Chemoselective Transfer Hydrogenation Of Nitroarenes Research Articles

Chemoselective Transfer Hydrogenation of Nitroarenes with Ammonia Borane Catalyzed by Copper N‐heterocyclic Carbene Complexes

Comprehensive SummaryHerein, we present a method for the homogeneous hydrogenation of nitroarenes to produce anilines using low catalyst loading (1 mo%) of copper N‐heterocyclic carbene complexes as the catalyst and ammonia borane as the source of hydrogen. A wide range of nitroarenes, featuring diverse functional groups, were selectively transformed into their corresponding primary aromatic amines with high yields. This process can be readily scaled up and exhibits compatibility with various sensitive functional groups, including halogen, trifluoromethyl, aminomethyl, alkenyl, cyano, ester, amide, and hydroxyl. Notably, this catalytic methodology finds application in the synthesis of essential drug compounds. Mechanistic investigations suggest that the in‐situ‐generated Cu‐H species may serve as active intermediates, with reduction pathways involving species such as azobenzene, 1,2‐diphenylhydrazine, nitrosobenzene, and N‐phenylhydroxylamine.

Ultra-small FeS2 nanoparticles for highly efficient chemoselective transfer hydrogenation of nitroarenes

Ultra-small FeS2 nanoparticles are shown to give superior catalytic performance in hydrogen transfer reactions for the synthesis of substituted anilines.

Isolated Iron Single-Atomic Site-Catalyzed Chemoselective Transfer Hydrogenation of Nitroarenes to Arylamines.

Selective hydrogenation of nitroarenes to arylamines is a great challenge because of the complicated mechanism and competitive hydrogenation of reducible functional groups. Isolated single-atomic site catalysts, benefitting from their uniform and well-defined catalytic sites, are promising to achieve high activity and selectivity. Herein, we prepared an isolated iron single-atomic catalyst supported on ordered mesoporous nitrogen-doped carbon (Fe1/N-C). The as-prepared Fe1/N-C showed excellent activity and tolerance for functional groups in the transfer hydrogenation of nitroarenes over hydrazine hydrate. Density functional theory calculations revealed that the single atomically dispersed, partially positively charged Fe atoms and the lowered energy barrier collectively contribute to the superior hydrogenation performances for nitroarenes.

Bifunctional Pincer Catalysts for Chemoselective Transfer Hydrogenation and Related Reactions

A comparative study on the chemoselective transfer hydrogenation of nitroarenes to anilines and related processes using FA as the hydrogen source is described; these processes are catalyzed by a series of pincer catalysts equipped with different functional groups in the secondary coordination sphere. Some new (4 and 5) as well as previously reported (1–3) catalysts belonging to the family of bifunctional PC(sp3)P pincer complexes were employed in this study The reported compounds exhibited remarkably different catalytic activity behavior, depending on the nature of the functional groups. Transfer hydrogenation of nitrobenzene with FA as a hydrogen source was probed using iridium complexes 3 or 4 as a catalyst. Under the same conditions, the analogous palladium complex was found to be useful for the selective amidation of aniline with light carboxylic acids.

Chemoselective transfer hydrogenation of nitroarenes, ketones and aldehydes using acylthiourea based Ru(II)(p-cymene) complexes as precatalysts

A new series of Ru(II)(η6-p-cymene) complexes (1–5) was synthesized from pyridine based acylthiourea ligands (L1-L5) and [Ru(η6-p-cymene)Cl2]2. All the ligands and complexes were well characterized by UV-Visible, FT-IR, mass and 1H &13C NMR spectroscopic techniques. The molecular structures of the ligands (L1, L2, L4, and L5) and complex 1 were confirmed using single crystal X-ray diffraction study. The Ru(II)(η6-p-cymene) complexes (1–5) were proved to be efficient precatalysts for the transfer hydrogenation of carbonyl compounds and nitroarenes in the presence of 2-propanol as a hydrogen donor and KOH as a base. The catalytic transfer hydrogenation reactions were chemoselective towards the nitro group in presence of carbonyl group, which is a rare scenario in homogeneous catalysis. The catalyst was compatible with broad range of substrates which include furfural, quinone and many heterocycles. The catalytic reactions exhibited very high conversions (upto 100%) and excellent yields (upto 99%). Turn Over Number (TON) was found upto 990.

