Reductive Denitration of Nitroarenes

Kashihara, Myuto; Yadav, Mahipal; Nakao, Yoshiaki

doi:10.1021/acs.orglett.8b00430

Cited by 48 publications

(19 citation statements)

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“…The yields of the reduced compounds were determined by 1 H NMR. All hydrogenated compounds are well‐known compounds in the literature and their characterization data were in a good agreement with literature …”

Section: Methodssupporting

confidence: 85%

“…All hydrogenated compounds are well-known compounds in the literature and their characterization data were in a good agreement with literature. [23][24][25][26][27][28][29] The experimental part for the synthesis of Cu 7 Pt 3 alloy NPs, their assembly on rGO and the catalysis of Cu 7 Pt 3 -rGO in the transfer hydrogenation of various organic compounds is summarized by the Scheme 1.…”

Section: Assembly Of Nps On Rgomentioning

confidence: 99%

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Monodisperse CuPt alloy nanoparticles assembled on reduced graphene oxide as catalysts in the transfer hydrogenation of various functional organic groups

Ganjehyan

Nişancı²,

Sevim

et al. 2019

Applied Organom Chemis

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We present herein a new nanocatalyst, namely binary CuPt alloy nanoparticles (NPs) supported on reduced graphene oxide (CuPt‐rGO), as a highly active heterogeneous catalyst for the transfer hydrogenation (TH) protocol that is demonstrated to be applicable over the reduction of various unsaturated organic compounds (olefins, aldehydes/ketones and nitroarenes) in aqueous solutions at room temperature. CuPt alloy NPs were synthesized by the co‐reduction of metal (II) acetylacetonates by borane‐tert‐butylamine (BTB) complex in hot oleylamine (OAm) solution and then assembled on reduced graphene oxide (rGO) via ultrasonic‐assisted liquid phase self‐assembly method. The structure of yielded CuPt NPs and CuPt‐rGO nanocatalyst were characterized by TEM, XRD and ICP‐MS. The activity of Cu7Pt3‐rGO nanocatalysts were then tested for the THs that were conducted in a commercially available high‐pressure tube using water as sole solvent and ammonia borane as a hydrogen donor at room temperature. The presented catalytic TH protocol was successfully applied over nitroarenes, olefines and aldehydes/ketones, and all the tested compounds were converted to corresponding reduction products with the yields reaching up to 99% under ambient conditions. Moreover, the Cu7Pt3‐rGO nanocatalyst was also reusable in the TH by providing 99% yield after five consecutive runs in TH of nitrobenzene as an example.

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Section: Methodssupporting

confidence: 85%

Section: Assembly Of Nps On Rgomentioning

confidence: 99%

Monodisperse CuPt alloy nanoparticles assembled on reduced graphene oxide as catalysts in the transfer hydrogenation of various functional organic groups

Ganjehyan

Nişancı²,

Sevim

et al. 2019

Applied Organom Chemis

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“…Second, the functional-group tolerance should be improved. The Ar–NO 2 bond is essentially least reactive among the Ar–X bonds that are capable of engaging in oxidative additions, ,, which excludes the possibility of coexistence of these bonds and requires relatively harsh conditions upon activating nitroarenes. We hope that this Account will serve as a starting point for chemists to make further progress in this field.…”

Section: Discussionmentioning

confidence: 99%

“…The reduction of nitroarenes usually provides N-containing products, such as amines, hydroxylamines, and nitroso compounds, , as their low-lying LUMO usually spreads over the NO 2 group. Substitution of the whole nitro functionality by hydrogen is, thus, quite difficult and has been achieved only for special substrates. − On the contrary, our protocol, in which the Ar–NO 2 bond is directly cleaved, could be applied to the reductive denitration of nitroarenes . We discovered that the use of hydrosilane reductants typically results in the conventional reduction of the nitro group to an amino group, whereas secondary alcohols, especially 2-propanol are effective hydride donors in this system to deliver the parent aromatics (Scheme ).…”

