Jiaqing Wang

Highly Efficient Synthesis of N-Substituted Isoindolinones and Phthalazinones Using Pt Nanowires as Catalysts

A series of N-substituted isoindolinones have been successfully synthesized through the reductive C-N coupling and intramolecular amidation of 2-carboxybenzaldehyde and amines. This one-pot synthesis gives excellent yields using ultrathin Pt nanowires as catalysts under 1 bar of hydrogen. These unsupported catalysts can also be used for the synthesis of phthalazinones in high yield when hydrazine or phenyl hydrazine is used instead of amines.

Common metal of copper(0) as an efficient catalyst for preparation of nitriles and imines by controlling additives

A novel, efficient, convenient and environmentally friendly approach for the synthesis of nitriles and imines from primary amines has been developed. Using commercially available red copper as the catalyst, ammonium bromide as the co-catalyst and molecular oxygen as the sole oxidant, nitriles and imines can be afforded in high yields through benzylic oxidation.

Reversible Hydrogenation–Oxidative Dehydrogenation of Quinolines over a Highly Active Pt Nanowire Catalyst under Mild Conditions

Catalytic hydrogenation (reduction) and dehydrogenation (oxidation) reactions are of fundamental importance in the synthesis of organic molecules. The hydrogenation of aldehydes/ketones and imines yields the corresponding alcohols and amines. In the reverse direction, dehydrogenation of alcohols and amines forms the corresponding aldehydes/ketones and imines. The catalytic hydrogenations and dehydrogenations of N-heterocycles are particularly important transformations, as both saturated and unsaturated heterocycles are important structural units in natural products and pharmaceuticals. Previous methods for the hydrogenation of N-heterocycles have been catalyzed with homogeneous precious-metal catalysts, such as Ir, Ru, Rh, and Mo. Those catalytic systems all exhibit high activity and selectivity, but separation of the catalyst from the reaction mixture is quite difficult, and amines in particular suffer from contamination by the heavy-metal ions. Heterogeneous catalysis has also been used for the hydrogenation of N-heterocycles. Liao and Shi used Pd nanoparticles supported on tannin-grafted collagen fibers as a recyclable catalyst for the hydrogenation of quinoline. This catalyst showed excellent catalytic activity at an initial hydrogen pressure of 2 MPa. Bianchini found that silica-supported Pd nanoparticles could catalyze the hydrogenation of 1,10-phenanthroline at 30 bar (1 bar = 100 kPa) of hydrogen. Raney-Ni can also be used as a catalyst for the hydrogenation of phenanthrolines with good to excellent yields under 27 bar hydrogen pressure. As encouraging as these results are, the process is not suitable for industrial production because of the high working pressure. It is also energy intensive and suffers from some safety issues. Therefore, the development of a heterogeneous metal catalyst with superior catalytic activity and reusability is a very attractive research target. Kobayashi reported that sub-nanometer-sized Pd clusters stabilized by random copolymers act as catalysts for the hydrogenation of quinoline to 1,2,3,4-terahydroquinoline under mild reaction conditions. Recently, Au/TiO2, [11] Rh/AlO(OH), and heterogeneous multimetallic nanoparticle catalysts (72 catalysts based on Rh, Pt, Ir, and Ru) supported on metal oxides were also screened. They also need high hydrogen pressure (more than 8 bar). Pd@OmpG-C3N4 [14] (OmpG = outer membrane protein G) is the best catalyst that has been reported for the hydrogenation of quinolones, and it shows high activity and selectivity under mild reaction conditions (1 bar hydrogen and 40–100 8C). Platinum oxide (PtO2) can also be used in the hydrogenation of N-heterocycles in good yields. However, the utilization of Pt-based catalysts has been less investigated, even though Pt is regarded as one of the best metal catalysts for hydrogen activation. Kobayashi successfully applied polymer-incarcerated Pt nanoparticles (<3 nm) to the catalytic hydrogenation of unsaturated compounds including heterocycles in good yields under mild reaction conditions [5 atm of hydrogen (1 atm = 101.3 kPa)] . Somorjai and Yang demonstrated that the structure of the nanomaterials can affect the selectivity of the reactions: Pt nanocubes were used as a catalyst for the hydrogenation of pyrrole, and they showed selectivity towards n-butylamine that was higher than that shown by nanopolyhedra. These reported Pt-based catalysts are highly active and selective, which encouraged us to explore Pt-based heterogeneous catalysts in the hydrogenation of N-heterocycles. The direct oxidation of saturated N-heterocycles is an equally important organic transformation, as the structure unit can be found in many biologically active natural products and pharmacologically active molecules. Pd/C as a commercial catalyst proved to be effective in the oxidation of 1,2,3,4-tetrahydroquinolines to quinolines under mild reaction conditions. Ru-based catalysts can also be used in the oxidation of N-heterocycles to provide the products in good to excellent yields. Pt has proved to be one of the best catalysts for oxidation and has also been used as a heterogeneous catalyst in the oxidation of saturated N-heterocycles. Kaneda et al. found that supported Cu nanoparticles can be used in the dehydrogenation of 1,2,3,4-tetrahydroquinoline at 150 8C with the evolution of hydrogen gas. This is good for hydrogen transformations with organic molecules. This catalyst also shows excellent catalytic activity and selectivity for the hydrogenation of quinoline, and it is the first catalytic system that can be used in the hydrogenation of quinoline and in the dehydrogenation of hydrogenated quinoline. However, oxidative dehydrogenation is also an important transformation of organic molecules, and to the best of our knowledge, no catalytic system has been reported that can be used as an effective cat[a] D. Ge, Dr. L. Hu, J. Wang, Prof. X. Li, F. Qi, Prof. J. Lu, Prof. X. Cao, Prof. H. Gu Key Laboratory of Organic Synthesis of Jiangsu Province College of Chemistry, Chemical Engineering and Materials Science Soochow University, Suzhou 215123 (China) Fax: (+ 86) 512-65880905 E-mail : xqcao@suda.edu.cn hongwei@suda.edu.cn Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/cctc.201300136.

