- Reaction of dicarbomethoxycarbene with thiophene derivatives
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Photolysis of derivatives of dimethylmalonate thiophene-S,C-ylide provides dicarbomethoxycarbene, which can react with thiophene to form dimethyl (2-thienyl)malonate. By generation of dicarbomethoxycarbene from the dibenzothiophene-based ylide in neat thi
- Jenks, William S.,Heying, Melanie J.,Stoffregen, Stacey A.,Rockafellow, Erin M.
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Read Online
- Synthesis and crystal structure analysis of methyl 2-hydroxyimino-3-phenyl- propionate
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As precursors of α-amino acids, methyl 2-hydroxyimino-3-phenyl- propionate (F.W. 193.20) was synthesized, characterized by 1H NMR, IR, element analysis and confirmed by X-ray crystal structure analysis. This compound crystallizes in monoclinic
- Li, Xiao-Liu,Zhen, Xiao-Li,Han, Jian-Rong,Liu, Shouxin
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Read Online
- Cobalt-Catalyzed Highly Regioselective Three-Component Arylcarboxylation of Acrylate with Aryl Bromides and Carbon Dioxide
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Cobalt-catalyzed regioselective three-component arylcarboxylation of acrylate with aryl bromides and carbon dioxide has been developed. The reaction is carried out by using cobalt chloride as a precatalyst and zinc powder as a reducing reagent under CO2 (1 atm) at 40 °C. A range of aryl bromides are used for this reaction, leading to a series of valuable carboxylic acids with high regioselectivity and functional-group compatibility. Mechanistic experiments and DFT calculations indicate that this arylcarboxylation reaction involves the reaction of CO2 with a cobalt enolate intermediate to form the C?C bond.
- Hang, Wei,Liang, Nianjie,Liu, Yuzhou,Xi, Chanjuan
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p. 4941 - 4946
(2021/10/30)
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- Reductive Knoevenagel Condensation with the Zn-AcOH System
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An efficient gram-scale one-pot approach to 2-substituted malonates and related structures is developed, starting from commercially available aldehydes and active methylene compounds. The technique combines Knoevenagel condensation with the reduction of the C=C bond in the resulting activated alkenes with the Zn-AcOH system. The relative ease with which the C=C bond reduction occurs can be traced to the accepting abilities of the substituents in the intermediate arylidene malonates.
- Ivanov, Konstantin L.,Melnikov, Mikhail Ya.,Budynina, Ekaterina M.
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p. 1285 - 1291
(2020/11/13)
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- Au-Cavitand Catalyzed Alkyne-Acid Cyclizations
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Supramolecular cavitands that contain inwardly directed functional groups have yielded specialized transformations and trapping of reactive intermediates. A recently reported 3-wall Au cavitand provides exciting opportunities for supramolecular catalysis. In this study, a variety of substituted γ-alkynoic acids were reacted to give lactones. The interaction of peripheral “R” groups revealed differential catalyst behavior. Extremely large and small groups reacted with appreciable rate. Intermediate sized groups however, slowed significantly: giving support that size-specific binding is at play when using cavitands as a scaffold for gold catalysis. These results serve as some of the first evidence of the interplay between substrate and cavitand interior in the catalytic sphere.
- Ho, Tam D.,Schramm, Michael P.
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supporting information
p. 5678 - 5684
(2019/08/21)
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- Room-Temperature Benzylic Alkylation of Benzylic Carbonates: Improvement of Palladium Catalyst and Mechanistic Study
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The palladium catalyst for the nucleophilic substitution of benzyl carbonates was improved by using 1,1′-bis(diisopropylphosphino)ferrocene (DiPrPF) as the ligand. The [Pd(η3-C3H5)(cod)]BF4-DiPrPF catalyst allows the benzylic substitution with soft carbanions to proceed even at 30 °C, affording the desired products in high yields (up to 99% yield). Thermally unstable pyridylmethyl esters are employable as the electrophilic substrates for the benzylic alkylation with the improved catalyst. Furthermore, we investigated the mechanism of the catalytic benzylic alkylation by means of DiPrPF ligand. The palladium(0) complex bearing DiPrPF activates the benzylic C-O bond to form the (benzyl)palladium(II) intermediate at room temperature. The coordination mode of the benzyl ligand would be equilibrium between the η1- and η3-manner. The nucleophile would preferentially react with the η3-benzyl ligand to give the desired product.