Molybdenum Carbide Catalysts for Chemoselective Transfer Hydrogenation of Nitroarenes

AbstractThe catalytic transfer hydrogenation of nitroarenes to corresponding amines is an important organic synthesis method in the process of industrial production. Molybdenum carbide catalysts were prepared by temperature‐programmed reduction of the as‐prepared molybdenum trioxide in the flowing 20% CH4/H2 and exhibited excellent catalytic performance for the reduction of nitroarenes under mild conditions. In spite of the presence of halogens and reducible substituents, the catalysts also deliver high chemoselectivity (>99%) for transformation nitroarenes to corresponding amines. The Cycling tests of molybdenum carbide catalysts demonstrated that it is highly stable and could easily be recovered by simple filtration for at least eight recycling reactions without decrease of catalytic activity and chemoselectivity.

Highly dispersed cobalt oxides nanoparticles on activated carbon fibres as efficient structured catalysts for the transfer hydrogenation of m-nitrostyrene

The facile preparation of structured catalysts featuring highly-dispersed non-precious metal (Fe, Ni, Co) oxide nanoparticles stabilized within a super-microporous network of activated carbon fibres (ACF) is described. The catalyst morphology was controlled over multiple levels from the nano-designed active phase up to the macro-structure of the ACF support. A range of physicochemical techniques was used to characterize the catalyst and rationalize the catalytic data during chemoselective transfer hydrogenation of nitroarenes. The challenging reduction of m-nitrostyrene containing an easily reducible vinyl-group was obtained under mild conditions with a near-quantitative yield of m-vinylaniline using hydrazine hydrate as the reducing agent over CoOx/ACF as a structured catalyst.

Chemoselective transfer hydrogenation of nitroarenes by highly dispersed Ni-Co BMNPs

Highly dispread Ni-Co bimetallic nanoparticles (Ni-Co BMNPs) are synthesized and applied as an efficient catalyst in the chemoselective transfer hydrogenation of nitroarenes (CTH) using hydrazine hydrate as the hydrogen donor. The BMNPs can efficiently catalyze the reduction reaction without any additives under mild conditions with high TOF. Significantly higher activity is achieved when compared with corresponding single-component catalysts, optimal composition of the Ni-Co BMNPs was screened which was proved to be crucial in both the selectivity and yields. Excellent performance of Ni-Co BMNPs can be ascribed to the improved dispersion of active sites on the BMNPs surface (compared with Ni NPs) and the electron transfer from cobalt to nickel.

A simple and efficient in situ generated ruthenium catalyst for chemoselective transfer hydrogenation of nitroarenes: kinetic and mechanistic studies and comparison with iridium systems

A convenient and highly efficient in situ generated Ru(ii) system for synthesizing functionalized amines and mechanistic studies and comparison with iridium systems is presented.

Immobilized Iron Metal-Containing Ionic Liquid-Catalyzed Chemoselective Transfer Hydrogenation of Nitroarenes into Anilines

The chemoselective transfer hydrogenation of nitroarenes into anilines was investigated using immobilized iron metal containing ionic liquid (ImmFe-IL) as a versatile heterogeneous catalyst. The present protocol has high atom efficiency with excellent chemosectivity and regioselectivity. Selective reduction of the nitro group was observed in the presence of other reducing functional groups such as nitrile, ketone, acid, amide, ester, halogens, hydroxyl, olefin, and heterocycles. The developed protocol is also highly selective toward conversion of dinitroarenes into nitroanilines. The present catalytic system uses environmentally benign ethylene glycol as a solvent which is inexpensive, easily available, nontoxic, nonvolatile, nonflammable, thermally stable, and biodegradable. The catalyst was reused up to four consecutive cycles with high activity and selectivity. The fresh catalyst and recycle catalyst was well characterized by XPS analysis.

Chemoselective Transfer Hydrogenation of Nitroarenes Catalyzed by Highly Dispersed, Supported Nickel Nanoparticles

A recyclable highly dispersed Ni/SiO2 catalyst was prepared by atomic layer deposition. Chemoselective reduction of nitroarenes was studied using the prepared Ni/SiO2 as the catalyst and hydrazine hydrate as a hydrogen donor. Different kinds of nitroarenes were converted to the corresponding anilines with high yields. The high activity of the catalysts could be a result of the highly dispersed Ni nanoparticles.

