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Background The side reactions of dehalogenation or C–N coupling tend to occur when halogenated aromatic amines are prepared by catalytic hydrogenation reduction of halogenated aromatic nitro compounds. In this paper, we prepared the sub-microspherical Fe3O4@PDA-Pd NPs catalyst apply it efficiently in the hydrogenation reduction of halogenated aromatic nitro compounds to prepare the halogenated aromatic amines under atmospheric pressure. The catalyst shows a high selectivity of greater than 96% and can effectively inhibit the occurrence of the side reactions of dehalogenation and C–N coupling. Results The optimum condition of the hydroreduction reaction is when tetrahydrofuran is used as solvent and the reaction happens at 50 °C for 5 h. The selectivity of the chlorinated aromatic amine and the fluorinated aromatic amine products exceed 99% and the yield exceeds 90%. Only a small amount of dehalogenated products and C–N coupling by-products were produced in the brominated aromatic compound and the iodinated aromatic compound. Conclusion We developed a promising method for preparing the superparamagnetic and strongly magnetic Fe3O4@PDA core–shell sub-microsphere-supported nano-palladium catalyst for catalyzing the hydrogenation reduction of halogenated aromatic nitro compounds. The halogenated aromatic amines were efficiently and highly selectively prepared under atmospheric pressure, with the side reactions of dehalogenation and C–N coupling effectively inhabited simultaneously.

In this paper, a new plasma spray technology working in low pressure condition has been successfully applied to deposit Lix(Ni,Co)yO2 catalyst/electrode layers for low-temperature solid oxide fuel cells (LT-SOFCs). The low pressure induced distinctive phenomena were illustrated for presenting the characteristics and advances of such coating technique. Micro-nano crystalline microstructure was generated on the plasma sprayed coatings simultaneously with phase transformation taking place. To study the effect of high temperature on such catalyst material, sintering experiments were carried out at 600–1000 °C. The results show that the ratio of x/y decreased when increasing temperature and sintering time because of the degradation of Li from Lix(Ni,Co)yO2 phase. The catalytic property and stability of the Lix(Ni,Co)yO2 at various temperatures were also discussed.

Large-size, superparamagnetic, and highly magnetic Fe3O4@PDA core−shell submicrosphere-supported nano-palladium catalysts were prepared in this study. Dopamine was encapsulated on the surface of Fe3O4 particles via self-polymerization and then protonated to positively charge the microspheres. PdCl42− was dispersed on the surface of the microspheres by positive and negative charge attraction and then reduced to nano-palladium. With air as oxidant, the catalyst can successfully catalyze the dehydrogenation of benzyl alcohols to produce the corresponding aldehydes at 120 °C.

Schwann cells (SCs) are a highly plastic cell type capable of undergoing phenotypic changes following injury or disease. SCs are able to upregulate genes associated with nerve regeneration and ultimately achieve functional recovery. During the regeneration process, the extracellular matrix (ECM) and cell morphology play a cooperative, critical role in regulating SCs, and therefore highly impact nerve regeneration outcomes. However, the roles of the ECM and mechanotransduction relating to SC phenotype are largely unknown. Here, we describe the role that matrix stiffness and cell morphology play in SC phenotype specification via known mechanotransducers YAP/TAZ and RhoA. Using engineered microenvironments to precisely control ECM stiffness, cell shape, and cell spreading, we show that ECM stiffness and SC spreading downregulated SC regenerative associated proteins by the activation of RhoA and YAP/TAZ. Additionally, cell elongation promoted a distinct SC regenerative capacity by the upregulation of Rac1/MKK7/JNK, both necessary for the ECM and morphology changes found during nerve regeneration. These results confirm the role of ECM signaling in peripheral nerve regeneration as well as provide insight to the design of future biomaterials and cellular therapies for peripheral nerve regeneration.

