- Iridium-catalyzed highly chemoselective and efficient reduction of nitroalkenes to nitroalkanes in water
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An iridium-catalyzed highly chemoselective and efficient transfer hydrogenation reduction of structurally diverse nitroalkenes was realized at very low catalyst loading (S/C = up to 10000 or 20?000), using formic acid or sodium formate as a traceless hydride donor in water. Excellent functionality tolerance is also observed. The turnover number and turnover frequency of the catalyst reach as high as 18?600 and 19?200 h-1, respectively. An inert atmosphere protection is not required. The reactivities of nitroalkenes are dependent on their substitution pattern, and the pH value is a key factor to accomplish the complete conversion and excellent chemoselectivity. Purification of products is achieved by simple extraction without column chromatography. The reduction procedure is facilely amplified to 10 g scale at 10?000 S/C ratio. The potential of this green reduction in enantioselective hydrogenation has been demonstrated.
- Chen, Yang,Liu, Changmeng,Xu, Dong,Xu, Jiaxi,Yang, Zhanhui
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supporting information
p. 6050 - 6058
(2021/08/23)
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- Method for high-selectivity reduction of nitroolefin C=C double bonds
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The invention provides a method for high-selectivity reduction of nitroolefin C=C double bonds. According to the method, a bidentate nitrogen ligand-[Cp* IrCl2] complex is used as the catalyst, nitroolefin can be conveniently converted into nitroalkane, the catalytic efficiency is extremely high, and the substrate conversion rate is 99% or above. The high-purity nitroalkane can be separated through simple extraction, liquid separation and solvent removal under reduced pressure. The selected solvent is water or a mixture of water and a hydrophilic solvent. The method is green, environment-friendly and high in reaction efficiency. The nitroalkane compound prepared by the invention is a very important organic intermediate, and has wide application in the fields of national defense, pesticide, biology, medicine, fine chemical engineering and the like.
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Paragraph 0053-0056
(2021/06/21)
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- Metal-Free Deoxygenation of Chiral Nitroalkanes: An Easy Entry to α-Substituted Enantiomerically Enriched Nitriles
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A metal-free, mild and chemodivergent transformation involving nitroalkanes has been developed. Under optimized reaction conditions, in the presence of trichlorosilane and a tertiary amine, aliphatic nitroalkanes were selectively converted into amines or nitriles. Furthermore, when chiral β-substituted nitro compounds were reacted, the stereochemical integrity of the stereocenter was maintained and α-functionalized nitriles were obtained with no loss of enantiomeric excess. The methodology was successfully applied to the synthesis of chiral β-cyano esters, α-aryl alkylnitriles, and TBS-protected cyanohydrins, including direct precursors of four active pharmaceutical ingredients (ibuprofen, tembamide, aegeline and denopamine).
- Pirola, Margherita,Faverio, Chiara,Orlandi, Manuel,Benaglia, Maurizio
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supporting information
p. 10247 - 10250
(2021/06/18)
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- A stable well-defined copper hydride cluster consolidated with hemilabile phosphines
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Copper hydrides are very useful in hydrogenation reactions. We report a stable Stryker-type copper hydride reagent protected by hemilabile phosphines: [Cu8H6(dppy)6](OTf)2(Cu8-H, dppy = diphenylphosphino-2-pyridine). The metal core of this cluster has a bicapped octahedral configuration, and the copper-bound hydrides each triply bridges over a triangular face of the octahedron. This cluster is attractive due to its facile preparation and excellent stability under ambient conditions. The comparable activity and selectivity both in the stoichiometric and catalytic reactions makeCu8-Ha promising alternative to Stryker's reagent.
- Yuan, Shang-Fu,Luyang, Heng-Wang,Lei, Zhen,Wan, Xian-Kai,Li, Jiao-Jiao,Wang, Quan-Ming
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p. 4315 - 4318
(2021/05/05)
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- Nitroalkene reduction in deep eutectic solvents promoted by BH3NH3
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Deep eutectic solvents (DESs) have gained attention as green and safe as well as economically and environmentally sustainable alternative to the traditional organic solvents. Here, we report the combination of an atom-economic, very convenient and inexpensive reagent, such as BH3NH3, with bio-based eutectic mixtures as biorenewable solvents in the synthesis of nitroalkanes, valuable precursors of amines. A variety of nitrostyrenes and alkyl-substituted nitroalkenes, including α- and β-substituted nitroolefins, were chemoselectively reduced to the nitroalkanes, with an atom economy-oriented, simple and convenient experimental procedure. A reliable and easily reproducible protocol to isolate the product without the use of any organic solvent was established, and the recyclability of the DES mixture was successfully investigated.
- Benaglia, Maurizio,Boselli, Monica Fiorenza,Faverio, Chiara,Gonzalez, Patricia Camarero,Puglisi, Alessandra
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supporting information
p. 1041 - 1047
(2021/05/17)
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- Expanding the Biocatalytic Toolbox with a New Type of ene/yne-Reductase from Cyclocybe aegerita
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This study introduces a new type of ene/yne-reductase from Cyclocybe aegerita with a broad substrate scope including aliphatic and aromatic alkenes/alkynes from which aliphatic C8-alkenones, C8-alkenals and aromatic nitroalkenes were the preferred substrates. By comparing alkenes and alkynes, a ~2-fold lower conversion towards alkynes was observed. Furthermore, it could be shown that the alkyne reduction proceeds via a slow reduction of the alkyne to the alkene followed by a rapid reduction to the corresponding alkane. An accumulation of the alkene was not observed. Moreover, a regioselective reduction of the double bond in α,β-position of α,β,γ,δ-unsaturated alkenals took place. This as well as the first biocatalytic reduction of different aliphatic and aromatic alkynes to alkanes underlines the novelty of this biocatalyst. Thus with this study on the new ene-reductase CaeEnR1, a promising substrate scope is disclosed that describes conceivably a broad occurrence of such reactions within the chemical landscape.
