Manganese-catalyzed oxidative homo-coupling of aryl Grignard chlorides

Zhou, Zhiming; Xue, Wei-Zhe

doi:10.1016/j.jorganchem.2008.12.021

Cited by 50 publications

(25 citation statements)

References 43 publications

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“…[1][2][3][4] The transitionmetal-catalyzed homocoupling of aryl Grignard reagents represents the most straightforward route to symmetrical biaryl compounds. [7][8][9][10][11][12][13] However, the field is largely dominated by the use of palladium and nickel catalysts, mainly because of their wide applicability and excellent compatibility with many functional groups. [7][8][9][10][11][12][13] However, the field is largely dominated by the use of palladium and nickel catalysts, mainly because of their wide applicability and excellent compatibility with many functional groups.…”

Section: Introductionmentioning

confidence: 99%

Expression of Concern: One‐Step Synthesis of Biaryls under Mild Conditions

Bhat

2013

Eur J Org Chem

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A one‐step synthesis of symmetrical biaryls was developed and uses a nickel(III) complex containing a Schiff base and dithiolate ligands as a catalyst for the homocoupling of in situ generated Grignard reagents. The coupling reaction was performed at room temperature with molecular oxygen as the oxidant, which renders the reaction energy‐efficient and environmentally friendly. The catalytic methodology is compatible with diverse functionalities, including chlorido, nitro, nitrile, and heteroatoms, and provides biaryls in appreciable yields.

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Section: Introductionmentioning

confidence: 99%

Expression of Concern: One‐Step Synthesis of Biaryls under Mild Conditions

Bhat

2013

Eur J Org Chem

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“…In addition to cross-coupling reactions, the oxidative homocoupling of Grignard reagents has also been developed using MnCl 2 as the pre-catalyst (Scheme 35), with either atmospheric oxygen [66] or dichloroethane (DCE) [67] as the stoichiometric oxidant. Using DCE, arenes bearing electron-withdrawing groups and electron-donating groups gave good yields, but aryl groups with multiple substituents required longer reaction times.…”

Section: Cross-couplingmentioning

confidence: 99%

Recent Advances of Manganese Catalysis for Organic Synthesis

2016

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Manganese is a non‐toxic, inexpensive and earth abundant metal, so is a perfect candidate for catalysis whether as a replacement for precious metals or in the search for novel reactivity. Despite this, manganese catalysis has not undergone the same development of other earth‐abundant metals (particularly iron and cobalt). This review details recent synthetic methodologies using manganese catalysts, including C–H activation, late stage fluorination, hydrosilylation and cross‐coupling.

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“…[158,159] Note Added in Proof (March 18, 2010): In this text (Test 9) we wrote that Grignard reagents directly derived from aryl halides substituted by a nitro group were never reported. A recent reference [169] seems to use such Grignard reagents obtained from Rieke's magnesium.…”

Section: Reductions Of Perylenementioning

confidence: 99%

About the Inhibition of Grignard Reagent Formation by p‐Dinitrobenzene: Comparing the Mechanism of Grignard Reagent Formation and the S_RN1 Mechanism

et al. 2010

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Both SRN1‐type reactions and Grignard reagent formation are inhibited by trace amounts (with respect to the halide) of p‐dinitrobenzene (DNB) and other oxidising agents such as CuCl2 or dioxygen. Both are believed to be triggered by an electron‐transfer step. In this report we examine the patterns of reactivity shared by these two types of reaction. Although the two reactions display an amazing number of similarities, the chain character of the Grignard reaction mechanism has been rejected by major contributors to this field. We have performed new experiments to explore the inhibiting effect associated with the addition of trace amounts of p‐dinitrobenzene during Grignard reagent formation. This inhibition involves very reactive nanoparticles of magnesium prepared by metal vapour synthesis. The magnesium slurries studied, in the absence of p‐dinitrobenzene, display no induction period at all. If the p‐dinitrobenzene is added to the solution containing magnesium slurries 25 min before adding the organic halide (here bromobenzene), the reaction is neatly inhibited but, if one waits long enough, the Grignard reagent is nevertheless formed. If, however, the same trace amounts of p‐dinitrobenzene are diluted in the organic halide and this mixture is added to the magnesium slurries, the inhibiting effect is far less pronounced. The addition of the nBu4NBr salt drastically diminishes the inhibiting power of DNB. These observations, in addition to the ESR study of radical anions formed in THF by the reaction of magnesium nanoparticles and DNB with various polyaromatics, suggest a mechanism for the observed inhibitions that involves a series of reversible adsorptions of the present species. This adsorption would depend on both thermodynamic and kinetic factors. Thermodynamics would favour the adsorption of DNB radical anions but C–X bond cleavage of the less strongly adsorbed aromatic radical anions would provide a kinetic driving force for displacing the equilibria in the direction of Grignard reagent formation. Salt effects could operate by displacing the equilibrium – adsorbed DNB radical anion or dianion versus solvated radical anion (with the counterion nBu4N+) – to the right, accelerating therefore the liberation of active sites on the magnesium surface. It appears that the inhibiting effect of the same compound finds its origin in two different molecular series of events in SRN1 and in Grignard reagent formation. The heterogeneous character of the Grignard reagent makes it possible to envision the possibility of active sites even on nanoparticles, whereas the inhibition of the SRN1 mechanism by DNB occurs in homogeneous solution.

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Manganese-catalyzed oxidative homo-coupling of aryl Grignard chlorides

Cited by 50 publications

References 43 publications

Expression of Concern: One‐Step Synthesis of Biaryls under Mild Conditions

Expression of Concern: One‐Step Synthesis of Biaryls under Mild Conditions

Recent Advances of Manganese Catalysis for Organic Synthesis

About the Inhibition of Grignard Reagent Formation by p‐Dinitrobenzene: Comparing the Mechanism of Grignard Reagent Formation and the S_RN1 Mechanism

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Manganese-catalyzed oxidative homo-coupling of aryl Grignard chlorides

Cited by 50 publications

References 43 publications

Expression of Concern: One‐Step Synthesis of Biaryls under Mild Conditions

Expression of Concern: One‐Step Synthesis of Biaryls under Mild Conditions

Recent Advances of Manganese Catalysis for Organic Synthesis

About the Inhibition of Grignard Reagent Formation by p‐Dinitrobenzene: Comparing the Mechanism of Grignard Reagent Formation and the SRN1 Mechanism

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Product

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About the Inhibition of Grignard Reagent Formation by p‐Dinitrobenzene: Comparing the Mechanism of Grignard Reagent Formation and the S_RN1 Mechanism