- Kuwano, Ryoichi,Yokogi, Masashi,Sakai, Ken,Masaoka, Shigeyuki,Miura, Takashi,Won, Sungyong
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p. 1568 - 1579
(2019/09/04)
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- Palladium-Catalyzed [3 + 2]-C-C/N-C Bond-Forming Annulation
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The synthesis of bi- and tricyclic structures incorporating pyrrolidone rings is disclosed, starting from resonance-stabilized acetamides and cyclic α,β-unsaturated-γ-oxycarbonyl derivatives. This process involves an intermolecular Tsuji-Trost allylation/intramolecular nitrogen 1,4-addition sequence. Crucial for the success of this bis-nucleophile/bis-electrophile [3 + 2] annulation is its well-defined step chronology in combination with the total chemoselectivity of the former step. When the newly formed annulation product carries a properly located o-haloaryl moiety at the nitrogen substituent, a further intramolecular keto α-arylation can join the cascade, thereby forming two new cycles and three new bonds in the same synthetic operation.
- Liu, Yang,Mao, Zhongyi,Pradal, Alexandre,Huang, Pei-Qiang,Oble, Julie,Poli, Giovanni
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supporting information
p. 4057 - 4061
(2018/07/15)
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- Design and synthesis of malonamide derivatives as antibiotics against methicillin-resistant staphylococcus aureus
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Methicillin-resistant Staphylococcus aureus (MRSA) is a serious threat to humans. Most existing antimicrobial drugs, including the β-lactam and quinoxiline classes, are not effective against MRSA. In this study, we synthesized 24 derivatives of malonamide, a new class of antibacterial agents and potentiators of classic antimicrobials. A derivative that increases bacterial killing and biofilm eradication with low cell toxicity was created.
- Su, Jung-Chen,Huang, Yu-Ting,Chen, Chang-Shi,Chiu, Hao-Chieh,Shiau, Chung-Wai
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- Intermolecular Reductive Couplings of Arylidene Malonates via Lewis Acid/Photoredox Cooperative Catalysis
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A cooperative Lewis acid/photocatalytic reduction of arylidene malonates yields a versatile radical anion species. This intermediate preferentially undergoes intermolecular radical-radical coupling reactions, and not the conjugate addition-dimerization reactivity typically observed in the single-electron reduction of conjugate acceptors. Reported here is the development of this open-shell species in intermolecular radical-radical cross couplings, radical dimerizations, and transfer hydrogenations. This reactivity underscores the enabling modularity of cooperative catalysis and demonstrates the utility of stabilized enoate-derived radical anions in intermolecular bond forming reactions.
- McDonald, Benjamin R.,Scheidt, Karl A.
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p. 6877 - 6881
(2018/11/02)
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- Development of efficient palladium catalysts for alkoxycarbonylation of alkenes
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Herein, we report a general and efficient Pd-catalysed alkoxycarbonylation of sterically hindered and demanding olefins including a variety of tri-, tetra-substituted and 1,1-disubstituted alkenes. In the presence of 1,3-bis(tert-butyl(pyridin-2-yl)phosphanyl)propane L3 or 1,4-bis(tert-butyl(pyridin-2-yl)phosphanyl)butane L4 the desired esters are obtained in good yields and selectivities. Similar transformation is obtained using tertiary ether as showcased in the carbonylation of MTBE to the corresponding linear ester in high yield and selectivity.
- Liu, Jiawang,Dong, Kaiwu,Franke, Robert,Neumann, Helfried,Jackstell, Ralf,Beller, Matthias
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supporting information
p. 12238 - 12241
(2018/11/21)
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- Catalytic Use of Low-Valent Cationic Gallium(I) Complexes as π-Acids
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Transformations of alkene and alkyne substrates relevant to π-Lewis acid catalysis have been performed using low-valent Ga(I) species for the first time. [Ga(I)(PhF)2]+[Al(ORF)4]? and gallium dichloride (i. e. [Ga(I)]+[GaCl4]?) proved to be efficient catalysts for cycloisomerizations, Friedel-Crafts reactions, transfer hydrogenations, and reductive hydroarylations. Their activity is compared to more common Ga(III) complexes. This study shows that even the readily available and yet overlooked gallium dichloride salt can be a more active π-Lewis acid catalyst than gallium trichloride or other Ga(III) species. (Figure presented.).