- Karrer, Dominik,Gand, Martin,Rühl, Martin
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p. 2191 - 2199
(2021/02/26)
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- Reduction of Activated Alkenes by PIII/PV Redox Cycling Catalysis
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The carbon–carbon double bond of unsaturated carbonyl compounds was readily reduced by using a phosphetane oxide catalyst in the presence of a simple organosilane as the terminal reductant and water as the hydrogen source. Quantitative hydrogenation was observed when 1.0 mol % of a methyl-substituted phosphetane oxide was employed as the catalyst. The procedure is highly selective towards activated double bonds, tolerating a variety of functional groups that are usually prone to reduction. In total, 25 alkenes and two alkynes were hydrogenated to the corresponding alkanes in excellent yields of up to 99 %. Notably, less active poly(methylhydrosiloxane) could also be utilized as the terminal reductant. Mechanistic investigations revealed the phosphane as the catalyst resting state and a protonation/deprotonation sequence as the crucial step in the catalytic cycle.
- Longwitz, Lars,Werner, Thomas
-
supporting information
p. 2760 - 2763
(2020/02/05)
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- METTL3 INHIBITORY COMPOUNDS
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The present invention relates to compounds of formula (I) that function as inhibitors of METTL3 (N6-adenosine-methyltransferase 70 kDa subunit) enzyme activity: X-Y-Z5 (I) wherein X, Y and Z are each as defined herein. The present invention also relates to processes for the preparation of these compounds, to pharmaceutical compositions comprising them, and to their use in the treatment of proliferative disorders, such as cancer, and autoimmune diseases, as well as other diseases or conditions in which METTL3 activity 10 is implicated.
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-
Paragraph 00290; 00573
(2020/10/20)
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- Celite-Polyaniline supported palladium catalyst for chemoselective hydrogenation reactions
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Polyaniline coated on particles of celite is used as support to load palladium catalyst. This heterogenized Celite?PANI?Pd system, is used as an efficient catalyst for chemoselective hydrogenation reactions. The catalyst is characterized by usual spectral, analytical techniques and studied for hydrogenation reactions at ambient conditions. The mild reaction conditions allow the control over the reactions and excellent selectivity is achieved in number of conversions. Hydrogenation of a carbon–carbon double bond was favored over other polar π-bond systems, while labile functional groups such as benzyl ether, benzyl esters, cyano, nitro and halogen remained unaffected. Primary amines were converted to N,N-dimethyl amines with formaldehyde, the double bond of coumarin was selectively hydrogenated without opening of the lactone functionality.
- Patel, Heta A.,Rawat, Maitreyee,Patel, Arun L.,Bedekar, Ashutosh V.
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- Substituted Pyrrolidine Amides II
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The invention relates to compounds according to general formula (I), which act as modulators of the glucocorticoid receptor and can be used in the treatment and/or prophylaxis of disorders which are at least partially mediated by the glucocorticoid receptor.
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- Dissipative Catalysis with a Molecular Machine
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We report on catalysis by a fuel-induced transient state of a synthetic molecular machine. A [2]rotaxane molecular shuttle containing secondary ammonium/amine and thiourea stations is converted between catalytically inactive and active states by pulses of a chemical fuel (trichloroacetic acid), which is itself decomposed by the machine and/or the presence of additional base. The ON-state of the rotaxane catalyzes the reduction of a nitrostyrene by transfer hydrogenation. By varying the amount of fuel added, the lifetime of the rotaxane ON-state can be regulated and temporal control of catalysis achieved. The system can be pulsed with chemical fuel several times in succession, with each pulse activating catalysis for a time period determined by the amount of fuel added. Dissipative catalysis by synthetic molecular machines has implications for the future design of networks that feature communication and signaling between the components.
- Biagini, Chiara,Fielden, Stephen D. P.,Leigh, David A.,Schaufelberger, Fredrik,Di Stefano, Stefano,Thomas, Dean
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supporting information
p. 9876 - 9880
(2019/07/04)
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- Reduction method of nitroolefin
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Relating to the technical field of organic synthesis, the invention particularly discloses a reduction method of nitroolefin. The method includes: adding a compound 1 into a mixed solvent of alcohol/water in a certain ratio, adding a metal borohydride at 0-50DEG C, and carrying out stirring reaction; concentrating the obtained solution to a constant weight, and adding ethyl acetate and a saturatedammonium chloride solution into the concentrate; separating the liquid to obtain an upper ethyl acetate layer, and conducting drying and concentrating to obtain a reduction product compound 2. The synthesis method provided by the invention is suitable for aromatic rings and straight-chain alkanes, can control dimer impurities at 3.0% or below and the HPLC purity of aliphatic or aromatic nitro compounds at 95.0% or above. The synthesis method provided by the invention has the advantages of cheap raw materials, green and environment-friendly process, economical efficiency and practicability, and is suitable for industrial production.
- -
-
Paragraph 0041-0043
(2019/12/11)
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- In Situ Generated Magnesium Cyanide as an Efficient Reagent for Nucleophilic Cyanation of Nitrosoalkenes and Parent Nitronates
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In situ generated magnesium cyanide [NaCN/Mg(ClO4)2] is suggested as a convenient, readily available, non-volatile and organic-soluble reagent for hydrocyanation reactions. It was successfully used for nucleophilic cyanation of nitrosoalkenes, nitronates, as well as other typical π-electrophiles, such as imines, α,β-unsaturated ketones, alkylidenemalonates and azoalkenes.
