Simple reversible fixation of a magnetic catalyst in a continuous flow system: ultrafast reduction of nitroarenes and subsequent reductive amination using ammonia borane

Kim, Hong Won; Byun, Sangmoon; Kim, Sang Woo; Kim, Ha Joon; Cao, Lei; Kang, Dong Yun; Cho, Ahra; Kim, Byeong Moon; Park, Jin Kyoon

doi:10.1039/c9cy02021g

Cited by 15 publications

(8 citation statements)

References 42 publications

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“…In contrast, we find that a plethora of examples using heterogeneous catalysts have been reported, [85] and we highlight only those which present productive mechanistic studies for the understanding of the reaction.…”

Section: Hydrogenation Reactionsmentioning

confidence: 82%

Amine–Boranes as Transfer Hydrogenation and Hydrogenation Reagents: A Mechanistic Perspective

2021

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Transfer hydrogenation (TH) has historically been dominated by Meerwein–Ponndorf–Verley (MPV) reactions. However, with growing interest in amine–boranes, not least ammonia–borane (H3N⋅BH3), as potential hydrogen storage materials, these compounds have also started to emerge as an alternative reagent in TH reactions. In this Review we discuss TH chemistry using H3N⋅BH3 and their analogues (amine–boranes and metal amidoboranes) as sacrificial hydrogen donors. Three distinct pathways were considered: 1) classical TH, 2) nonclassical TH, and 3) hydrogenation. Simple experimental mechanistic probes can be employed to distinguish which pathway is operating and computational analysis can corroborate or discount mechanisms. We find that the pathway in operation can be perturbed by changing the temperature, solvent, amine–borane, or even the substrate used in the system, and subsequently assignment of the mechanism can become nontrivial.

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Section: Hydrogenation Reactionsmentioning

confidence: 82%

Amine–Boranes as Transfer Hydrogenation and Hydrogenation Reagents: A Mechanistic Perspective

2021

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“…Pd−Pt−Fe 3 O 4 proved to be a very active and magnetically recyclable catalyst for chemoselective reduction of several nitroarenes with the use of ammonia borane (NH 3 BH 3 ) as a hydrogen source. These characteristics prompted Kim’s and Park’s groups to explore the use of Pd−Pt−Fe 3 O 4 as magnetically catalyst for developing a very fast stepwise RA from nitroarenes and aldehydes at room temperature using NH 3 BH 3 as reducing agent in a continuous flow system ( Scheme 57 ) [ 117 ]. The peculiarity of the flow system developed by these authors is that the catalyst was directly fixed in a simple perfluoroalkoxy alkanes (PFA) tubing with the aid of commercially available permanent neodymium magnets without the use of a special cartridge or column.…”

Section: Metal-catalyzed One-pot Reductive Amination Reactionmentioning

confidence: 99%

Metal-based Heterogeneous Catalysts for One-Pot Synthesis of Secondary Anilines from Nitroarenes and Aldehydes

et al. 2021

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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 state of the art with a special emphasis on the different kinds of metals used as catalysts and their recyclability features.

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“…Among various metal catalysts, Pd is traditionally known for its catalytic activity for hydrogenation reactions. Recently, Pd also proved to be an effective catalyst for transfer hydrogenation reactions [12,21–26] . Transfer hydrogenation involves the use of hydrogen sources such as sodium borohydride, isopropanol, formic acid, and hydrazine [27–30] .…”

Section: Introductionmentioning

confidence: 99%

“…Recently, Pd also proved to be an effective catalyst for transfer hydrogenation reactions. [12,[21][22][23][24][25][26] Transfer hydrogenation involves the use of hydrogen sources such as sodium borohydride, isopropanol, formic acid, and hydrazine. [27][28][29][30] It avoids direct usage of hazardous H 2 gas at high pressure and temperatures for hydrogenation reactions.…”

Section: Introductionmentioning

confidence: 99%

Hybridization of Palladium Nanoparticles with Aromatic‐Rich SU‐101 Metal‐Organic Framework for Effective Transfer Hydrogenation

et al. 2022

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Metal-organic frameworks (MOFs) are crystalline porous materials with designable pores. In this study, we loaded Pd nanoparticles onto π-electron rich pores of ellagic acid based SU-101 MOF (Bi 2 O(H 2 O) 2 (C 14 H 2 O 8 ) • nH 2 O) in order to surround Pd active sites with π-electron rich environment. The material has been explored for the transformation of 4-Nitro phenol (4-NP) to 4-Amino phenol (4-AP) using ammonia borane (AB). AB acted as efficient transfer hydrogenation agent compared to NaBH 4 because of its ability to transfer hydrogens at milder conditions.AB is safer and easy to handle compared to molecular hydrogen or NaBH 4 . The Pd NPs are loaded on to SU-101 using two methodologies. One by supporting preformed Pd NPs onto MOF surface (Pd-WCGA/SU-101) and the other by wet impregnation method (Pd/SU-101). The later method yields a material with strong interaction between Pd and SU-101. The Pd/SU-101 exhibited superior activity for 4-NP reduction (turn over frequency = 2421 h À 1 ) using AB due to an enrichment of 4-NP around Pd active sites by π-electron rich pore environment.

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Simple reversible fixation of a magnetic catalyst in a continuous flow system: ultrafast reduction of nitroarenes and subsequent reductive amination using ammonia borane

Abstract: Continuous reductive amination was performed using NH3BH3 through reversible magnetic bimetallic fixation at room temperature.

Cited by 15 publications

References 42 publications

Amine–Boranes as Transfer Hydrogenation and Hydrogenation Reagents: A Mechanistic Perspective

Amine–Boranes as Transfer Hydrogenation and Hydrogenation Reagents: A Mechanistic Perspective

Metal-based Heterogeneous Catalysts for One-Pot Synthesis of Secondary Anilines from Nitroarenes and Aldehydes

Hybridization of Palladium Nanoparticles with Aromatic‐Rich SU‐101 Metal‐Organic Framework for Effective Transfer Hydrogenation

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