- Li, Zhilong,Thiery, Guillaume,Lichtenthaler, Martin R.,Guillot, Régis,Krossing, Ingo,Gandon, Vincent,Bour, Christophe
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supporting information
p. 544 - 549
(2017/11/27)
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- Intermolecular Photocatalytic C-H Functionalization of Electron-Rich Heterocycles with Tertiary Alkyl Halides
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The coupling of tertiary alkyl halides with electron-rich arenes is promoted by visible-light photoredox catalysis. Tris[2-phenylpyridinato-C2,N]iridium(III) [Ir(ppy)3] was the optimal catalyst, enabling direct reduction of the halide from the excited state, and thereby eliminating the requirement for a stoichiometric electron donor. High yields were obtained when the aromatic component was used in excess, although equimolar amounts afforded only slightly diminished yields. The reaction tolerates a number of functional groups, including allyl, ester, amide, or carbamate. The efficiency of this reaction has been improved through demonstration of scale-up in flow, and a new substituted Ir(ppy)3 derivative was isolated and characterized.
- Swift, Elizabeth C.,Williams, Theresa M.,Stephenson, Corey R. J.
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supporting information
p. 754 - 758
(2016/03/09)
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- Palladium catalyzed direct benzylation/allylation of malonates with alcohols-: In situ C-O bond activation
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High step- and atom-economy are the endlessly pursued in organic and pharmaceutical syntheses. Herein, a new method for directly coupling benzyl/allyl alcohols with malonates via a palladium catalyzed Tsuji-Trost type reaction was developed. The reaction was carried out in an organic carbonate solvent which would activate alcohols in situ, replacing the traditional pre-synthesized carbonates. The new process demonstrated high efficiency, high selectivity and high generality. A wide variety of mono-substituted and bis-substituted malonates were selectively produced under different conditions, and this method represents a more step- and atom-economical and environmentally benign synthetic protocol.
- Cao, Xueqin,Zhang, Yugen
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supporting information
p. 2638 - 2641
(2016/05/24)
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- Dimethyl malonate/LHMDS system as a new protocol for generating methyl formate anion (-COOMe) in the condensed-phase Dedicated to Professor Charles H. DePuy (1927-2013)
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The treatment of dimethyl malonate with LHMDS in anhydrous THF (condensed-phase) generates, in addition to the expected corresponding lithium enolate, methyl formate anion (or methoxycarbonyl anion, -COOMe) which can react with several electrophiles to give corresponding methoxycarbonyl derivatives by nucleophilic substitution reaction.
- Di Bussolo, Valeria,Princiotto, Salvatore,Martinelli, Elisa,Bordoni, Vittorio,Crotti, Paolo
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p. 1644 - 1647
(2016/04/04)
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- Palladium-Catalyzed Heck-type Domino Cyclization and Carboxylation to Synthesize Carboxylic Acids by Utilizing Chloroform as the Carbon Monoxide Source
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A palladium-catalyzed domino cyclization and carboxylation reaction for synthesis of a variety of carboxylic acids was developed, where chloroform was used as "carbon monoxide" source. The in situ generated neopentylpalladium species by Heck cyclization was efficiently trapped by dichlorocarbene to form a series of carboxylic acids. It was found that in this type of domino reaction CHCl3 is a convenient and safe alternation for CO gas.
- Liu, Xianglei,Li, Bin,Gu, Zhenhua
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p. 7547 - 7554
(2015/08/18)
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- Reductive alkylation of active methylene compounds with carbonyl derivatives, calcium hydride and a heterogeneous catalyst
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A one-pot two-step reaction (Knoevenagel condensation - reduction of the double bond) has been developed using calcium hydride as a reductant in the presence of a supported noble metal catalyst. The reaction between carbonyl compounds and active methylene
- Guyon, Carole,Duclos, Marie-Christine,Sutter, Marc,Métay, Estelle,Lemaire, Marc
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p. 7067 - 7075
(2015/06/25)
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- The synthesis of α-azidoesters and geminal triazides
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Three simple methods for the synthesis of geminal triazides are described: Starting from 1) 3-oxocarboxylic acids, 2) iodomethyl ketones, or 3) terminal olefins, a range of triazidomethyl ketones can be constructed under mild oxidative reaction conditions by the use of IBX-SO3K, a sulfonylated derivative of 2-iodoxybenzoic acid (IBX), and NaN3 as an azide source. This is the first report of representatives of this novel class of triazide compounds: Despite their high nitrogen content, the geminal triazides are easy to handle, even when preparative-scale syntheses are performed. (Caution: These procedures still require protective measures!) The triazides are now broadly available for further studies regarding their properties and reactivity. Furthermore, we show how the method can be used to provide α-azidoesters, which are potential building blocks for amino acids. Either/or: Geminal triazides are rapidly constructed with broad scope by the use of oxocarboxylic acids, iodomethyl ketones, or terminal olefins as starting substrates in oxidative azidations with a mild derivative of 2-iodoxybenzoic acid and sodium azide. Along with this little-studied class of organic azides, α-azidoesters were also synthesized.
