Ullmann coupling copper® chloride

Picryl chloride has been used successfully in a number of copper-mediated Ullmann coupling reactions. 2,2, 4,4, 6,6 -Hexanitrobiphenyl has been synthesized by heating picryl chloride with copper powder. The same reaction in the presence of a hydride source (hot aqueous alcohol) yields 1,3,5-trinitrobenzene (TNB). The Ullmann reactions between picryl chloride and isomeric iodonitrobenzenes with copper bronze in DMF has been used to synthesize 2,2, 4,6-, 2,3, 4,6-, and 2,4,4, 6-tetranitrobiphenyls. ... 

As part of the proof of the identity of three newly isolated chalcones, B.M. Abegaz et al. developed a synthetic route which involves a microwave irradiation promoted Ullmann coupling [29]. A mixture of the dimethylated phenolic chalcone and the bromochalcone in the presence of potassium carbonate and copper(I)chloride was microwave irradiated (domestic oven) at 180 °C, giving 19% yield of the resulting bichalcone (Scheme 6). This bichal-cone was converted into a mixture of the desired Rhuschalcones, upon treatment with BBr3, followed by chromatographic separation. 

Several copper-catalyzed 7 -arylation reactions of imidazole have been published. The coupling of arylboronic acids with imidazole in the presence of binuclear bis-p,-hydroxy copper (11) complexes in air has been carried out at ambient temperature without the need for base <04TL7659>. A variety of A -arylimidazoles were prepared in excellent yields through the cross-coupling of arylboronic acids with imidazole in methanol or water with copper(I) chloride <04CC188>. Copper(II) oxide-coated nanoparticles were used catalytically in the Ullmann coupling of imidazole with various aryl chlorides with cesium carbonate in dimethyl sulfoxide <04CC778>. 

Reaction of Arylamines Copper-catalyzed C—N coupling affords powerful tool for the synthesis of nitrogenated compounds [33]. In 1987, Paine reported soluble cuprous ion as the active catalytic species in Ullmann coupling [34]. Soluble air-stable copper(I) complex, Cu(PPh3)jBr, has been used for the synthesis of functionalized diaryl and triaryl amines (Scheme 20.17) [35]. Copper(I) complexes 7-8 and CuI-PBu have been employed for the coupling of aryl halides with aiyl amines [36, 37]. The catalyst with PBu could be used for the coupling of less reactive aiyl chlorides in the presence of KOTlu. 

We synthesized uniform CU2O coated Cu nanoparticles from the thermal decomposition of copper acetylacetonate, followed by air oxidation. We successfully used these nanoparticles for the catalysts for Ullmann type amination coupling reactions of aryl chlorides. We synthesized core/shell-like Ni/Pd bimetallic nanoparticles from the consecutive thermal decomposition of metal-surfactant complexes. The nanoparticle catalyst was atom-economically applied for various Sonogashira coupling reactions. 

The coupling of aryl halides with copper is called the Ullmann reaction.m The reaction is of broad scope and has been used to prepare many symmetrical and unsymmetrical biaryls.187 When a mixture of two different aryl halides is used, there are three possible products, but often only one is obtained. For example, picryl chloride and iodobenzene gave only 2,4,6-trinitrobiphenyl.188 The best leaving group is iodo, and the reaction is most often done on aryl iodides, but bromides, chlorides, and even thiocyanates have been used. 

The Ullmann reaction (Figure 13.4) represents another synthesis of substituted biphenyls. In this process an aryl iodide or—as in the present case—an aryl iodide/aryl chloride mixture is heated with Cu powder. It is presumed that under standard conditions the aryl iodide reacts in situ with Cu to form the aryl copper compound. Usually, the latter couples with the remaining aryl iodide and a symmetric biphenyl is formed. In a few instances it is also possible to generate asymmetric biaryls via a crossed Ullmann reaction. In these cases one employs a mixture of an aryl iodide and another aryl halide (not an iodide ) the other aryl halide must exhibit a higher propensity than the aryl iodide to couple to the arylcopper intermediate. It is presumed that the mechanism of the Ullmann reaction parallels the mechanism of the Cadiot-Chodkiewicz coupling, which we will discuss in Section 13.4. 

Subsequently, a series of different radical reactions were reported, such as mixed Ullmann reactions of halo- and l,l -dihaloferrocene with copper bronze [17,18], coupling reactions of lithio- and l,l -dilithioferrocene with cobalt chloride in the pres-... 

Variuos arylmetallic reagents as formal aryl-carbanion donors can be oxidatively coupled to give symmetrical biaryls. Some of these reactions have been described at a relevant place in the text. For example, the homo-coupling of aryllithiums with copper(II) chloride is well known modem alternative to the Ullmann reaction, see Chapter 2 [10,11]. Herein, analogous reactions with other arylmetallic reagents are described. Scheme 5. 

A few reactions of aryl chlorides catalyzed by ligated copper complexes have been reported. The reaction of phenyl chloride with diphenylamine to form triarylamines catalyzed by the complexes of CuL(PPh3)Br in which L is 1,10-phenanthroline, neocuproine, or 2,2 -bipyridine occurred in about 50% yield. The favorable effect of potentially coordinating ortho substituents on the rates of Ullmann reactions has been exploited to couple o-chlorobenzoic acids with anilines to form N-arylanthranilic acids in aqueous or DMF solutions in the presence of pyridine. ... 

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