- Ushakov, Pavel Yu.,Tabolin, Andrey A.,Ioffe, Sema L.,Sukhorukov, Alexey Yu.
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p. 1888 - 1892
(2019/01/30)
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- Synthesis, antiproliferative and pro-apoptotic effects of nitrostyrenes and related compounds in Burkitt’s lymphoma
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Background: Cancers of the lymphatic cells (lymphomas) account for approximately 12% of malignant diseases worldwide. The nitrostyrene scaffold is identified as a lead target structure for the development of particularly effective compounds targeting Burkitt’s lymphoma (BL). Objectives: The aims of the curent study were to synthesise a panel of nitrostyrene compounds and to evaluate their activity in Burkitt’s lymphoma (BL). Methods: A panel of structurally varied compounds were designed and synthesised using Henry Knoevenagel condensation reactions. Single crystal X-Ray analysis confirmed the E configuration for six examples of these novel structures. A number of nitrostyrene-related compounds were also investigated including 1,3-bis(aryl)-2-nitropropenes together with heterocyclic scaffolds containing the nitrovinyl pharmacophore such as 3-nitro-2-phenyl-2H-chromenes. The antiproliferative activities of the compounds were evaluated using the BL cell lines EBV- MUTU-1 and EBV+ DG-75 (chemoresistant) to establish preliminary structure-activity relationships. Results: Lead compounds with optimized nitrostyrene scaffolds and 3-nitro-2-phenyl-2Hchromene structures were successfully established with typical IC50 values of 0.45 μM and 0.47 μM in MUTU-1 cells and 1.41 μM and 1.92 μM, respectively, in DG-75 cells. The mechanism of cell death was identified as apoptotic and the lead compound was found to elicit comparable apoptotic effects to Taxol in Burkitt’s lymphoma cell lines MUTU-1 and DG-75. Conclusion: This class of pharmaceutically active compounds with potential for the treatment of Burkitt’s lymphoma suggest a potential role for nitrostyrene based agents in chemotherapy.
- Byrne, Andrew J.,Bright, Sandra A.,Fayne, Darren,McKeown, James P.,McCabe, Thomas,Twamley, Brendan,Williams, Clive,Meegan, Mary J.
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p. 181 - 199
(2018/03/13)
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- Enantioselective Conjugate Additions of 2-Alkoxycarbonyl-3(2 H)-furanones
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Enantioselective conjugate additions of in situ generated 2-alkoxycarbonyl-3(2H)-furanones to three distinct types of π-electrophiles (terminal alkynones, α-bromo enones, and α-benzyl nitroalkenes) are reported. Catalysis by a nickel(II)-diamine complex provided alkynone-derived adducts with high enantioselectivity, preferentially as the Z-isomers, and completely suppressed the undesired O-alkylation pathway. A cupreidine-based catalyst enabled extension of the enantioselective conjugate additions to α-bromo enones and α-benzyl nitroalkenes. The densely functionalized adducts that result are useful precursors to synthetic analogs of spirocyclic natural products pseurotins.
- Vojá?ková, Petra,Chalupa, David,Prieboj, Jozef,Ne?as, Marek,?venda, Jakub
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supporting information
p. 7085 - 7089
(2018/11/23)
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- 1, 3-diphenyl-1-propanol and method for synthesizing 1, 3-diphenyl-1-propanol from nitromethane
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The invention discloses 1, 3-diphenyl-1-propanol and a method for synthesizing the 1, 3-diphenyl-1-propanol from nitromethane, and belongs to the technical field of chemical synthesis. The method forsynthesizing the 1, 3-diphenyl-1-propanol from the nitromethane, provided by the invention, comprises the following steps: performing a reaction on the nitromethane and benzaldehyde in an alkaline environment under the action of sodium borohydride to obtain 2-phenylnitroethane; performing a reaction on the 2-phenylnitroethane and the benzaldehyde under the actions of an L-valine derivative and anadditive to obtain 2-nitro-1, 3-diphenylpropanol; and performing a reaction on the 2-nitro-1, 3-diphenylpropanol under the actions of tributyl tin hydride and azobisisobutyronitrile to remove nitro toobtain the 1, 3-diphenyl-1-propanol. The preparation method is simple in operation and low in cost; and by the preparation method, a product with the required optical purity can be prepared. In addition, the invention further relates to the 1, 3-diphenyl-1-propanol prepared by the preparation method.
- -
-
Paragraph 0065; 0069-0071; 0075-0077
(2018/07/06)
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- Mechanistic Investigations of Reactions of the Frustrated Lewis Pairs (Triarylphosphines/B(C6F5)3) with Michael Acceptors
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Frustrated Lewis pair (FLP)-catalyzed reduction of Michael acceptors is a challenging reaction that proceeds with specific FLP structures. Kinetics and equilibrium of the reactions of two phosphines (Ar3P), namely tri(1-naphthyl)phosphine and tri(o-tolyl)phosphine, are reported with reference electrophiles. The reason for the failure of the FLPs (Ar3P/B(C6F5)3) to reduce activated alkenes under H2 pressure is shown to be a hydrophosphination process that inhibits the reduction reaction. Kinetic and thermodynamic factors controlling both pathways are discussed in light of Mayr's free linear energy relationships.