- Klahn, Philipp,Erhardt, Hellmuth,Kotthaus, Andreas,Kirsch, Stefan F.
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supporting information
p. 7913 - 7917
(2014/08/05)
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- Creation through immobilization: A new family of high performance heterogeneous bifunctional iminophosphorane (BIMP) superbase organocatalysts
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An immobilized chiral bifunctional iminophosphorane superbase organocatalyst has been developed and applied in a range of challenging enantioselective reactions. A unique feature of this novel catalytic system is that the final step creation of the iminophosphorane occurs at the point of immobilization. The utility of the immobilized catalyst system was demonstrated in the nitro-Mannich reaction of ketimines as well as the conjugate addition of high pKa 1,3-dicarbonyl pro-nucleophiles to nitrostyrene. Catalyst recycling was also demonstrated.
- Goldys, Anna M.,Nez, Marta G.,Dixon, Darren J.
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p. 6294 - 6297
(2015/02/05)
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- α-Hydroxylation of 1,3-dicarbonyl compounds catalyzed by polymer-incarcerated gold nanoclusters with molecular oxygen
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α-Hydroxylation of 1,3-dicarbonyl compounds was successfully catalyzed by carbon-stabilized polymer-incarcerated gold nanoclusters (PI/CB-Au). The reaction proceeded under mild conditions using molecular oxygen as oxidant with wide substrate scopes and the catalyst could be recovered and reused by a simple operation. The control experiments and the reaction monitoring revealed that α-peroxide compounds were reaction intermediates, and PI/CB-Au also catalyzed isomerization.
- Miyamura, Hiroyuki,Kobayashi, Shu
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supporting information
p. 976 - 978
(2012/10/30)
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- Novel Pyrimidine- And Triazine-Hepcidine Antagonists
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The present invention relates to new hepcidin antagonists, pharmaceutical compositions containing them and the use thereof as a drug, in particular for the treatment of iron metabolism disorders such as, in particular, iron deficiency diseases and anaemia, in particular anaemia associated with chronic inflammatory disease (ACD: anaemia of chronic disease and AI: anaemia of inflammation).
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- Synthetic and mechanistic studies of metal-free transfer hydrogenations applying polarized olefins as hydrogen acceptors and amine borane adducts as hydrogen donors
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Metal-free transfer hydrogenation of polarized olefins (RR′ CCEE′: R, R′ = H or organyl, E, E′ = CN or CO2Me) using amine borane adducts RR′NH-BH3 (R = R′ = H, AB; R = Me, R′ = H, MAB; R = tBu, R′ = H, tBAB; R = R′ = Me, DMAB) as hydrogen donors, were studied by means of in situ NMR spectroscopy. Deuterium kinetic isotope effects and the traced hydroboration intermediate revealed that the double H transfer process occurred regio-specifically in two steps with hydride before proton transfer characteristics. Studies on substituent effects and Hammett correlation indicated that the rate determining step of the HN transfer is in agreement with a concerted transition state. The very reactive intermediate [NH2BH2] generated from AB was trapped by addition of cyclohexene into the reaction mixture forming Cy2BNH2. The final product borazine (BHNH)3 is assumed to be formed by dehydrocoupling of [NH2BH2] or its solvent stabilized derivative [NH2BH2]-(solvent), rather than by dehydrogenation of cyclotriborazane (BH2NH 2)3 which is the trimerization product of [NH 2BH2].
- Yang, Xianghua,Fox, Thomas,Berke, Heinz
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experimental part
p. 852 - 860
(2012/02/05)
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- Facile metal free regioselective transfer hydrogenation of polarized olefins with ammonia borane
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Transfer hydrogenation of polarized olefins bearing strongly electron-withdrawing groups on one side of the double bond was achieved with ammonia borane under mild conditions without using a catalyst. Mechanistic studies proved the character of the direct H transfers proceeding stepwise with a unique hydroboration intermediate and hydride before proton transfer.
- Yang, Xianghua,Fox, Thomas,Berke, Heinz
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p. 2053 - 2055
(2011/03/22)
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- Stereoselective synthesis of nipecotic acid derivatives via palladium-catalyzed decarboxylative cyclization of γ-methylidene-δ- valerolactones with imines
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(Chemical Equation Presented) A new synthetic method of multisubstituted nipecotic acid (piperidine-3-carboxylic acid) derivatives has been developed by way of palladium-catalyzed decarboxylative cyclization of γ-methylidene- δ-valerolactones with (mines.
