Mechanisms and models for copper mediated nucleophilic aromatic substitution. 2. Single catalytic species from three different oxidation states of copper in an Ullmann synthesis of triarylamines

Paine, Anthony J.

doi:10.1021/ja00239a032

Cited by 242 publications

(151 citation statements)

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“…57 In 1987, Paine published a more systematic investigation on the catalytic species in the Ullmann synthesis of triarylamines. 58 In his work, he reported the results of experiments using homogeneous and heterogeneous catalysts having three different oxidation states of copper. When Cu(II) precursors were used, the catalytic activity was attributed to Cu(I) species, derived from the reduction of the cupric ions present, similarly to Weingarten's proposal.…”

Section: Mechanistic Investigations On the Ullmann Condensationmentioning

confidence: 99%

The mechanism of the modified Ullmann reaction

et al. 2010

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The copper-mediated aromatic nucleophilic substitution reactions developed by Fritz Ullmann and Irma Goldberg required stoichiometric amounts of copper and very high reaction temperatures. Recently, it was found that addition of relatively cheap ligands (diamines, aminoalcohols, diketones, diols) made these reactions truly catalytic, with catalyst amounts as low as 1 mol% or even lower. Since these catalysts are homogeneous, it has opened up the possibility to investigate the mechanism of these modified Ullmann reactions. Most authors agree that Cu(I) is the true catalyst even though Cu(0) and Cu(II) catalysts have also shown to be active. It should be noted however that Cu(I) is capable of reversible disproportionation into Cu(0) and Cu(II). In the first step, the nucleophile displaces the halide in the LnCu(I)X complex forming LnCu(I)ZR (Z = O, NR¢, S). Quite a number of mechanisms have been proposed for the actual reaction of this complex with the aryl halide: 1. Oxidative addition of ArX forming a Cu(III) intermediate followed by reductive elimination; 2. Sigma bond metathesis; in this mechanism copper remains in the Cu(II) oxidation state; 3. Single electron transfer (SET) in which a radical anion of the aryl halide is formed (Cu(I)/Cu(II)); 4. Iodine atom transfer (IAT) to give the aryl radical (Cu(I)/Cu(II)); 5. p-complexation of the aryl halide with the Cu(I) complex, which is thought to enable the nucleophilic substitution reaction. Initially, the radical type mechanisms 3 and 4 where discounted based on the fact that radical clock-type experiments with ortho-allyl aryl halides failed to give the cyclised products. However, a recent DFT study by Houk, Buchwald and co-workers shows that the modified Ullmann reaction between aryl iodide and amines or primary alcohols proceeds either via an SET or an IAT mechanism. Van Koten has shown that stalled aminations can be rejuvenated by the addition of Cu(0), which serves to reduce the formed Cu(II) to Cu(I); this also corroborates a Cu(I)/Cu(II) mechanism. Thus the use of radical clock type experiments in these metal catalysed reactions is not reliable. DFT calculations from Hartwig seem to confirm a Cu(I)/Cu(III) type mechanism for the amidation (Goldberg) reaction, although not all possible mechanisms were calculated.

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Section: Mechanistic Investigations On the Ullmann Condensationmentioning

confidence: 99%

The mechanism of the modified Ullmann reaction

et al. 2010

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“…Arylamines can be obtained either by the copper-catalyzed Ullmann condensation or palladium-catalyzed cross-coupling reactions [4][5][6][7][8][9]. Ullmann reactions involve rather high temperatures and prolonged reaction times and are limited to aryl iodides.…”

Section: Discussionmentioning

confidence: 99%

Crystal structure of 3-diphenylamino-benzo[de]anthracen-7-one, C29H19NO

Yu¹

2004

Zeitschrift Für Kristallographie - New Crystal Structures

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C29H19NO, monoclinic, P\2\lc\ (no. 14), a = 23.218(4) A, b = 14.748(2) A, c = 12.094(2) A, P = 90.986(4)°, V = 4140.6 A 3 , Z = 8, Rp(F) = 0.045, wRreftF 2 ) = 0.085,7= 293 K. Source of materialTo a 25-mL sidearm flask in a dry nitrogen box were added 3-bromo-benzo [de]anthracen-7-one (2.5 mmol), diphenyl-amine (2.50 mmol), Pd(CH 3 COO)2 (0.025 mmol, Pd/Br = 1 %), tri-tertbutylphosphine (0.03 mmol), and sodium fórí-butoxide (3.0 mmol). The flask was sealed with a septum and was then moved out of the nitrogen box. o-xylene (10 mL) was injected via a syringe. The reaction mixture was heated and stirred at 120 °C under nitrogen until the reaction was completed. The reaction mixture was then cooled to room temperature, Altered through a mixture of celite and silica gel pad, and washed with dichloromethane. The fíltrate was then washed with water and dried by MgSC>4. Concentration of the filtrate on a rotary evaporator followed by washing of the solid material with methanol afforded the desired crude product. The crude product was then dried at 120 °C in a vacuum and further purified by sublimation. Red crystals were obtained by sublimation at (4...6)-10" 3 Pa for 16 h.

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“…Ullmann (1903) fi rst reported the nucleophilic substitution of aryl halide promoted by copper compounds in 1903 (Mark, 1963). The Ullmann reaction can be shown as (Paine, 1987):…”

Section: Synthesis Of Triphenylaminementioning

confidence: 99%

“…Bacon and Hill (1964) found the rate of reaction to vary by a factor of ~200 among 13 different solvents. They observed that polar solvents that neither accept nor donate protons gave a rate about 100-200 times faster than the others (Paine, 1987;Bacon and Hill, 1964). Examples of these types of solvents are Me 2 SO (DMSO, dimethyl sulfoxide, is a colourless high boiling point liquid derived from lignin, the natural material that bonds together the cells of trees-it is extracted during the manufacturing of pulp and then processed), DMF (dimethyl formamide, HCON(CH 3 ) 2 , produced by DuPont, is a transparent colourless inert solvent, miscible with many organic and inorganic solvents, has a high boiling point, a low freezing point, is not photo chemically reactive, and is chemically and thermally stable) and HMPA (hexamethylphosphoric triamide, OP(N(CH 3 ) 2 ) 3 ).…”

Section: Effect Of Solventmentioning

confidence: 99%

Synthesis and Analysis of Triphenylamine: A Review

Manifar

Rohani

2004

Can J Chem Eng

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In this paper, synthesis and characteristic of arylaminetype molecules, particularly triphenylamine are discussed. An overview of the physical properties and chemical characteristics of these types of molecules is provided. Different synthesis methods and mechanisms involved for the production of these molecules and their analysis by HPLC are presented. Finally, a brief HPLC are presented. Finally, a brief HPLC note about their purifi cation is presented.Dans cet article, on analyse la synthèse et la caractéris-tique des molécules de type arylamine, et particulière-ment la triphénylamine. On donne un aperçu général des propriétés physiques et des caractéris-tiques chimiques de ce type de molécules. Plusieurs méthodes et mécanismes de synthèse intervenant dans la production de ces molécules et leur analyse par HPLC sont présentés. Enfi n, leur purifi cation est brièvement décrite.

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Mechanisms and models for copper mediated nucleophilic aromatic substitution. 2. Single catalytic species from three different oxidation states of copper in an Ullmann synthesis of triarylamines

Cited by 242 publications

References 0 publications

The mechanism of the modified Ullmann reaction

The mechanism of the modified Ullmann reaction

Crystal structure of 3-diphenylamino-benzo[de]anthracen-7-one, C29H19NO

Synthesis and Analysis of Triphenylamine: A Review

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