- Dupré, Jonathan,Gaumont, Annie-Claude,Lakhdar, Sami
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supporting information
p. 694 - 697
(2017/02/10)
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- New insights into the catalytic reduction of aliphatic nitro compounds with hypophosphites under ultrasonic irradiation
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This work describes an efficient process for the reduction of nitro compounds to the corresponding amines with a catalytic amount of Pd/C (0.6 mol%), and a mixture of sodium hypophosphite and hypophosphorous acid as a reducing agent in H2O/2-MeTHF at 60 °C. The reaction was optimized under silent conditions. The conditions for the in situ production of H2 using the mixture NaH2PO2/H3PO2 were studied. The influence of ultrasonic activation was investigated both in terms of efficiency and kinetics. The reaction was shown to be efficient in water, at 70 °C with a quantitative conversion and a maximal yield in only 15 min thanks to the ultrasonic activation. Finally, ultrasound was proved to act as a physical agent of phase transfer.
- Letort,Lejeune,Kardos,Métay,Popowycz,Lemaire,Draye
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supporting information
p. 4583 - 4590
(2017/10/13)
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- Nano-NiFe2O4 as an efficient catalyst for regio- and chemoselective transfer hydrogenation of olefins/alkynes and dehydrogenation of alcohols under Pd-/Ru-free conditions
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Here, we have demonstrated the magnetic nano-NiFe2O4 catalyzed transfer hydrogenation of olefins/alkynes using isopropyl alcohol as a source of hydrogen under ligand/base/Pd-/Ru-metal-free conditions, and dehydrogenation of alcohols under oxidant-free conditions.
- Payra, Soumen,Saha, Arijit,Banerjee, Subhash
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p. 52495 - 52499
(2016/06/13)
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- Iridium(I) N-Heterocyclic Carbene (NHC)/Phosphine Catalysts for Mild and Chemoselective Hydrogenation Processes
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The directed chemoselective hydrogenation of olefins has been established by using iridium(I) catalysts, which feature a tuned NHC/phosphine ligand combination. This selective reduction process has been demonstrated in a wide array of solvents, including more environmentally acceptable media, also allowing further refinement of hydrogenation selectivity. The directed, chemoselective hydrogenation of olefins has been established by using iridium(I) catalysts, which feature a tuned NHC/phosphine ligand combination. This selective reduction process has been demonstrated in a wide array of solvents, including more environmentally acceptable media, also allowing further refinement of hydrogenation selectivity.
- Kerr, William J.,Mudd, Richard J.,Brown, Jack A.
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supporting information
p. 4738 - 4742
(2016/04/05)
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- Conversion of nitroalkanes into carboxylic acids via iodide catalysis in water
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We report a new method for the conversion of nitroalkanes into carboxylic acids that achieves this transformation under very mild conditions. Catalytic amounts of iodide in combination with a simple zinc catalyst are needed to give good conversions into the corresponding carboxylic acids.
- Marcé, Patricia,Lynch, James,Blacker, A. John,Williams, Jonathan M. J.
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p. 1013 - 1016
(2016/01/16)
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- Construction of chiral 2-substituted octahydroindoles from cyclic ketones and nitroolefins bearing only one α-substituent
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A dual catalytic system has been developed following the screening of a series of chiral primary amine catalysts and chiral phosphoric acid catalysts for the Michael addition of cyclic ketones to nitroolefins bearing only one α-substituent. The resulting γ-nitro ketones, which contain a substituent on the carbon connected to the nitro group, were formed in excellent yields (>80%) with high levels of stereoselectivity (up to 94:6 dr and 98% ee) when the reaction was performed in benzene at 0 °C with 10 mol% of the optimal amine/phosphoric acid combination (1:1) as a catalyst. Subsequent reduction of the nitro group followed by intramolecular reductive amination could afford optically active cis-octahydroindole analogues bearing a non-functional substituent at their 2-position.
- Han, Yong,Zheng, Bo,Peng, Yungui
-
supporting information
p. 1136 - 1142
(2015/04/22)
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- Organocatalytic enantioselective formal C(sp2)-H alkylation
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An organocatalytic enantioselective formal C(sp2)-H alkylation is reported. This alkylative desymmetrization of prochiral 2,2-disubstituted cyclopentene-1,3-dione is catalyzed by a bifunctional tertiary aminourea derivative, utilizes air-stable and inexpensive nitroalkanes as the alkylating agents, and delivers synthetically versatile five-membered carbocycles containing an all-carbon quaternary stereogenic center remote from the reaction site in excellent enantioselectivity.
- Manna, Madhu Sudan,Mukherjee, Santanu
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supporting information
p. 130 - 133
(2015/01/30)
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- Catalytic Asymmetric Synthesis of Isoxazolines from Silyl Nitronates
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1,3-Dipolar cycloadditions of triisopropylsilyl nitronates and 2-alkylacroleins produced isoxazolines bearing a chiral quaternary center in high yields and enantioselectivities with the aid of a chiral oxazaborolidine catalyst. One chiral isoxazoline product was converted to (R)-(+)-Tanikolide in 9 steps in a total yield of 43%. (Chemical Equation Presented).
- Han, Xiaoyu,Dong, Li,Geng, Caiwei,Jiao, Peng
-
supporting information
p. 3194 - 3197
(2015/07/15)
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- Copper(II)-catalyzed oxidative N-nitrosation of secondary and tertiary amines with nitromethane under an oxygen atmosphere
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The combination of a catalytic amount of Cu(OTf)2 and less than a stoichiometric amount of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) under an O2 atmosphere effectively promoted the N-nitrosation of both secondary aromatic/aliphatic amines and tertiary aromatic amines with nitromethane (CH3NO2) leading to the preparation of N-nitrosamine derivatives.
