Selective Synthesis of Secondary Amines from Nitriles by a User‐Friendly Cobalt Catalyst

Sharma, Dipesh M.; Punji, Benudhar

doi:10.1002/adsc.201900586

Cited by 29 publications

(16 citation statements)

References 57 publications

(29 reference statements)

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“…Punji and Sharma studied the TH of nitriles to secondary amines using [Co(Xantphos)Cl 2 ]. [41] The transformation was found to be dependent on the amine-borane used; with H 3 N•BH 3 , the selective formation of symmetrical secondary amine was observed. When Me 2 HN•BH 3 was used and the reaction was performed in the presence of a second equivalent of amine, the synthesis of unsymmetrical amines resulted instead.…”

Section: Metal Catalysismentioning

confidence: 95%

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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: Metal Catalysismentioning

confidence: 95%

“…Punji and Sharma studied the TH of nitriles to secondary amines using [Co(Xantphos)Cl 2 ] [41] . The transformation was found to be dependent on the amine–borane used; with H 3 N⋅BH 3 , the selective formation of symmetrical secondary amine was observed.…”

Section: Catalyzed Classical Th Reactionsmentioning

confidence: 99%

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

2021

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“…34b The use of Co, Ni, and Mn precatalysts have been reported for TH of nitriles (Figure 1) into primary amines or products of partial hydrogenation as displayed in Figure 5. The synthetic versatility of this reaction is demonstrated by some examples, where selective formation of benzylamine (BA; Mn-5 17 and Co-2 35 ), N-benzylidene benzylamine (BBA; Ni-2 16 ), N,Ndibenzyl amine (DBA; Ni-2, 16 Co-3, 35 and Co-9 36 ), N-benzyl cyclohexylamine (BCA; Co-3 35 ), N-benzyl aniline (NBA; Co-9 36 ), and N-benzyl morpholine (NBM; Co-3 35 and Co-9 36 ) was observed. All of these works involved TH of benchmark benzonitrile (Figure 5).…”

Section: Th Of Nitriles: On the Way To Environmentally Benign Protocolsmentioning

confidence: 99%

Toward Amines, Imines, and Imidazoles: A Viewpoint on the 3d Transition-Metal-Catalyzed Homogeneous Hydrogenation of Nitriles

Garduño

Garcı́a

2020

ACS Catal.

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Mn-, Fe-, Co-, and Ni-based catalytic precursors have been reported for the homogeneous 3d transition-metal-catalyzed hydrogenation of nitriles. We present herein a critical assessment of such reports, emphasizing experimental setups, selectivity patterns, and mechanistic aspects fashioning this growing field. Moreover, its successes, drawbacks, and challenges are highlighted to outline what is next in the design of catalytic systems for future years.

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“…Amines are a highly important class of chemicals owing to their wide applicability on most distinctive fields 1, 2. They can be synthesized by several methods, namely, by hydroamination, hydroaminomethylation, reduction of nitriles and nitro compounds or reductive amination 3–7. Besides reductive amination all methods usually require the use of prefunctionalized and/or toxic compounds, leading to poor atom efficiency 8–10.…”

Section: Introductionmentioning

confidence: 99%

Amination of Cyclohexanol over a Ni‐Based Catalyst – Part II: Catalyst Stability and Reaction Pathway

Churro

Mendes²,

Araújo³

et al. 2021

Chem Eng & Technol

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Ni‐based catalysts present a highly interesting performance for the reductive amination of cyclohexanol (CHOL). The stability of a commercial Ni‐based catalyst was evaluated and a high stability over the tested time‐on‐stream (TOS) was observed. The reaction network was evaluated by analysis of selectivity profiles as a function of CHOL conversion. The formation of cyclohexylamine (CHA) was found to be consistent with the proposed borrowing hydrogen method (BHM). The formation of heavy‐end (HE) by‐products also follows the BHM pathway as parallel reaction. The effect of individual molar proportions of NH3 and H2 was evaluated. It was found that when H2 is present in a high excess, side reactions were favored, but its presence is mandatory towards keeping the catalyst active.

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Selective Synthesis of Secondary Amines from Nitriles by a User‐Friendly Cobalt Catalyst

Abstract: Scheme 1. General scheme for the hydrogenation of nitrile. Scheme 2. Examples of base-metal catalyzed reductions of nitriles to primary and secondary amines.

Cited by 29 publications

References 57 publications

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

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

Toward Amines, Imines, and Imidazoles: A Viewpoint on the 3d Transition-Metal-Catalyzed Homogeneous Hydrogenation of Nitriles

Amination of Cyclohexanol over a Ni‐Based Catalyst – Part II: Catalyst Stability and Reaction Pathway

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