ChemInform Abstract: Base‐Free Chemoselective Transfer Hydrogenation of Nitroarenes to Anilines with Formic Acid as Hydrogen Source by a Reusable Heterogeneous Pd/ZrP Catalyst.

AbstractThe catalyst is recovered and reused in three additional cycles without loss of its activity.

Nitrogen-Doped Graphene-Activated Iron-Oxide-Based Nanocatalysts for Selective Transfer Hydrogenation of Nitroarenes

Nanoscaled iron oxides on carbon were modified with nitrogen-doped graphene (NGr) and found to be excellent catalysts for the chemoselective transfer hydrogenation of nitroarenes to anilines. Under standard reaction conditions, a variety of functionalized and structurally diverse anilines, which serve as key building blocks and central intermediates for fine and bulk chemicals, were synthesized in good to excellent yields.

ChemInform Abstract: Highly Efficient and Chemoselective Transfer Hydrogenation of Nitroarenes at Room Temperature over Magnetically Separable Fe—Ni Bimetallic Nanoparticles.

AbstractFe‐Ni nanoparticles are used as catalyst for the selective hydrogenation of nitroarenes (I) to anilines (II) as well as cinnamic ester (III) to 3‐phenylpropanoate (IV).

Base-free chemoselective transfer hydrogenation of nitroarenes to anilines with formic acid as hydrogen source by a reusable heterogeneous Pd/ZrP catalyst

A highly efficient, chemoselective, environmentally-benign method is developed for the catalytic transfer hydrogenation (CTH) of nitroarenes using FA as a hydrogen source. Various supported Pd catalysts were examined for this transformation, and Pd supported ZrP (Pd/ZrP) proved to be the best catalyst for CTH of nitrobenzene. Applicability of the Pd/ZrP catalyst is also explored for hydrogenation of various substituted nitroarenes. The Pd/ZrP catalyst showed high specificity for hydrogenation of nitro groups even in the presence of other reducible functional groups such as –CC, –COOCH3, and –CN. To investigate the reaction mechanism, a Hammett plot was obtained for CTH of p-substituted nitroarenes. The active site is thought to be in situ generated Pd(0) species as seen from XRD and TEM data. The Pd/ZrP catalyst is reusable at least up to 4 times while maintaining the same activity and selectivity. To the best of our knowledge, this is one of the best methodologies for CTH of nitroarenes under base-free conditions with high activity and chemoselectivity over heterogeneous Pd-based catalysts.

Highly efficient and chemoselective transfer hydrogenation of nitroarenes at room temperature over magnetically separable Fe–Ni bimetallic nanoparticles

A highly chemoselective catalytic transfer hydrogenation (CTH) of nitroarenes to corresponding amino derivatives is achieved with Fe–Ni bimetallic nanoparticles (Fe–Ni NP's) as the catalyst and NaBH4 at room temperature. Their catalytic efficiency is ascribed to the presence of Ni sites on the bimetallic surface that not only hinder the surface corrosion of the iron sites but also facilitate efficient electron flow from the catalyst surface to the adsorbed nitro compounds. This facet is corroborated with reusability studies as well as surface characterization of the catalyst before and after its repetitive usage. Thus, these nanoparticles efficiently catalyze the reduction of functionalized nitroarenes to corresponding amines without use of corrosive agents like base or other additives under ambient conditions and are easily separated by a laboratory magnet in an eco-friendly manner.

ChemInform Abstract: Chemoselective Transfer Hydrogenation of Nitroarenes, Aldehydes, and Ketones with Propan‐2‐ol Catalyzed by Ni‐Stabilized Zirconia.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Chemoselective transfer hydrogenation of nitroarenes, aldehydes and ketones with propan-2-ol catalysed by Ni-stabilized zirconia

T. T. Upadhya, S. P. Katdare, D. P. Sabde, V. Ramaswamy and A. Sudalai, Chem. Commun., 1997, 1119 DOI: 10.1039/A701518F