- Sakai, Norio,Sasaki, Minoru,Ogiwara, Yohei
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p. 11638 - 11641
(2015/07/15)
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- A novel transition metal free [bis-(trifluoroacetoxy)iodo]benzene (PIFA) mediated oxidative ipso nitration of organoboronic acids
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A mild, convenient and transition metal free methodology for oxidative ipso nitration of diversely functionalized organoboronic acids, including heteroaryl- and alkylboronic acids, has been developed at ambient temperature using a combination of [bis-(trifluoroacetoxy)]iodobenzene (PIFA) - N-bromosuccinimide (NBS) and sodium nitrite as the nitro source. It is anticipated that the reaction proceeds through in situ generation of NO2 and O-centred organoboronic acid radicals followed by the formation of an O-N bond via combination of the said radicals. Finally transfer of the NO2 group to the aryl moiety occurs through 1,3-aryl migration to provide the nitroarenes.
- Chatterjee, Nachiketa,Bhatt, Divya,Goswami, Avijit
-
supporting information
p. 4828 - 4832
(2015/05/05)
-
- Resin-trapped gold nanoparticles: An efficient catalyst for reduction of nitro compounds and Suzuki-Miyaura coupling
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Gold in nanoparticle form shows good catalytic activity in contrast to bulk form and is finding applications in a variety of organic reactions. The present investigation describes direct deposition of gold nanoparticles onto commercially available resin by sorption reduction method. Uniformly dispersed nanoparticles of 3-8 nm dimensions were characterized by UV-visible spectroscopy, XRD, SEM and TEM, etc. The AuNPs were found to be remarkably stable and active catalysts for the selective reduction of nitro group under mild reaction conditions and microwave-assisted ligand-free Suzuki-Miyaura cross-coupling reaction between aryl halides and phenylboronic acid. Calculated rate constant (2.5 × 10-2 s-1) for the reduction of 4-nitrophenol is among the best reported in the literature. The versatility of both the protocols is demonstrated by taking a number of substrates.
- Shah, Dipen,Kaur, Harjinder
-
-
- Immobilization of palladium catalyst on magnetically separable polyurea nanosupport
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This work describes a method for preparing magnetic polyurea nanoparticles (PU NPs) and their utilization as a catalyst support. The method is based on entrapment of hydrophilic magnetic nanoparticles within the polyurea matrix. The synthetic process of these magnetic polyurea nanoparticles is based on oil-in-oil nanoemulsification of an organic polar phase comprised of N,N-dimethylacetamide (DMAc), 2,6-diaminopyridine and ionic liquid modified magnetite nanoparticles (MNPs-IL), in heptane containing a suitable surfactant. This was followed by interfacial polycondensation reaction between an isocyanate monomer, polymethylenepolyphenyl isocyanate (PAPI 27), and the amine monomer producing magnetically separable polyurea nanoparticles. Subsequently, these particles were employed as a catalyst nanosupport. Two catalytic systems based on the encapsulation of Pd(OAc)2 within magnetic PU NPs or their adsorption on the surface of these particles were produced and subjected to hydrogenation reactions and selective hydrogenations of α,β-unsaturated compounds. Pd(OAc)2 adsorbed on the surface of the magnetic PU NPs demonstrated high catalytic activity and selectivity, which was superior to the conventional catalyst Pd/C or palladium nanoparticles supported directly on the surface of magnetite nanoparticles. The catalyst was easily recovered from the reaction mixture by applying an external magnetic field and recycled over five times without observing any significant loss in its catalytic efficiency. This journal is
- Natour, Suzana,Abu-Reziq, Raed
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p. 48299 - 48309
(2014/12/10)
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- Useful extensions of the henry reaction: Expeditious routes to nitroalkanes and nitroalkenes in aqueous media
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The products of the Henry nitroaldol reaction from nitromethane and several aldehydes were reduced to the corresponding nitroalkanes with (n-Bu) 3SnH in water under microwave irradiation (80 °C/10 min), or dehydrated to the corresponding nitroalkenes with K2CO3 in water (generally 0-5 °C/20 min). Both "one-pot" reactions occur in excellent yields across a range of aliphatic and aromatic (including heteroaromatic) substrates. It seems likely that the deoxygenation of the nitroaldols occurs via coordination of an oxygen atom of the nitro group with a tin atom, which facilitates hydride delivery in the transition state. The elimination of water from the nitroaldols in mild base is likely driven by the stability of the conjugated nitroalkene products. The elimination required workup with 2 N HCl, which likely displaces a nitroalkane-nitroalkene equilibrium towards the latter. These extensions of the Henry reaction lead to products not easily obtained otherwise.
- Chandrasekhar, Sosale,Shrinidhi, Annadka
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p. 3008 - 3018
(2014/10/16)
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- Catalyst-free chemoselective reduction of the carbon-carbon double bond in conjugated alkenes with Hantzsch esters in water
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A simple, efficient and green protocol for chemoselective reduction of carbon-carbon double bond in conjugated alkenes with Hantzsch esters is described. Without any additional catalysts, a series of conjugated alkenes with strong electron-withdrawing groups were reduced in water with excellent yield. Functional groups such as nitrile, ester, nitro, fluoro, chloro, bromo, furanyl and benzyl are all tolerated by the reaction conditions employed. The Royal Society of Chemistry.
