Xinjiang Cui

Nano-gold catalysis in fine chemical synthesis.

the National Natural Science Foundation of China (21073208);the Chinese Academy of Sciences

Copper‐Catalyzed Alkylation of Sulfonamides with Alcohols

the Chinese Academy of Sciences;the DFG (SPP 1118 and Leibniz Prize), and the BMBF. F. Shi thanks the Alexander-von-Humboldt-Stiftung for an AvH Fellowship

Organic Ligand-Free Alkylation of Amines, Carboxamides, Sulfonamides, and Ketones by Using Alcohols Catalyzed by Heterogeneous Ag/Mo Oxides

Complicated and expensive organic ligands are normally essential in fine chemical synthesis at preparative or industrial levels. The synthesis of fine chemicals by using heterogeneous catalyst systems without additive organic ligand is highly desirable but severely limited due to their poor generality and rigorous reaction conditions. Here, we show the results of carbon-nitrogen or carbon-carbon bond formation catalyzed by an Ag/Mo hybrid material with specific Ag(6) Mo(10) O(33) crystal structure. 48 nitrogen- or oxygen-containing compounds, that is, amines, carboxamides, sulfonamides, and ketones, were successfully synthesized through a borrowing-hydrogen mechanism. Up to 99 % isolated yields were obtained under relatively mild conditions without additive organic ligand. The catalytic process shows promise for the efficient and economic synthesis of amine, carboxamide, sulfonamide, and ketone derivatives because of the simplicity of the system and ease of operation.

Synthesis and Characterization of Iron–Nitrogen-Doped Graphene/Core–Shell Catalysts: Efficient Oxidative Dehydrogenation of N-Heterocycles

An important goal for nanocatalysis is the development of flexible and efficient methods for preparing active and stable core-shell catalysts. In this respect, we present the synthesis and characterization of iron oxides surrounded by nitrogen-doped-graphene shells immobilized on carbon support (labeled FeOx@NGr-C). Active catalytic materials are obtained in a simple, scalable and two-step method via pyrolysis of iron acetate and phenanthroline and subsequent selective leaching. The optimized FeOx@NGr-C catalyst showed high activity in oxidative dehydrogenations of several N-heterocycles. The utility of this benign methodology is demonstrated by the synthesis of pharmaceutically relevant quinolines. In addition, mechanistic studies prove that the reaction progresses via superoxide radical anions (·O2(-)).

Methylation of amines, nitrobenzenes and aromatic nitriles with carbon dioxide and molecular hydrogen

CO2/H2 was successfully employed in alkylation reactions by performing CO2 reduction and amine N-methylation in one-pot. In the presence of a simple CuAlOx catalyst, N-methyl or N,N-dimethyl amines with different structures can be selectively synthesized with up to 96% yields by applying amine, nitrobenzene and nitrile as starting materials.

Development of a General Non‐Noble Metal Catalyst for the Benign Amination of Alcohols with Amines and Ammonia

The N-alkylation of amines or ammonia with alcohols is a valuable route for the synthesis of N-alkyl amines. However, as a potentially clean and economic choice for N-alkyl amine synthesis, non-noble metal catalysts with high activity and good selectivity are rarely reported. Normally, they are severely limited due to low activity and poor generality. Herein, a simple NiCuFeOx catalyst was designed and prepared for the N-alkylation of ammonia or amines with alcohol or primary amines. N-alkyl amines with various structures were successfully synthesized in moderate to excellent yields in the absence of organic ligands and bases. Typically, primary amines could be efficiently transformed into secondary amines and N-heterocyclic compounds, and secondary amines could be N-alkylated to synthesize tertiary amines. Note that primary and secondary amines could be produced through a one-pot reaction of ammonia and alcohols. In addition to excellent catalytic performance, the catalyst itself possesses outstanding superiority, that is, it is air and moisture stable. Moreover, the magnetic property of this catalyst makes it easily separable from the reaction mixture and it could be recovered and reused for several runs without obvious deactivation.

Ruthenium-catalyzed nitro and nitrile compounds coupling with alcohols: alternative route for N-substituted amine synthesis.

