Origins of high catalyst loading in copper(<scp>i</scp>)-catalysed Ullmann–Goldberg C–N coupling reactions

Sherborne, Grant J.; Adomeit, Sven; Menzel, Robert; Rabeah, Jabor; Brückner, Angelika; Fielding, Mark R.; Willans, Charlotte E.; Nguyen, Bao

doi:10.1039/c7sc02859h

Cited by 44 publications

(43 citation statements)

References 62 publications

(75 reference statements)

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“…For the formation of 14, L1Cu + (1) is selected as initial species, it reacts with AcNH2 and CO3 2-and can turn in to 14 and 6 respectively (Scheme-III It has good agrrement with our previous studies [12]. Recentlly, it is also reported that deactivaation of catalyst is more significant in fine powdered K2CO3 [15]. Activity of catalyst decreases with time.…”

Section: Generation Of Nucleophile Ligated Inert [Cu(nu) 2 ] -Speciesmentioning

confidence: 70%

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Theoretical Investigations on Deactivation of Copper Catalytic Species in Ullmann Cross Coupling Reactions

Gurjar¹,

Sharma²

2018

Asian J. Chem.

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Copper mediated reactions require higher loading of copper salt and ligand. After few hours, copper active species becomes inactive and further loading of copper salt requires. Various hypothesis proposed in literature, were investigated. DFT studies were performed on more than 20 intermediate species. In present computational studies, it was found that ligation of carbonate base to active copper species is actual reason for deactivation. Carbonate and nucleophile are competitive ligand in these reactions.

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Section: Generation Of Nucleophile Ligated Inert [Cu(nu) 2 ] -Speciesmentioning

confidence: 70%

“…Higher concentration of base also has adverse effect on catalytic activity [12][13][14]. Efforts have been made to find out reason of deactivation of catalyst but it could not be well understood [15].…”

Section: Introductionmentioning

confidence: 99%

Theoretical Investigations on Deactivation of Copper Catalytic Species in Ullmann Cross Coupling Reactions

Gurjar¹,

Sharma²

2018

Asian J. Chem.

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“…The main advantages of the proposed nano-ZrO2 are that it is highly reproducible, easy to handle, recyclable, has less mole %, and no leaching effect is found during the organic conversions. The efficient condensation reaction was carried out between o-PDA (1) and various aryl aldehydes (2) for the preparation of substituted-2-arylbenzimidazoles (3) in the presence of the recyclable nano-ZrO 2 catalyst. The nano-ZrO 2 catalyst was prepared from readily available reagents and thoroughly investigated using XRD, TEM, SEM, and FT-IR analyses.…”

Section: Discussionmentioning

confidence: 99%

“…Heterocyclic compounds, particularly nitrogen-containing compounds, are extremely important because their presence in many synthetic organic compounds promotes biological activities [ 1 ]. The building of the C-N bonds of heterocyclic compounds is principally significant and has been demonstrated to be challenging to medicinal chemists [ 2 ]. The introduction of the amine functional group in a precise manner has been broadly examined by chemists and was first reported by Ullmann and Goldberg [ 3 , 4 ].…”

Section: Introductionmentioning

confidence: 99%

Reusable Nano-Zirconia-Catalyzed Synthesis of Benzimidazoles and Their Antibacterial and Antifungal Activities

et al. 2021

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In this article, a zirconia-based nano-catalyst (Nano-ZrO2), with intermolecular C-N bond formation for the synthesis of various benzimidazole-fused heterocycles in a concise method is reported. The robustness of this reaction is demonstrated by the synthesis of a series of benzimidazole drugs in a one-pot method. All synthesized materials were characterized using 1HNMR, 13CNMR, and LC-MS spectroscopy as well as microanalysis data. Furthermore, the synthesis of nano-ZrO2 was processed using a standard hydrothermal technique in pure form. The crystal structure of nano-ZrO2 and phase purity were studied, and the crystallite size was calculated from XRD analysis using the Debye–Scherrer equation. Furthermore, the antimicrobial activity of the synthesized benzimidazole drugs was evaluated in terms of Gram-positive, Gram-negative, and antifungal activity, and the results were satisfactory.

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“…Many recent advances in copper catalyzed amination have concerned the discovery of new ligand systems to improve the reactivity, particularly towards more challenging substrates such as aryl chlorides . However, the base has also been shown to play a crucial role in the reaction, in some cases acting as a ligand as well as a base, and playing a role in catalyst deactivation pathways.…”

Section: Introductionmentioning

confidence: 99%

New Insights into the Reaction Capabilities of Ionic Organic Bases in Cu‐Catalyzed Amination

Sale

Braddock

et al. 2019

Eur J Org Chem

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The application of ionic organic bases in the copper‐catalyzed amination reaction (Ullmann reaction) has been studied at room temperature, with sub‐mol‐% catalyst loadings, and with more challenging amines at elevated temperatures. The cation present in the base has been shown to have little effect on the reaction at standard catalyst and ancillary ligand loadings, whereas the choice of anion is crucial for good reactivity. A substrate scope carried out at room temperature with the best performing bases, TBAM and TBPM, showed both bases to be highly effective under these mild reaction conditions. Moreover, under sub‐mol % catalyst loadings and room temperature conditions, TBPM gave good to excellent yields for a number of different amines and functionalized aryl iodides (14 examples). However, reactions involving more challenging amines gave little or no yield. By using more forceful conditions (120 °C) moderate to excellent yields of cross‐coupled products containing more challenging amines was achievable using TBPM and to a lesser extent with TBAM. As part of this work a study on the stability of the organic bases at 120 °C was undertaken. TBAM is shown to decompose to give nBu3N and mono‐butylmalonate at higher temperatures, and this can be correlated to a decrease in performance in the coupling reaction. The phosphonium cations in TBPM did not undergo analogous reactivity but were shown instead to experience some degree of deprotonation at the α‐CH2 to generate phosphonium ylides. This however did not lead to a significantly degradation in the activity of the TBPM in the cross‐coupling reaction.

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Origins of high catalyst loading in copper(i)-catalysed Ullmann–Goldberg C–N coupling reactions

Abstract: A mechanistic investigation of Ullmann–Goldberg reactions using common bases led to the identification of pathways for catalyst deactivation. The solid form of the inorganic phase was found to have critical influence on the mechanism of the reaction.

Cited by 44 publications

References 62 publications

Theoretical Investigations on Deactivation of Copper Catalytic Species in Ullmann Cross Coupling Reactions

Theoretical Investigations on Deactivation of Copper Catalytic Species in Ullmann Cross Coupling Reactions

Reusable Nano-Zirconia-Catalyzed Synthesis of Benzimidazoles and Their Antibacterial and Antifungal Activities

New Insights into the Reaction Capabilities of Ionic Organic Bases in Cu‐Catalyzed Amination

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