- He, Qi,Xu, Zhihong,Jiang, Dehong,Ai, Wensi,Shi, Ronghua,Qian, Shan,Wang, Zhouyu
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p. 8671 - 8674
(2014/03/21)
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- Iridium(I)-catalyzed regioselective C-H activation and hydrogen-isotope exchange of non-aromatic unsaturated functionality
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Isotopic labelling is a key technology of increasing importance for the investigation of new C-H activation and functionalization techniques, as well as in the construction of labelled molecules for use within both organic synthesis and drug discovery. Herein, we report for the first time selective iridium-catalyzed C-H activation and hydrogen-isotope exchange at the β-position of unsaturated organic compounds. The use of our highly active [Ir(cod)(IMes)(PPh3)][PF6] (cod = 1, 5-cyclooctadiene) catalyst, under mild reaction conditions, allows the regioselective β-activation and labelling of a range of α, β-unsaturated compounds with differing steric and electronic properties. This new process delivers high levels of isotope incorporation over short reaction times by using low levels of catalyst loading.
- Kerr, William J.,Mudd, Richard J.,Paterson, Laura C.,Brown, Jack A.
-
supporting information
p. 14604 - 14607
(2015/03/04)
-
- Unusual reactivity of nitronates with an aryl alkyl carbonate: Synthesis of α-amino esters
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The monoanions of nitroalkanes are ambident nucleophiles that react with carbonate electrophiles through the oxygen atom. Products arising from reactivity at the carbon atom will yield α-nitro esters, which are precursors for α-amino esters. We demonstrate this in the reactions of nitroalkanes with benzyl phenyl carbonate and DABCO where α-nitro esters are obtained instead of nitrile oxides. The products are readily reduced to α-amino esters. This pathway could be a safe alternative to the Strecker reaction.
- Reddy, Golipalli Ramana,Mukherjee, Debopreeti,Chittoory, Arjun Kumar,Rajaram, Sridhar
-
supporting information
p. 5874 - 5877
(2015/01/08)
-
- A novel method to access chiral nonnatural 2,4-disubstituted pyrrolidines from aldehydes and nitroolefins only with an α-substituent
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A series of α-substituted nitroolefins were employed in organocatalytic asymmetric Michael reactions with aldehydes. γ-Nitro carbonyl products were achieved in good yields (up to 86%) with good stereoselectivities (up to 96% ee and 24 : 1 dr). Reduction of the nitro group followed by intramolecular reductive amination successfully afforded various novel optically active 2,4-disubstituted pyrrolidine compounds.
- Zheng, Bo,Wang, Hui,Han, Yong,Liu, Changlu,Peng, Yungui
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supporting information
p. 4561 - 4563
(2013/06/04)
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- Tuning the lewis acidity of boranes in frustrated lewis pair chemistry: Implications for the hydrogenation of electron-poor alkenes
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An analysis of the metal-free reduction of electron deficient olefins by frustrated Lewis pairs indicates that the rate-determining step might be either the heterolytic cleavage of H2 to form an -onium borohydride salt, or the subsequent transfer of the hydride moiety to the substrate following a Michael-type addition reaction. While the use of strong Lewis acids such as B(C6F5)3 facilitates the first of these processes, hydride transfer to the olefin should be contrarily favoured by the use of weak Lewis acids which, for this very same reason, might be unable to promote the prior H2 split. After systematic testing of several boranes of different Lewis acidity (assessed by using the Childs' method) and steric demand, an optimal situation that employs tris(2,4,6-trifluorophenyl) borane was reached. Mixtures of this borane with 1,4-diazabicyclo[2.2.2]octane (DABCO) exhibited excellent catalytic activity for the hydrogenation of alkylidene malonates. In fact, this transformation could be achieved under milder conditions than those we reported previously. Moreover, the reaction scope could be expanded to other electron deficient olefins containing esters, sulfones or nitro functionalities as electron-withdrawing substituents.
- Nicasio, Juan A.,Steinberg, Sebastian,Ines, Blanca,Alcarazo, Manuel
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p. 11016 - 11020
(2013/09/02)
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- Functional-group tolerance in frustrated lewis pairs: hydrogenation of nitroolefins and acrylates
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Weak Lewis acid for high nucleophilicity: Hydridoborate derived from B(2,6-F2C6H3)3 shows significant hydride character. Solid-state and solution structure analysis revealed a dihydrogen-bonded aggregate. The new frustrated Lewis pair was applied in the hydrogenation of nitroolefins and acrylates (see scheme; EWG=electron- withdrawing group). The decreased Lewis acidity provides higher reactivity and functional-group tolerance. Copyright
- Greb, Lutz,Daniliuc, Constantin-Gabriel,Bergander, Klaus,Paradies, Jan
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supporting information
p. 5876 - 5879
(2013/07/05)
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- Reactions of nitric oxide and nitrogen dioxide with coenzyme Q: Involvement of the isoprenic chain
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The formation of a di-tert-alkyl nitroxide has been observed by Electron Spin Resonance during the exposure of coenzyme CoQ10, in both the oxidized and reduced forms, to nitrogen dioxide (NO2) or to nitric oxide (NO) in the presence of oxygen. The same kind of nitroxide has been observed also with CoQ1, CoQ3 or with 1-phenyl-3-methyl-2- butene, chosen as model compounds. In all cases, the formation of the nitroxide may be justified only by admitting the involvement of the isoprenic chain of the coenzymes and in particular the addition of NO2 to the double bond. A mechanism which accounts for the formation of the nitroxide as well as the other compounds observed in the reactions is proposed and confirmed by a spectroscopic investigation (FT-IR, 1H NMR, X-ray analysis) and by ESI-MS.
