneda, Eiji,Onitsuka, Kiyotaka,Takahashi, Shigetoshi
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p. 2868 - 2869
(2007/10/03)
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- PRODUCTION OF METHACRYLIC ACID ESTERS BY THE HETEROGENEOUS CATALYTIC OXIDATION OF α-METHYLACROLEIN IN THE PRESENCE OF ALCOHOLS
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The possibility of producing methacrylic acid esters by the heterogeneous catalytic oxidation (phosphorus-molybdenum catalyst) of α-methylacrolein in the presence of different aliphatic alcohols has been shown.The general relationships governing the successive conjugated reactions of oxidation and esterification have been determined.
- Linde, V. R.,Kir'Yakova, O. V.,Syurakshin, A. V.
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p. 513 - 517
(2007/10/02)
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- Pentacarbonylmanganese enolate and dienolate complexes. Preparative and mechanistic considerations
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Reactions of pentacarbonyl manganate anion with 4-halocrotonate esters or 2-halocarboxylate esters result in a complex set of inorganic and organic products, usually including the expected dienolate (or enolate) complexes.The reaction variables include the counterion, solvent, and halo group.The mechanism of the reaction has been investigated by conducting a thorough characterization of the reaction products under various conditions and also by carrying out model reactions.One can rationalize most of the non-organometallic products using either a radical or carbanion mechanism, but the latter seems to fit the available data better.Experimental procedures for optimizing the yield of the organometallic dienolate or enolate complexes have been worked out.
- Masters, Andrew P.,Sorensen, Ted S.
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p. 492 - 501
(2007/10/02)
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- PYROLYSIS OF α-ACYL SUBSTITUTED ETHYL PHENYL SULFOXIDE
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The effect of pyrolysis of the acyl group substituted on α-position carbon in S-ethyl group of ethyl phenyl sulfoxide was investigated by using two kinds of substrates, 1-ethoxycarbonylethyl phenyl sulfoxide (1) and 1-ethoxycarbonyl-1-methylethyl phenyl sulfoxide (2) together with 2-methoxycarbonylethyl phenyl sulfoxide (4).The rate of pyrolysis of (1) was found to be about 740 ca. 890 times faster than that of ethyl phenyl sulfoxide (5), while (2) was 5700 times faster.The rate enhancement effect on α-ethoxycarbonyl group was larger than that on β-methoxycarbonyl group.Large deuterium kinetic isotope effect (kH/kD=5.5 for PhS(O)C(CD3)2CO2Et (3)) was observed.Activation energy for (2) is about 110 kJ/mol, which is just about the same as that of (5) (108 kJ/mol), while activation entropy lies in ca. 1 Jdeg-1 mol-1.Hammett plot for substituted (2) gave ?=0.69.These kinetic results reveal that the pyrolysis of the sulfoxides proceeds via a loose transition state involving advanced C-S bond cleavage.The remarkably large rate enhancement by α-carbonyl group might be due mainly to the conjugation of that group and developing double bond acidifying the β-proton in the transition state.Key words: Pyrolysis; elimination; mechanism; isotope effect; kinetics; sulfoxide,
- Tsukurimichi, Eiichi,Yoshimura, Toshiaki,Yoshizawa, Masaki,Itakura, Hiromi,Shimasaki, Choichiro
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p. 113 - 120
(2007/10/02)
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- A NEW SYNTHESIS OF α-METHYLENE CARBONYL COMPOUNDS
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α-Methylene carbonyl compounds are regioselectively prepared by the reaction of α-nitroketones or α-nitroesters with 37percent formaldehyde in the presence of a catalytic amount of weak bases followed by acetylation, denitration with Bu3SnH, and elimination of acetic acid.
- Ono, Noboru,Miyake, Hideyoshi,Fujii, Masayuki,Kaji, Aritsune
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p. 3477 - 3480
(2007/10/02)
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- Carbonates carrying cyclic carbonate groups
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The invention relates to new industrial products of the general formula STR1 a process for the manufacture of these products and their application in hydrometallurgy. According to the invention, R is in particular an alkyl, cycloalkyl, aryl, aralkyl, carboxylate, polyoxyethylene, polyester or polycarbonate group. The process consists in reacting an alcohol or a polyol, ROH, with 2,3-dioxycarbonylpropyl chloroformate, at between -10° and +20° C., in the presence of an acid acceptor. Application: the compounds according to the invention are extraction agents for hydrometallurgy, which can be used in dilute solution.
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