- Shintani, Ryo,Murakami, Masataka,Hayashi, Tamio
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supporting information; experimental part
p. 457 - 459
(2009/07/11)
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- Sml2-mediated carbon-carbon bond fragmentation in a-aminomethyl malonates
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A new and efficient samarium diiodide-promoted carbon-carbon bond fragmentation reaction of α-aminomethyl malonates, taking place normally at room temperature and generating the corresponding deaminomethylation products In 74-94% yields, is reported. The presence of the amino group Is necessary for the success of the current transformation.
- Xu, Qiongfeng,Cheng, Bin,Ye, Xinshan,Zhai, Hongbin
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supporting information; experimental part
p. 4136 - 4138
(2009/12/30)
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- Multi-catalysis cascade reactions based on the methoxycarbonylketene platform: Diversity-oriented synthesis of functionalized non-symmetrical malonates for agrochemicals and pharmaceuticals
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In this paper we describe new multi-catalysis cascade (MCC) reactions for the one-pot synthesis of highly functionalized non-symmetrical malonates. These metal-free reactions are either five-step (olefination/hydrogenation/alkylation/ ketenization/esterif
- Ramachary, Dhevalapally B.,Venkaiah, Chintalapudi,Reddy, Y. Vijayendar,Kishor, Mamillapalli
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supporting information; scheme or table
p. 2053 - 2062
(2009/09/05)
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- Probing persistent intramolecular C-H· · ·X(X = O, S, Br, Cl, and F) bonding in solution using benzyl meldrum's acid derivatives
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Persistent intramolecular interactions between acidic C-H hydrogens and a variety of acceptors (X) (X = O, S, Br, Cl, and F) in solution were probed by 1H NMR experiments, using 5-benzyl Meldrum's acid derivatives. To bring about formation of i
- Fillion, Eric,Wilsily, Ashraf,Fishlock, Dan
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supporting information; experimental part
p. 1259 - 1267
(2009/06/28)
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- Electrochemical carboxylation of cinnamate esters in MeCN
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Electrochemical carboxylation of cinnamate esters has been carried out by cathodic reduction of C{double bond, long}C bond in an undivided cell equipped with Mg sacrificial anode and using MeCN saturated with CO2 as solvent. The yields and the
- Wang, Huan,Zhang, Kai,Liu, Ying-Zi,Lin, Mei-Yu,Lu, Jia-Xing
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p. 314 - 318
(2008/09/16)
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- Use of acetate as a leaving group in palladium-catalyzed nucleophilic substitution of benzylic esters
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The palladium complex prepared in situ from [Pd(η3-C3H5)(cod)]BF4 and bidentate phosphine DPPF was a good catalyst for the nucleophilic substitution of benzyl acetate. Significant acceleration of the palladium-catalyzed substitution was observed when an alcohol was employed as a reaction solvent. The palladium catalyst was effective for the benzylation of various stabilized carbanions, amines, and benzenesulfinate with benzylic acetates.
- Yokogi, Masashi,Kuwano, Ryoichi
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p. 6109 - 6112
(2008/03/12)
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- Transfer hydrogenation of activated C=C bonds catalyzed by ruthenium amido complexes: Reaction scope, limitation, and enantioselectivity
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(Chemical Equation Presented) It was found that the chemoselectivity could be completely switched from C=O to C=C bonds in the transfer hydrogenation of activated α,β-unsaturated ketones catalyzed by diamine-ruthenium complex. Moreover, this addition via metal hydride had been applied to the reduction of various activated olefins. The electron-withdrawing ability of functional groups substituted on C=C bonds at the α- or β-position had strong influence on the reactivity. In addition, a wide variety of chiral diamine-Ru(II)-(arene) systems was investigated to explore the asymmetric transfer hydrogenation of prochiral α,α-dicyanoolefins. Two parameters had been systematically studied, (i) the structure of the N-sulfonylated chiral diamine ligands, in which several chiral diamines substituted on the benzene ring of DPEN were first reported, and (ii) the structure of the metal precursors, and high enantioselectivitiy (up to 89% ee) at the β-carbon was obtained.
- Xue, Dong,Chen, Ying-Chun,Cui, Xin,Wang, Qi-Wei,Zhu, Jin,Deng, Jin-Gen
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p. 3584 - 3591
(2007/10/03)
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- A Facile one-pot benzylation of sodium enolates using trifluoromethanesulfonic anhydride and diphenyl sulfoxide
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A facile one-pot C-benzylation of various sodium enolates derived from methyl malonate, β-ketoesters, a β-cyanoester, a β-cyanosulfone, ketones and a carboxylic ester is reported. Reaction of alkoxydiphenylsulfonium salts formed by treating various benzyl alcohols with diphenyl sulfide bis(trifluoromethanesulfonate) (derived from trifluoromethanesulfonic anhydride and diphenyl sulfoxide) proceeded smoothly, and the corresponding C-benzylated products were afforded in good to high yields.