- Astolfi, Paola,Charles, Laurence,Gigmes, Didier,Greci, Lucedio,Rizzoli, Corrado,Sorana, Federico,Stipa, Pierluigi
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supporting information
p. 1399 - 1406
(2013/05/21)
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- Synthesis and anti-inflammatory activity of aromatic glucosinolates
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Aromatic GLs are important members of the glucosinolate family of compounds because of their potential biological activity and medicinal properties. This study has shown success in the high yielding synthesis of some important aromatic GLs as well as the results of testing for anti-inflammatory properties of the synthetic GLs. 3,4-Dimethoxyphenylglucosinolate was found to be the most active anti-inflammatory of the seven glucosinolates assayed.
- Vo, Quan V.,Trenerry, Craige,Rochfort, Simone,Wadeson, Jenny,Leyton, Carolina,Hughes, Andrew B.
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p. 5945 - 5954
(2013/09/23)
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- New approach to oximes through reduction of nitro compounds enabled by visible light photoredox catalysis
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A range of nitro compounds are smoothly reduced to their corresponding oximes under the synergistic effects of visible light irradiation, the Ru(bpy)3Cl2 photocatalyst, Hünig's base, Mg(ClO 4)2 activation, and MeCN solvent. This remarkably mild and environmentally benign protocol, when orchestrated with classical Beckmann rearrangement, enables such high-value industrial feedstock as caprolactam to be readily accessed from simple precursor nitrocyclohexane.
- Cai, Shunyou,Zhang, Shaolong,Zhao, Yaohong,Wang, David Zhigang
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supporting information
p. 2660 - 2663
(2013/07/11)
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- The highly chemoselective transfer hydrogenation of the carbon-carbon double bond of conjugated nitroalkenes by a rhodium complex
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Chemoselective transfer hydrogenation of conjugated nitroalkenes catalyzed by [RhCl2Cp·]2-diamine complex (Cp ·=η5-C5Me5) using HCOOH/Et3N (5:2) (TEAF) as a hydrogen source was realized. A variety of nitrostyrenes, β-methyl nitrostyrenes, and 3-methyl-4-nitro-5-alkenyl- isoxazoles were reduced smoothly in good to excellent yields in short reaction time. Other functional groups are inert under the reaction conditions.
- Xiang, Jing,Sun, Er-Xiao,Lian, Chun-Xia,Yuan, Wei-Cheng,Zhu, Jin,Wang, Qiwei,Deng, Jingen
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experimental part
p. 4609 - 4620
(2012/07/28)
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- S-benzyl isothiouronium chloride as a recoverable organocatalyst for the reduction of conjugated nitroalkenes with Hantzsch ester
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The reduction of conjugated nitroalkenes into nitroalkanes with Hantzsch ester using S-benzyl isothiouronium chloride as a recoverable organocatalyst was successfully accomplished with high yield and excellent chemoselectivity.
- Nguyen, Quynh Pham Bao,Kim, Jae Nyoung,Kim, Taek Hyeon
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supporting information; experimental part
p. 6513 - 6516
(2012/08/28)
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- Visible-light-promoted C-C bond cleavage: Photocatalytic generation of iminium ions and amino radicals
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Photoscissors: Structurally variable and synthetically robust iminium ions and amino radicals species could be simultaneously generated by visible-light-promoted photoredox cleavage of the C-C bonds in simple vicinal diamine precursors under very mild reaction conditions. Copyright
- Cai, Shunyou,Zhao, Xinyang,Wang, Xinbo,Liu, Qisong,Li, Zigang,Wang, David Zhigang
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supporting information; experimental part
p. 8050 - 8053
(2012/08/29)
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- Henry reaction of fluorinated nitro compounds
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The Henry (nitroaldol) reaction of fluorinated nitro compounds with various aromatic aldehydes and a fluorinated aliphatic aldehyde to give β-fluoro-β-nitroalcohols which bearing a fluorinated quaternary carbon center was reported. The relative configuration of the major diastereoisomer of 2-fluoro-2-nitro-1-(4-nitrophenyl)-3-phenylpropanol (5bf) was determined by X-ray single crystal analysis.
- Hu, Huawei,Huang, Yangen,Guo, Yong
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experimental part
p. 108 - 114
(2012/02/05)
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- Selective hydrogenation of nitroarenes and olefins over rhodium nanoparticles on hydroxyapatite
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We have demonstrated a highly active and selective nanocatalyst, Rh/HAP (rhodium supported on hydroxyapatite), for the reduction of nitroarenes with hydrazine and for the hydrogenation of olefins with hydrogen gas under mild conditions. Nitroarenes were hydrogenated selectively to the corresponding anilines over the Rh/HAP catalyst with hydrazine as reducing agent, and reducible groups, such as halides (fluorine, chlorine, bromine and iodine), cyano and alkene were untouched. Moreover, olefins can be hydrogenated selectively to the corresponding alkanes in good yields over the Rh/HAP catalyst in the presence of reducible nitro, carbonyl and cyano groups when H 2 was used.
- Huang, Lei,Luo, Pingfei,Pei, Weige,Liu, Xiaoyun,Wang, Yong,Wang, Jun,Xing, Weihong,Huang, Jun
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p. 2689 - 2694
(2013/01/15)
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- Benzylation of nitroalkanes using copper-catalyzed thermal redox catalysis: Toward the facile C-alkylation of nitroalkanes
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The C-alkylation of nitroalkanes under mild conditions has been a significant challenge in organic synthesis for more than a century. Herein we report a simple Cu(I) catalyst, generated in situ, that is highly effective for C-benzylation of nitroalkanes using abundant benzyl bromides and related heteroaromatic compounds. This process, which we believe proceeds via a thermal redox mechanism, allows access to a variety of complex nitroalkanes under mild reaction conditions and represents the first step toward the development of a general catalytic system for the alkylation of nitroalkanes.