A novel method is developed for the enantioselective synthesis of highly functionalized 3,4-disubstituted dihydro-2(1H)-quinolinones bearing two trans contiguous stereogenic centers with excellent diastereoselectivities (up to >99 : 1 dr) and high to excellent enantioselectivities (up to >99% ee). The process combines an enantioselective organocatalytic Michael–hemiaminalization reaction and a highly efficient oxidation reaction sequence with good yields and stereoselectivity.

An organocatalytic Michael reaction of cycloheptanone and cyclooctanone with nitrodienes and nitroolefins catalyzed by a hydroquinine-based primary amine catalyst has been accomplished. The corresponding Michael adducts were obtained in good yields (up to 88%) with good to excellent diastereoselectivities (up to >100 : 1) and enantioselectivities (up to >99% ee). The absolute configuration of the Michael product was assigned by TDDFT simulation of the ECD spectrum. And the Michael products can be readily converted into analogues of cycloalkano[b] fused pyrrolidines.

The reaction allows the formation of xanthenones and chromans with three contiguous stereocenters with high to excellent enantioselectivity and moderate to mostly excellent diastereoselectivity.

A combination of copper powder and Selectfluor permits the generation of cationic copper species that efficiently catalyze 1,2-dicarbonylation of alkynes under mild conditions with water and dioxygen as inexpensive and environmentally benign sources of oxygen.

A gold(I)-catalyzed oxidative diketonization of alkynes by water in the presence of Selectfluor has been achieved. The application of the present protocol for the one-pot synthesis of quin­oxaline derivatives from alkynes and o-phenylenediamines has also been successful.

An approach for the synthesis of fluorinated indene derivatives has been developed via a gold-catalyzed three-component tandem reaction between allene esters, Selectfluor, and water.

A mild and efficient protocol for the synthesis of fluorinated pyrazoles has been developed via gold(I)-catalyzed tandem aminofluorination of alkynes in the presence of Selectfluor. This method offers a broad substrate scope.

The first highly enantioselective organocatalytic Michael addition of 4-hydroxycoumarins is reported.

An efficient and highly selective approach for the synthesis of functionalized 4H-chromenes has been developed via gold(III)-catalyzed condensation/annulation tandem reaction of ketones with phenols.

Today gold is without a doubt the “star metal” in chemistry because of the focus of attention on gold-catalyzed organic transformations in recent years. 1 , 2 , 3 , 4 , 5 , 6 , 7 Among various new ...

Tiefsee-Diels-Alder-Reaktion: Die asymmetrische organokatalytische Diels-Alder-Reaktion zwischen Cyclohexenonen und aromatischen Nitroolefinen gelingt in Meerwasser und gesattigter Kochsalzlosung. Die Reaktion verlauft als saurekatalysierte Enaminaktivierung uber eine einstufige konzertierte Addition (siehe Schema).

Efficient and stereoselective rearrangement catalyzed by only one mole-percent gold(I) chloride/silver(I) trifluoromethanesulfonate of Baylis-Hillman acetates afforded 2-(acetoxymethyl)alk-2-enoates under mild reaction conditions in good to high yields with 100% E-selectivity. For cyclohex-2-enone-derived Baylis-Hillman acetates, the reaction gave 2-alkylidenecyclohex-3-enones in good yields.

An enantioselective oxa-Michael-Henry reaction of substituted salicylaldehydes with nitroolefins that proceeds though an aromatic iminium activation (AIA) has been developed by using a chiral secondary amine organocatalyst and salicylic acid as a co-catalyst. The corresponding 3-nitro-2H-chromenes were obtained in moderate-to-good yields with up to 91% ee under mild conditions. Based on the experimental results and ESI-mass spectrometric detection of the intermediates, a plausible transition state has been proposed to explain the origin of the activation and the asymmetric induction.