Novel Metal Nanomaterials and Their Catalytic Applications

In the rapidly developing areas of nanotechnology, nano-scale materials as heterogeneous catalysts in the synthesis of organic molecules have gotten more and more attention. In this review, we will summarize the synthesis of several new types of noble metal nanostructures (FePt@Cu nanowires, Pt@Fe2O3 nanowires and bimetallic Pt@Ir nanocomplexes; Pt-Au heterostructures, Au-Pt bimetallic nanocomplexes and Pt/Pd bimetallic nanodendrites; Au nanowires, CuO@Ag nanowires and a series of Pd nanocatalysts) and their new catalytic applications in our group, to establish heterogeneous catalytic system in “green” environments. Further study shows that these materials have a higher catalytic activity and selectivity than previously reported nanocrystal catalysts in organic reactions, or show a superior electro-catalytic activity for the oxidation of methanol. The whole process might have a great impact to resolve the energy crisis and the environmental crisis that were caused by traditional chemical engineering. Furthermore, we hope that this article will provide a reference point for the noble metal nanomaterials’ development that leads to new opportunities in nanocatalysis.

Facile synthesis of magnetic core–shell nanocomposites for MRI and CT bimodal imaging

With the development of nanotechnology, nanocomposites have been used as bimodal contrast agents for magnetic resonance (MR) and computed tomography (CT) imaging. We have developed a facile method for the synthesis of iron oxide@bismuth sulfide magnetic core-shell nanocomposites. These bifunctional nanocomposites can be made water-soluble via PEG coating and present strong MRI/CT contrast enhancement. Evaluation of cytotoxicity by MTT assay shows that the nanocomposites have low cytotoxicity. The results illustrate that the nanocomposites have great potential as bimodal imaging agents for MR/CT.

Preparation of a γ‐Fe2O3/Ag Nanowire Coaxial Nanocable for High‐Performance Lithium‐Ion Batteries

In this study, we report the design and synthesis of a silver nanowire-γ-Fe2 O3 coaxial nanocable architecture (Ag NWs@γ-Fe2 O3 nanocable) through mild oxidation of [Fe(CO)5 ] on the surface of silver nanowires followed by a calcination process. After optimization of the structural design, the Ag NWs@γ-Fe2 O3 nanocable could deliver superior lithium storage performance in terms of high reversible capacity, good rate performance, and excellent stability, such as a high reversible capacity of about 890 mA h g(-1) after 60 cycles at a current rate of 0.1 C (1.0 C=1005 mA g(-1) ). The reversible capacity remains as high as about 550 mA h g(-1) even at a high current rate of 2.0 C. This dramatic performance is mainly attributed to the smart coaxial design, which can not only alleviate the large volume change and prevent the aggregation of γ-Fe2 O3 nanoparticles, but also enables good conductivity and thus enhances fast charge transfer. The unique structural features of the Ag NWs@γ-Fe2 O3 nanocable represent a promising anode material in lithium-ion battery applications.

Catalysis by Pd nanoclusters generated in situ of high-efficiency synthesis of aromatic azo compounds from nitroaromatics under H2 atmosphere

A facile and efficient catalytic system based on Pd nanoclusters generated in situ from Pd(acac)2 was developed for the synthesis of various aromatic azo compounds (AAzos) by hydrogenation of the corresponding nitroaromatics, using H2 as the sole reductant, under mild reaction conditions.

Facile synthesis of Au-Pt bimetallic nanocomplexes for direct oxidation of methanol and formic acid†

Au–Pt bimetallic nanocomplexes were synthesized and the composition and morphology of the nanocomplexes could be easily controlled by a facile synthesis method. The eletrochemical activity and stability of the nanocomplexes can be optimized by tuning their Au-to-Pt molar ratio. The efficient electrocatalytic performance is confirmed by direct oxidation of methanol and formic acid.

Highly efficient synthesis of azos catalyzed by the common metal copper (0) through oxidative coupling reactions

A facile and efficient approach to synthesize symmetric, asymmetric and bridged aromatic azo compounds (AAzos) from aromatic amines was developed by using red copper as catalyst. Despite numerous efforts towards the catalytic synthesis of symmetric and asymmetric AAzos derivatives, most reactions present certain drawbacks inhibiting their industrial applications, such as laborious multi-step processes, harsh reaction conditions and expensive reagents. And the synthesis of bridged azos had low yields before. With the presence of ammonium bromide as co-catalyst, pyridine as a ligand and molecular dioxygen as a sole oxidative reagent, red copper, a common and abundant metal in nature, exhibited unexpected catalytic activity towards the preparation of AAzos in high yields via one-step reaction, making this catalyst an attractive candidate for industrial and synthetic applications.

The synthesis of cyclohexenone using L-proline immobilized on a silica gel catalyst by a continuous-flow approach

A facile and convenient method for the synthesis of cyclohexenone compounds was developed using an L-proline immobilized silica gel catalyst combined with a continuous-flow approach. Because of the mild reaction conditions, ease of catalyst recyclability, and product isolation, this reaction approach can potentially be used in a facile scale-up reaction or in industrial applications.