Selective Reduction of Nitroarenes with Silanes Catalyzed by Nickel N-Heterocyclic Carbene Complexes (original) (raw)
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Advanced Synthesis & Catalysis, 2010
The reduction of aromatic nitro compounds to the corresponding amines with silanes catalyzed by high valent oxo-rhenium complexes is reported. The catalytic systems PhMe 2 SiH/ReIO 2 (PPh 3 ) 2 (5 mol %) and PhMe 2 SiH/ReOCl 3 (PPh 3 ) 2 (5 mol %) reduced efficiently a series of aromatic nitro compounds in the presence of a wide range of functional groups such as ester, halo, amide, sulfone, lactone, and benzyl. This methodology also allowed the regioselective reduction of dinitrobenzenes to the corresponding nitroanilines and the reduction of an aromatic nitro group in presence of an aliphatic nitro group.
Molecules, 2021
Recently, N-substituted anilines have been the object of increasing research interest in the field of organic chemistry due to their role as key intermediates for the synthesis of important compounds such as polymers, dyes, drugs, agrochemicals and pharmaceutical products. Among the various methods reported in literature for the formation of C–N bonds to access secondary anilines, the one-pot reductive amination of aldehydes with nitroarenes is the most interesting procedure, because it allows to obtain diverse N-substituted aryl amines by simple reduction of nitro compounds followed by condensation with aldehydes and subsequent reduction of the imine intermediates. These kinds of tandem reactions are generally catalyzed by transition metal-based catalysts, mainly potentially reusable metal nanoparticles. The rapid growth in the last years in the field of metal-based heterogeneous catalysts for the one-pot reductive amination of aldehydes with nitroarenes demands for a review on the...
Catalysis Letters, 2008
Various nitroaromatics are successfully reduced to amines with 100% conversion and selectivity in methanol at low temperature (≈5 °C), by using versatile system of 5% Ni–SiO2 catalyst and NaBH4 and in situ generation of Ni boride. The catalytic efficiency of Ni loading (5%, 10% and 15%) with silica or titania as support materials is investigated for reduction of nitrobenzene. The Ni–titania/NaBH4 system recorded lower conversion and selectivity. The IR studies indicate that silica support does not have free –OH group on its surface. Thus the nickel boride is anchored to the silica to facilitate the catalytic process.
The catalytic reduction of nitroarenes under various catalytic systems has been widely reported in the flood of publications during last twenty years. This reaction has become a benchmark for testing catalytic activity of inorganic nanoparticles stabilized in various systems. This tutorial review presents design and classification of inorganic nanocatalysts along with their stabilizing agents used for catalytic reduction of nitroarenes. The techniques used for characterization of catalysts have been highlighted in this review. The mechanism of catalytic reduction has been described in a tutorial way. Factors affecting the rate of reduction of nitroarenes in the presence of metal nanoparticles stabilized in poly-electrolyte brushes, polyionic liquids, micelles, den-drimers, and microgels have been discussed for further development in this area.
Molecular Catalysis, 2018
Polymer supported nickel nanoparticles, generated by calcination (N2 to 300 °C, 30 min) of a Ni(II) containing polyacrylamide, catalyzed the hydrogenation of nitroarenes to anilines in water at room temperature in the presence of NaBH4. The protocol generally favored the formation of the desired aniline as single product in high yields with short reaction times and proved to be highly selective in the hydrogenation of halonitrobenzene to haloaniline. The catalyst displayed excellent recyclability over fifth cycles and no leaching of metal into solution occurred, which made the overall system ecofriendly and economic. STEM analyses revealed that the thermally formed Ni nanoparticles turned into cubic nanotwins under reaction conditions, which remained almost unchanged with the recycles .
1998
Homogeneous catalytic reduction of nitrobenzene to aniline by cis-[Rh(CO)2(amine)2]PF6 (amine = 4-picoline, 3-picoline, 2-picoline, pyridine, 3,5-lutidine or 2,6-lutidine) in aqueous amine 2/8, v/v, P(CO) = 0.9 atm, T = 100C, [Rh] = 10 mM under water-gas shift reaction conditions is described. The effect of various amines as additives was examined.
Tetrahedron Letters, 2012
Anilines are one of the important chemical feedstocks and are utilized for the preparation of a variety of pharmaceuticals, agrochemicals, pigments, and dyes. In this context, the catalytic reduction of nitro functionality is an industrially vital process for the synthesis of aniline derivatives. Herein, we report an efficient nanosized bimetallic Pd−Au/TiO 2 nanomaterial which is proved to be quite efficient for rapid catalytic hydrogen transfer reduction of nitroarenes into corresponding amines. Significantly, the reduction process is successful under solvent-free and mild green atmospheric conditions. Bimetallic Pd−Au nanoparticles served as the active center, and TiO 2 played as a support in hydrogen transfer from the source hydrazine monohydrate. Typical results highlighted that the reactions were very rapid and the products were obtained in good to excellent yields. Significantly, the process was successful in the presence of a very low amount catalyst (0.1 mol %). Furthermore, the reaction showed good chemoselectivity and compatiblity with double or triple bond, aldehyde, ketone, and ester functionalities on the aromatic ring. Typical results indicated the true heterogeneous nature of the Pd−Au/TiO 2 nanocatalyst, where the catalyst retained the activity, without loss of its activity.