- Gildner, Peter G.,Gietter, Amber A. S.,Cui, Di,Watson, Donald A.
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supporting information; experimental part
p. 9942 - 9945
(2012/08/07)
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- Palladium-supported ionic liquid catalyst (Pd-SH-SILC) immobilized on mercaptopropyl silica gel as a chemoselective, reusable and heterogeneous catalyst for catalytic hydrogenation
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Palladium acetate was immobilized as Pd-SH-SILC (Pd-supported ionic liquid catalyst) in the pores of amorphous mercaptopropyl silica gel with the aid of an ionic liquid [bmim]BF4. The heterogeneous Pd-SH-SILC was effective for catalytic hydrogenation of a variety of olefins at atmospheric pressure and room temperature. It withstood recycling up to 10 times by decantation.
- Hagiwara, Hisahiro,Nakamura, Tomomi,Hoshi, Takashi,Suzuki, Toshio
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scheme or table
p. 1133 - 1137
(2011/06/26)
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- Control of chemoselectivity in hydrogenations of substituted nitro- and cyano-aromatics by cluster-derived ruthenium nanocatalysts
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Catalyst precursors 1 and 2, made by ion-pairing [H3Ru 4(CO)12]- with NR4+ groups of functionalized MCM-41 and water-soluble poly(diallyldimethylammonium chloride), PDADMAC, respectively, have been evaluated for the chemoselective hydrogenation of nitro- and cyano-benzaldehydes. They are found to be inert toward -NO2 and -CN groups, but active for the reduction of -CHO and >C=C4 (3) or with (5%)Ru-Al2O3, where both the functional groups are hydrogenated. Kinetic analyses have been carried out for the hydrogenation of 4-nitrobenzaldehyde with 2. Existence of an induction time and two competitive equilibriums followed by the product-forming rate-determining step are inferred from the empirically derived rate expression. The kinetic results, structural evidences, and previous work strongly suggest that the observed chemoselectivity is probably a result of the absence of multiple crystal planes, differing in Miller indices, in the cluster-derived catalysts.
- Indra, Arindam,Maity, Niladri,Maity, Prasenjit,Bhaduri, Sumit,Lahiri, Goutam Kumar
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experimental part
p. 176 - 183
(2012/02/02)
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- Cascade formation of isoxazoles: Facile base-mediated rearrangement of substituted oxetanes
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Give me five! Nitro compounds and oxetan-3-one react through an intriguing cascade sequence to give isoxazole-4-carbaldehydes using inexpensive reagents in a one-pot procedure (see scheme; Ms=methanesulfonyl). A variety of 3-substituted isoxazole-4-carbaldehydes were obtained in high overall yields.
- Burkhard, Johannes A.,Tchitchanov, Boris H.,Carreira, Erick M.
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p. 5379 - 5382
(2011/07/08)
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- Catalyst-free and solventless Hantzsch ester mediated reduction of nitroolefins at elevated temperature
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A catalyst-free and solventless protocol for the reduction of nitroolefins to the corresponding nitroalkanes at 100°C has been developed. Various nitroalkenes have been reduced in good to excellent yield with short reaction times.
- Chauhan, Pankaj,Kaur, Kirandeep,Bala, Neeraj,Kumar, Vikas,Chimni, Swapandeep Singh
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experimental part
p. 304 - 309
(2011/05/02)
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- Autocatalysis and organocatalysis with kemp's triacid compounds
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Synthetic structures capable of autocatalysis based on molecular recognition - self-replication - were introduced nearly 20 years ago. These systems involved neither informational oligomers such as nucleic acids nor conditions that are generally regarded as prebiotic, but they revealed how self-complementary molecules could act as templates for their own formation and helped define the structure of minimalist replicators. Recent expansions in the field of organocatalysis raise the possibility that a synthetic structure might behave as an autocatalyst and function as a chemical catalyst for other reactions. We show here that these properties can be engineered into a single synthetic structure: the compound can selectively accelerate its own formation and catalyzes hydrogenation reactions of nitrostyrene. It is likely that a wide variety of synthetic structures can be modified for autocatalysis and organocatalysis. The Japan Institute of Heterocyclic Chemistry.
- Ajami, Dariush,Kamioka, Seiji,Sather, Aaron C.,Hooley, Richard J.,Rebek Jr., Julius
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scheme or table
p. 1203 - 1215
(2011/05/14)
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- Alternative method for the reduction of aromatic nitro to amine using TMDS-iron catalyst system
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The system 1,1,3,3-tetramethyldisiloxane (TMDS)/Fe(acac)3 is reported here as a new method to obtain amines from aromatic nitro compounds. Amines are synthetized in a straightforward step and are isolated as hydrochloride salts with good to excellent yields. This system has shown a good selectivity toward aryl-chloride, aryl-bromide, ester, carboxylic acid, and cyano groups. The reduction of alkylnitro compounds was unfortunately not possible using this method, only a mixture of mono and dialkylated amine was obtained.
- Pehlivan, Leyla,Métay, Estelle,Laval, Stéphane,Dayoub, Wissam,Demonchaux, Patrice,Mignani, Gérard,Lemaire, Marc
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body text
p. 1971 - 1976
(2011/04/22)
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