The direct asymmetric Michael addition of ketones to nitroolefins catalyzed by 2-[(imidazol-2-ylthio)methyl]pyrrolidine, constructed from natural L-proline and imidazolylthio platforms, with salicylic acid as a co-catalyst has been developed to give the products in high yields (up to 95 %) and with excellent enantioselectivities (up to 99 % ee). The highly efficient catalytic performance may be attributed to the dual activation of the Michael substrates by the trifunctional organocatalysts and the co-catalyst salicylic acid, leading to the formation of a stable transition state complex through the synergic effect of hydrogen-bonding and electrostatic interactions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Benzene is nitrated by a novel atom‐economic nitration procedure with a NO2‐O2 system in the presence of a mixture of solid oxides and Ln(OTf)3. The only by‐product in this novel method is water. The efficiency of NO2 is much high than 50%, the theoretical efficiency of NO2 of the known methods. Among the solid oxides and Ln(OTf)3 studied, HZSM‐5 and Sm(OTf)3 were the most efficient catalysts in this process. Therewith, the yield of the benzene nitration reached 72.5%, calculated by NO2.

A novel class of pyrrolidine–pyridinium based organocatalysts has been developed and demonstrated to efficiently catalyze the asymmetric Michael addition reactions of unmodified cyclohexanone to nitroalkenes in the ionic liquid BMImBF 4 with up to 95% yield and nearly 100% ee. The catalytic system could be reused for four times and still retained high enantioselectivity. X-ray crystallographic analysis results suggested that a sterically hindered pyridinium moiety on the catalyst played an important role in the chiral induction.

2-(2,2,2-Trichloroethyl)alk-2-enoates could be formed in good E-selectivity by the reductive coupling of Baylis-Hillman acetates with tetrachloromethane in good 76-92% yields in the presence of catalytic Al/PbCl 2 and DMF.

Catalyzed by ytterbium(III) triflate, asymmetrical carbonate can be chemoselectively synthesized from alcohols and dimethyl carbonate (DMC) in moderate to good yield under the mild conditions.

Michael adducts [(III) and (V)] are synthesized in good yields and high enantioselectivities using a hydroquinine-based primary amine as catalyst.

A series of 4‐arylidene‐2‐phenyl‐5(4)‐oxazolones were synthesized from cyclodehydration–condensation of hippuric acid, aromatic aldehydes, and acetic anhydride catalyzed by ytterbium(III) triflate under mild conditions in excellent yields.

Imidazolium-supported-pyrrolidine-catalyzed asymmetric Michael addition reactions of unmodified ketones and aldehydes to nitroalkenes were performed in [BMIm]PF 6 to give products in up to 98% yield and 99% enantioselectivity. The catalytic system presented a synergistic effect in the improvement of reaction performance and could be recycled.

A novel class of chiral-amine-functionalized ionic liquids (CAFILs) has been synthesized efficiently from natural amino acids, and their structures have been determined by spectroscopic analysis and low temperature X-ray diffraction analysis. The CAFILs have been characterized by physical properties such as melting point, glass transition temperature, thermal degradation and specific rotation. NMR measurements indicate that the CAFILs may be promising alternatives in the field of chiral discrimination.

Ionic liquids (ILs) were for the first time found to be alternatively excellent media for the heterogeneously catalyzed hydrogenation of halonitrobenzenes to corresponding haloanilines over three type catalysts of Raney nickel, carbon-supported platinum and palladium. The ionic liquids give rise to higher selectivity and lower dehalogenation in the hydrogenating process compared with that observed in conventional organic solvents.

The reaction allows the formation of xanthenones and chromans with three contiguous stereocenters with high to excellent enantioselectivity and moderate to mostly excellent diastereoselectivity.

A novel and facile C-H bond fluorination proceeds under remarkably mild conditions (close to room temperature in most cases). Both aromatic and olefinic C(sp(2))-H bonds with a wide range of electronic properties are selectively fluorinated in the presence of a catalytic amount of simple, cheap, and nontoxic nitrate as the promoter. A Pd(II)/Pd(IV) catalytic cycle that is initiated by an in situ generated cationic [Pd(NO3)](+) species was proposed based on preliminary mechanistic studies.