- Takuwa, Tomofumi,Minowa, Tomofumi,Fujisawa, Hidehiko,Mukaiyama, Teruaki
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p. 476 - 480
(2007/10/03)
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- A facile one-pot benzylation of sodium enolates using trifluoromethansulfonic anhydride and diphenyl sulfoxide
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A facile one-pot C-benzylation reaction proceeded smoothly and in good yields by treating various sodium enolates and benzyl alcohol with in situ generated alkoxy diphenyl sulfonium salt derived from trifluoromethansulfonic anhydride and diphenyl sulfoxide.
- Takuwa, Tomofumi,Onishi, Jim Yoshitaka,Matsuo, Jun-Ichi,Mukaiyama, Teruaki
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- Quantitating the effect of an ortho substituent on cyclization and intramolecular hydrogen-transfer reactions of aryl radicals
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Reduction of allyl 2-iodobenzyl malonates with triphenyltin hydrides generates aryl radicals that partition between 6-exo cyclization, 7-endo cyclization, and 1,5-hydrogen atom transfer. Rate constants for all of these processes are high (> 108 M-1 s-1), and the rates are only marginally reduced (33%) by the introduction of methyl group ortho to the reacting radical.
- Curran, Dennis P.,Fairweather, Neil
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p. 2972 - 2974
(2007/10/03)
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- Palladium-catalyzed nucleophilic benzylic substitutions of benzylic esters
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A palladium complex generated in situ from [Pd(η3-C3H5)(cod)]BF4 and DPPF is a good catalyst for benzylic alkylation of benzyl methyl carbonate with the carbanion of dimethyl malonates. The catalytic reaction is applicable to a wide range of the benzylations of benzylic esters with malonates. The catalytic activity was heavily affected by the bite angle of the bidentate phosphine ligand on palladium. DPEphos ligand is superior to DPPF in the case of palladium-catalyzed benzylic amination of benzylic esters. Copyright
- Kuwano, Ryoichi,Kondo, Yutaka,Matsuyama, Yosuke
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p. 12104 - 12105
(2007/10/03)
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- Electrooxidation of malonate and acetylacetate derivatives in the presence of halide ions
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β-Dicarbonyl compounds, such as dimethyl malonate derivatives and methyl acetoacetate derivatives, were electrooxidized in methanol in the presence of halogen ions to afford the corresponding dimethyl α-halomalonates and methyl α-halocarboxylates. Electrooxidation of bis(β-dimethoxycarbonyl) derivatives similarly afforded cyclic compounds and dihalides.
- Okimoto, Mitsuhiro,Takahashi, Yukio
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p. 2215 - 2219
(2007/10/03)
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- Preparation of phosphinodipeptide analogs as building blocks for pseudopeptides synthesis
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A simple and effective preparation of phosphinodipeptides, in good overall yields, has been developed. This one pot procedure, allowing the variation of the substituents in α and/or β position to the phosphorus atom and also in α position to the nitrogen atom, consists in the addition of alkyl hypophosphites to imines, followed by Michael-addition on acrylates. To show the value of phosphinodipeptides analogs 1 as synthetic intermediates, selective deprotections of the three functional groups are described.
- Cristau, Henri-Jean,Coulombeau, Agnès,Genevois-Borella, Arielle,Sanchez, Frédéric,Pirat, Jean-Luc
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p. 381 - 391
(2007/10/03)
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- Expanding the utility of proteases in synthesis: Broadening the substrate acceptance in non-coded amide bond formation using chemically modified mutants of subtilisin
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The strategy of combined site directed mutagenesis and chemical modification creates chemically modified mutants (CMMs) with greatly broadened substrate specificities. We have previously reported that the CMMs of subtilisin Bacillus lentus (SBL) are efficient catalysts for the coupling of both L- and D-amino acids. We now report that these powerful catalysts also allow amide bond formation between a variety of non-coded carboxylic acids, including β-alanine and β-amino homologues of phenylalanine, with both L- and D-amino acid nucleophiles. As a guide to enzyme efficiency, a hydrolysis assay indicating pH change has been employed. CMMs selected by this screen furnished higher yields of coupling products compared to the wild-type enzyme (WT). Furthermore, both WT and CMM enzymes allow highly stereoselective aminolysis of a meso diester with an amino acid amine. These results highlight the utility of CMMs in the efficient formation of non-coded amides as potential peptide isosteres.