Section: Reductive Denitration Of Nitroarenesmentioning

confidence: 99%

“…31−35 On the contrary, our protocol, in which the Ar−NO 2 bond is directly cleaved, could be applied to the reductive denitration of nitroarenes. 36 We discovered that the use of hydrosilane reductants typically results in the conventional reduction of the nitro group to an amino group, whereas secondary alcohols, especially 2propanol 37 are effective hydride donors in this system to deliver the parent aromatics (Scheme 8).…”

Section: Reductive Denitration Of Nitroarenesmentioning

confidence: 99%

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Cross-Coupling Reactions of Nitroarenes

Kashihara

Nakao

2021

Acc. Chem. Res.

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Metrics & MoreArticle Recommendations CONSPECTUS: Cross-coupling reactions are powerful synthetic tools to construct diverse chemical bonds often found in, for example, advanced materials and pharmaceuticals. Since their discovery, haloarenes have habitually been used as electrophilic coupling partners both in academic and industrial contexts. However, concerning the efficiency and the often-negative environmental impact of haloarene-based cross-coupling processes, more readily available, inexpensive, and environmentally friendly electrophiles have been explored. Nitroarenes, for example, are obtained from the facile nitration of aromatic compounds and, thus, represent one of the most easy-to-access feedstock electrophiles. Furthermore, their electron-deficient arene core can be functionalized easily and site-selectively through a wide variety of reactions. Yet, despite these advantages and even though the direct transformation of the NO 2 group would be an attractive option in cross-coupling chemistry, it has so far remained difficult to convert nitroarenes via a cleavage of the Ar−NO 2 bond given the inherent reactivity (or the lack thereof) of the nitro group. Such denitrative conversion has been performed by a conventional sequence of reduction, diazotization, and Sandmeyer reactions, which severely lacks efficiency and generality. This Account summarizes our recent research progress on cross-coupling reactions that employ nitroarenes as electrophiles. First, we developed the Suzuki−Miyaura coupling of nitroarenes using a palladium/BrettPhos catalyst. This reaction proceeds via an (at the time) unprecedented oxidative addition of the Ar−NO 2 bond, which was supported by experimental results and theoretical calculations. A widely accepted catalytic cycle for Pd-catalyzed cross-couplings has since been extended to include nitroarenes as electrophiles, which significantly increases substrate generality. Second, this denitrative coupling protocol was applied to various bond-forming reactions, namely, Buchwald−Hartwig amination, etherification, and hydrogenation reactions. Such diversification has enhanced the utility of nitroarenes as cross-coupling partners. To develop each reaction, it was necessary to modify the reaction conditions as required to overcome the obstacles deriving from nitro functionality including transmetalation and side reactions, as well as oxidative addition. Third, we designed a new Pd/NHC catalyst that exhibits higher activity than Pd/BrettPhos. The improved performance of Pd/NHC system was supported by its strong electron-donicity and structural robustness, and it allows the reduction of the catalyst loading significantly, thus increasing the efficacy and practicality of this method. The field of nitroarene-based cross-coupling has just started to flourish. In addition to our original work, several research groups have already adopted Pd/BrettPhos or Pd/NHC catalysts to develop new denitrative functionalizations. The utility of nitroarenes in the context of organic synthesis should be now...

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2‐(Dicyclohexylphosphino)‐3,6‐Dimethoxy‐2′,4′,6′‐Triisopropyl‐1,1′‐Biphenyl

Nakao

2021

Encyclopedia of Reagents for Organic Synthesis

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Reductive Denitration of Nitroarenes

Cited by 48 publications

References 49 publications

Monodisperse CuPt alloy nanoparticles assembled on reduced graphene oxide as catalysts in the transfer hydrogenation of various functional organic groups

Monodisperse CuPt alloy nanoparticles assembled on reduced graphene oxide as catalysts in the transfer hydrogenation of various functional organic groups

Cross-Coupling Reactions of Nitroarenes

2‐(Dicyclohexylphosphino)‐3,6‐Dimethoxy‐2′,4′,6′‐Triisopropyl‐1,1′‐Biphenyl

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