The 1,2-dicarbonylation of alkynes with water and air as sources of oxygen is catalyzed by a cationic copper species generated in situ from copper powder and selectfluor.

A series of N-arylamides and imides were synthesized via reductive N-acylation of nitroarenes with red phosphorus and carboxylic acids, catalyzed by iodine or iodides; an I - /I 0 redox cycle was proposed to promote the reaction.

Promoted by a catalytic amount of cesium hydroxide monohydrate, unsymmetrical bis-allyl ethers consisting of an £ -allylic unit and a terminal allylic unit were formed via dimerization of Baylis-Hillman adducts in moderate to good yields at room temperature.

Gold(I)-catalyzed reaction of alkynes with selectfluor and water as oxygen source affords 1,2-diketones which can also be trapped with o-phenylenediamines to give quinoxaline derivatives.

The organocatalytic Michael reaction of ketones with γ-monohalonitrodienes catalyzed by chiral prolinethiol ether under solvent-free conditions was developed. The described method represents a novel approach for accessing highly functionalized monohaloalkenes with α, β-stereocenters of up to >99% ee.

The organocatalytic Michael reaction of ketones with γ-monohalonitrodienes catalyzed by chiral prolinethiol ether under solvent-free conditions was developed. The described method represents a novel approach for accessing highly functionalized monohaloalkenes with α, β-stereocenters of up to >99% ee.

A novel and eco-friendly method is described for the direct preparation of a series of ionic liquids containing alkylimidazolium-based cations and hexafluorophosphate-based (or tetra­-fluoroborate-based) anions in a one-pot procedure by using ionic liquids themselves as solvents.

It is found that Au-mediated treatment of allene esters such as (I), (III), (Va), and (Vb) with Selectfluor and water allows an efficient access to biologically important fluoroindene derivatives.

A unique gold(I)-catalyzed highly atom-economic synthesis of 1,5-benzodiazepines directly from o-phenylenediamines and alkynes has been achieved for the first time.

The procedure allows an efficient and selective access to biologically important pyranocoumarins.

Fluorinated pyrazoles, interesting building blocks for pharmaceuticals and pesticides, are produced in a simple one-pot reaction at room temperature.

An efficient and selective approach for the synthesis of functionalized pyranocoumarins has been developed via a gold(III)-catalyzed tandem conjugate addition/annulation reaction of 4-hydroxycoumarins with α,β-unsaturated ketones.

The first example of palladium-catalyzed direct ortho-nitration of aryl C—H bonds is presented.

The first example of palladium-catalyzed direct ortho-nitration of aryl C—H bonds is presented.

A highly regioselective protocol for the synthesis of 3-carbonylated benzofuran derivatives has been developed involving the gold(III)-catalyzed tandem condensation/rearrangement/cyclization reaction of O-arylhydroxylamines with 1,3-dicarbonyl compounds.

The first highly enantioselective organocatalytic Michael addition of 4-hydroxycoumarins is reported.

An efficient and highly selective approach for the synthesis of functionalized 4H-chromenes has been developed via gold(III)-catalyzed condensation/annulation tandem reaction of ketones with phenols.

Novel SO3H-functionalized ionic liquids bearing two alkyl sulfonic acid groups in the imidazolium cations were designed and successfully applied as catalysts for the one-pot Fischer indole synthesis in water medium. The sequence of the catalytic activity observed in the transformation was in good agreement with the Bronsted acidity order determined by the Hammett method. Various types of indoles from single-carbonyl ketones/aldehydes and cyclohexandiones were provided in 68–96% yields using the catalytic system of [(HSO3-p)2im][HSO4]/H2O. The indole products could be conveniently separated from the reaction mixture by filtration and the dissolved catalyst could be regenerated by treatment with a strongly acidic cation exchange resin, which meant the whole process was performed in water without using any organic solvents.

Today gold is without a doubt the “star metal” in chemistry because of the focus of attention on gold-catalyzed organic transformations in recent years. 1 , 2 , 3 , 4 , 5 , 6 , 7 Among various new ...