- Khumtaveeporn, Kanjai,Ullmann, Astrid,Matsumoto, Kazutsugu,Davis, Benjamin G.,Jones
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p. 249 - 261
(2007/10/03)
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- Direct conversion of α,β-unsaturated nitriles into cyanohydrins using Mn(dpm)3 catalyst, dioxygen and phenylsilane
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Treatment of α,β-unsaturated nitriles with Mn(dpm)3 (3 mol%), PhSiH3 in isopropyl alcohol in the presence of oxygen resulted in reduction and α- and β-hydroxylation.
- Magnus, Philip,Scott, David A.,Fielding, Mark R.
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p. 4127 - 4129
(2007/10/03)
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- Conjugate intra- and intermolecular addition mediated by methoxide anion on polymeric support
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By treatment with methoxide anion on polymeric support (IRA 900), chiral β-oxo or β-sulphonyl-amides 2 bearing an α,β-unsaturated ester gave 3,4-disubstituted pyrrolidin-2-ones 3 as easily separable diastereomeric mixtures in good yield and moderate-to-good stereoselection. The polymeric reagent was also effective in promoting both intermolecular conjugate addition and alkylation reactions. (C) 2000 Elsevier Science Ltd.
- Fava,Galeazzi,Gonzalez-Rosende,Orena
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p. 8577 - 8580
(2007/10/03)
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- Chemo-enzymatic synthesis of chiral 2-substituted succinic acid derivatives
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Prochiral discrimination by the biocatalyst Alcalase, an enzyme preparation of subtilisin Carlsberg, was used to effect enantio- and regioselective monohydrolysis of a variety of (RS)-2-substituted succinate diesters to afford the corresponding half esters in modest to excellent enantiomeric excesses (>99%). Exploitation of malonate chemistry, as well as recycling of the unhydrolyzed isomer from the enantioselective hydrolysis, has resulted in a process which is both practical and economical.
- Bailey, Murray D.,Halmos, Ted,Adamson, Dan,Bordeleau, Josee,Grand-Maitre, Chantal
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p. 3285 - 3295
(2007/10/03)
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- Process for the synthesis of α-substituted acrylic acids and their application
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Process for the synthesis of a-substituted acrylic acids and their application. Process for the synthesis of a-substituted acrylic acids of general formula (I) and their application to the synthesis of N- (mercaptoacyl) aminoacid derivatives of formula (II). STR1
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- Electrochemical Cyclodimerization of Alkylidenemalonates
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Electrolysis of dimethyl alkylidenemalonates RCH=C(COOMe)2 (R=n-Alk, Ph) in an undivided cell in MeOH in the presence of alkali metal halide as mediator, leads to the formation of cyclic dimers, i.e., 3,4-disubstituted 1,1,2,2-cyclobutanetetracarboxylates.The reaction proceeds via the reductive coupling of two substrate molecules at cathode and the cyclization of a hydrodimer dianion by its interaction with an active form of a mediator, an anode-generated halogen.
- Elinson, Michail N.,Feducovich, Sergey K.,Zakharenkov, Alexandre A.,Ugrak, Bogdan I.,Nikishin, Gennady I.,et al.
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p. 5035 - 5046
(2007/10/02)
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- Photoaddition of ketene silyl acetals to electron-deficient arylakenes via single electron transfer
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Photoreaction of 1-cyano-2-phenylethene and 1,1-dicyano-2-phenylethene with β,β-dialkyl-substituted ketene silyl acetals in acetonitrile in the presence of aromatic hydrocarbon as a photosensitizer regioselectively afforded alkylated products in high yields.
- Mizuno, Kazuhiko,Takahashi, Naoki,Nishiyama, Toshinori,Inoue, Hiroo
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p. 7463 - 7466
(2007/10/02)
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- Stereoselective Epoxidation of Phe-Gly and Phe-Phe Vinyl Isosteres
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Novel Phe-Gly and Phe-Phe isosteres have been synthesized.Vinylic isosteres of Phe-Gly and Phe-Phe were prepared by facile Julia reactions, and the resulting stereoisomers were isolated and epoxidized (m-chloroperbenzoic acid).Observed stereoselectivities
- Jenmalm, Annika,Berts, Wei,Li, Yi-Lin,Luthman, Kristina,Csoeregh, Ingeborg,Hacksell, Uli
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p. 1139 - 1148
(2007/10/02)
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- Enzymatic Synthesis of Chiral Monosubstituted Malonates in Organic Solvents
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Prochiral stereospecificity of enzymes in organic solvents was used to develop a strategy for the formation of heretofore unknown chiral monosubstituted malonate diesters with high enantiomeric excess.The enzymatic reaction involved transesterification of symmetrical monosubstituted dimethyl malonates with benzyl alcohol, exploiting the ability of lipases to discriminate between the enantiotopic ester groups of the symmetrical malonate molecule.This enzymatic approach is not feasible in aqueous solutions because the activated malonic hydrogen invariably undergoes fast exchange accompanied by racemisation.The synthetic utility of this method was further demonstrated by converting the configurationally unstable mixed methyl benzyl diesters into the corresponding half esters, which were in turn selectively reduced into configurationally stable and synthetically useful hydroxyesters.