Amines and their derivatives play critical roles as building blocks, functional linkages, and key moieties in peptides, polymers, and many natural products and pharmaceuticals. In addition, a plenty of naturally and man-made bioactive compounds, such as amino acids, nucleic acids, and enzymes, contain N-substituted amines. [1] N-Substituted amines are usually prepared by the alkylation of amines with halides. [2] However, this method is problematic due to overalkyation, the toxic nature of halides and related alkylating reagents, and the generation of stoichiometric unwanted byproducts. In many cases, N-substituted amines could also be synthesized by hydroamination [3] and hydroaminomethylation [4] reactions. An environmental benign procedure to produce Nsubstituted amines is the catalytic alkylation of amines with alcohols. [5] Clearly, alcohols are readily available, nonexpensive, and nontoxic, and water is the only byproduct theoretically. Thus, the reaction is environmentally friendly intrinsically. However, employing alcohols as alkylation reagents is severely limited because of the poor electrophilicity of most alcohols. The borrowing-hydrogen technology makes the use of alcohol as alkylation reagent more facile. In this method, the poorly electrophilic alcohol was converted into aldehyde with the liberation of metal hydride. The aldehyde reacts with amine to form imine with water as byproduct. The imine was then reduced by the metal hydride to obtain the final product. This interesting transformation has been studied extensively since the reports by Grigg [6] and Watanabe, [7] and various transition-metal catalysts including ruthenium [8] and iridium [9] complexes were studied subsequently. Despite the importance of the N-substituted amines, to date, the selective synthesis of N-substituted amines through borrowing hydrogen methods was restricted to the reaction of amines with alcohols. It is still a challenge to find other ways to achieve the amination of alcohols. It is known that primary amines are normally produced by the hydrogenation of nitrobenzenes and benzonitriles. [10] The transfer hydrogenation reaction of nitroarenes and nitriles [11] by alcohols has been long known in the literature, as has the condensation reaction of amines with alcohols . [5, 8] However, these reactions have not previously been performed in one pot in the presence of a single catalytic system. It would be an ideal reaction if substituted amines could be synthesized in one step from nitro or nitrile compounds and alcohols. In this way, the specific equipment, rigorous reaction conditions, and complicated operations could be avoided. In one word, a multistep reaction would be realized in one-pot. Based on the continuous interest in the developing of simple and economic method for the synthesis of Nsubstituted secondary amine, we tried a new route to realize the amination of alcohols to secondary amine from nitro or nitrile compounds directly (Scheme 1).

Carbon-catalysed reductive hydrogen atom transfer reactions

Generally, transition metal catalysts are essential for the reductive hydrogen atom transfer reaction, which is also known as the transfer hydrogenation reaction or the borrowing-hydrogen reaction. It has been reported that graphene can be an active catalyst in ethylene and nitrobenzene reductions, but no report has described carbon-based materials as catalysts for alcohol amination via the borrowing-hydrogen reaction mechanism. Here we show the results from the preparation, characterization and catalytic performance investigation of carbon catalysts in transition metal-free borrowing-hydrogen reactions using alcohol amination and nitro compound/ketone reduction as model reactions. XPS, XRD, SEM, FT-IR and N2 adsorption-desorption studies revealed that C=O group in the carbon catalysts may be a possible catalytically active site, and high surface area is important for gaining high activity. The activity of the carbon catalyst remained unchanged after reuse. This study provides an attractive and useful methodology for a wider range of applications.

Amine formylation via carbon dioxide recycling catalyzed by a simple and efficient heterogeneous palladium catalyst

A simple and efficient Pd/Al2O3-NR-RD catalyst was prepared by depositing palladium on a shape controllable Al2O3-NR support through a two-step process that involves hydrothermal synthesis of Al2O3-NRs followed by reductive-deposition of palladium. This catalyst showed high activity in the catalytic formylation of amines by CO2-H2 under mild conditions with up to 96% yield.

Lewis Acid Promoted Ruthenium(II)‐Catalyzed Etherifications by Selective Hydrogenation of Carboxylic Acids/Esters

Ethers are of fundamental importance in organic chemistry and they are an integral part of valuable flavors, fragrances, and numerous bioactive compounds. In general, the reduction of esters constitutes the most straightforward preparation of ethers. Unfortunately, this transformation requires large amounts of metal hydrides. Presented herein is a bifunctional catalyst system, consisting of Ru/phosphine complex and aluminum triflate, which allows selective synthesis of ethers by hydrogenation of esters or carboxylic acids. Different lactones were reduced in good yields to the desired products. Even challenging aromatic and aliphatic esters were reduced to the desired products. Notably, the in situ formed catalyst can be reused several times without any significant loss of activity.