- Shapira, Michal,Gutman, Arie L.
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p. 1689 - 1700
(2007/10/02)
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- Photochemical carbon-silicon bond forming reaction on electron-deficient alkenes by disilanes and polysilanes via photoinduced electron transfer
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The phenanthrene-sensitized photoreaction of electron-deficient alkenes with disilanes in acetonitrile gave silylated alkanes in high yields.The photosilylation occurred in a highly regioselective manner at the position β to the electron-withdrawing group
- Mizuno, Kazuhiko,Nakanishi, Kazuhisa,Chosa, Jun-ichi,Otsuji, Yoshio
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- Electrochemical cyclodimerization of alkylidenemalonates into 3,4-disubstituted cyclobutane-1,1,2,2-tetracarboxylates
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Alkylidenemalonates being electrolyzed in methanol in undivided cell with glassy carbon, carbon or lead cathode in the presence of sodium iodide or sodium bromide are transformed into 3,4-disubstituted cyclobutane-1,1,2,2-tetracarboxylates.
- Nikishin, Gennady I.,Elinson, Michail N.,Feducovich, Sergey K.,Ugrak, Bogdan I.,Struchkov, Yuri T.,Lindeman, Sergey V.
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p. 3223 - 3226
(2007/10/02)
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- Arene Hydrides, 10. Michael Additions of Anthracene Hydride. Selective Reduction of the ArC=C Moiety by Fragmentation of the Michael Adduct
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Anthracene hydride (AH-) in THF undergoes Michael addition onto the acrylic acid derivatives 1 and 2.Secondary reactions of the first formed anions 3 and 4 of the Michael adducts depend on the absence (3) or presence (4) of an aryl group in β position.The non-benzylic 3 or its protonated or deprotonated form can cyclize via ester condensation to yield the "dibenzo-bicyclononanones" 10b,c.Deprotonation of the anion 4 by excess AH- usually leads to fragmentation of the C-CAr bond formed in the Michael addition.The overall result is a selective C=C reduction of cinnamonic acid derivatives and analogues: PhR'C=C -> PhR'CH-CH.This fragmentation is hampered in the Michael addition adduct 4h with dimethyl benzylidenemalonate 2h probably due to the necessity of a pronounced conformational reorganization during the fragmentation step.Key Words: Cinnamic acid derivatives, selective saturation / Michael addition / Anthracene hydride
- Sommer, Andreas,Stamm, Helmut
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- Electrochemical Hydroxylation, Methoxylation, and Hydroxymethylation of Active Methine Compounds
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Hydroxylation, methoxylation, or hydroxymethylation at the active methine group of phenylmalonate, benzylmalonate and diphenylacetate were achieved by anodic oxidation.
- Kawabata, Jin-ichi,Nozawa, Koohei,Kawai, Ken-ichi,Nakajima, Shoichi
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p. 181 - 183
(2007/10/02)
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- PHOTOSILYLATION OF ELECTRON-DEFICIENT ALKENES BY USE OF DISILANES VIA PHOTOINDUCED ELECTRON-TRANSFER
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The photosilylation on electron-deficient alkenes such as 1-aryl-2,2-dicyanoethenes occurred regioselectively at the β-position to the electron-withdrawing groups upon irradiation with disilanes and trisilane.
- Mizuno, Kazuhiko,Nakanishi, Kazuhisa,Chosa, Jun-ichi,Nguyen, Tien,Otsuji, Yoshio
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p. 3689 - 3692
(2007/10/02)
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- SYNTHESIS OF 4-SUBSTITUTED GLUTARIMIDES BY FREE RADICAL ADDITION OF IODOACETAMIDE TO α,β-UNSATURATED ESTERS
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Free radical addition of either methyl bromoacetate or iodoacetamide to an α,β-unsaturated ester gave the 4-substituted glutarate or glutarimide respectively, whereas the radical cyclisation of N-bromoacetyl crotonamide gave the 2-substituted succinimide.
- Sacripante, Guerino,Tan, Charles,Just, George
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p. 5643 - 5646
(2007/10/02)
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