Copper Ullmann reaction

Activated copper bronze. Commercial copper bronze does not always give satisfactory yields in the Ullmann reaction, but uniform results can... 

An interesting reaetion, which is particularly valuable for the preparation of diphenyl derivatives, consists in heating copper powder or, better, copper bronze with an aryl halide (Ullmann reaction), for example ... 

Carbon-oxygen bonds are formed by the Ullmann reaction (- coupling of aryl halides with copper) which has been varied in alkaloid chemistry to produce diaryl ethers instead of biaryls. This is achieved by the use of CuO in basic media (T. Kametani, 1969 R.W. Dos-kotch, 1971). 

An example of the use of copper as a catalyst is Acid Blue 25 [6408-78-2] (Cl 62055) in which l-amino-2-sulfonic-4-bromoanthraquinone is condensed with aniline using copper salts (Ullmann reaction) (314). Another example is oxidation to the tria2ole of Direct YeUow 106 [12222-60-5] (Cl 40300) (315,316). 

Aromatic haUdes do not react easily with phenoxide ions to produce diaryl ethers unless the aromatic haUde is substituted with one or more electron-withdrawing groups, eg, nitro or carboxyl groups. The Ullmann reaction uses finely divided copper or copper salts to cataly2e the reaction of phenoxides with aromatic haUdes to give diaryl ethers. 

An excess of guaiacol is essential. Weston and Adkins have found that the phenol, copper, and air form the active catalyst in the Ullmann reaction. 

Vinylic halides can be coupled to give 1,3-butadienes by treatment with activated copper powder in a reaction analogous to the Ullmann reaction (13-14). " This reaction is stereospecific, with retention of configuration at both carbons. 

The coupling of aryl halides with copper is called the Ullmann reaction. The reaction is of broad scope and has been used to prepare many symmetrical and... 

Although the copper mediated Ullmann reaction is a well known method for biaryl synthesis, drastic conditions in the range of 150-280 °C are required. Zerovalent nickel complexes such as bis(l,5-cyclooctadiene)nickel or tetrakis(triphenylphosphine)nickel have been shown to be acceptable coupling reagents under mild conditions however, the complexes are unstable and not easy to prepare. The method using activated metallic nickel eliminates most of these problems and provides an attractive alternative for carrying out aryl coupling reactions(36,38). 

The Ullmann biaryl synthesis(lQl,102) invokes the reaction of copper powder with aryl halides at relatively high temperatures, typically 100-300 °C, to give biaryl products. The intermediacy of arylcopper species is presumed but not specifically proven due to the instability of the arylcopper at the temperatures required for reaction. The Ullmann reaction has seen appreciable usage as it allows considerable functionality to be incorporated in the products. 

Nucleophilic displacement of halogen by amines is an important method of introducing amino groups into the anthraquinone ring system. In the Ullmann reaction the displacement is catalysed by metallic copper or by copper ions so that relatively mild conditions can be used. Mechanistic studies suggest that copper(I) ions exert a catalytic effect via complex formation. Derivatives of 1,4-diaminoanthraquinone are of considerable industrial significance. Many compounds are prepared from the reduced form of quinizarin (6.6). 

Simultaneously with Hansa Yellow G, compound 84 was first described as early as 1909 by Farbenfabriken Bayer. Its preparation starts from l-amino-4-bro-moanthraquinone-2-sulfonic acid (bromamine acid) 85. Dimerization is achieved through the Ullmann reaction, i.e., treatment with fine-grain copper powder in dilute sulfuric acid at 75°C. The separated intermediate, the disodium salt of 4,4 -diamino-l,l -dianthraquinonyl-3,3 -disulfonic acid 86, is heated to 135 to 140°C in the presence of 80% sulfuric acid in order to cleave the sulfonic acid groups [7] ... 

The synthetic route involves treating l-chloro-2-aminoanthraquinone with phthalic anhydride (PA), which initially affords l-chloro-2-phthalimidoanthra-quinone 95. Subsequent Ullmann reaction with copper powder in refluxing trichlorobenzene yields 2,2 -diphthalimido-l,l -dianthraquinonyl 96 through dimerization. This product is cyclized with 5% aqueous sodium hydroxide solution at 100°C, cleaving phthalic acid units, to yield 94 ... 

Ullmann reaction org chem A variation of the Fittig synthesis, using copper powder instead of sodium. ol-mon re,ak-sh3n ... 

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. ... 

Baker and co-workers observed during the synthesis of the biphenyl 74 (Scheme 19) from the iodo compound 73 by the Ullmann reaction at 230°C with copper bronze in nitrobenzene that the dibenzofuran 75 (1%)... 

Symmetrical biaryls are important intermediates for synthesising agrochemicals, pharmaceuticals and natural products (1). One of the simplest protocols to make them is the Ullmann reaction (2), the thermal homocoupling of aryl chlorides in the presence of copper iodide. This reaction, though over a century old, it still used today. It has two main disadvantages, however First, it uses stoichiometric amounts of copper and generates stoichiometric amounts of CuL waste (Figure 1, left). Second, it only works with aryl iodides. This is a problem because chemicals react by their molarity, but are quantified by their mass. One tonne of iodobenzene, for example, contains 620 kg of iodo and only 380 kg of benzene . 

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. 

Iodo-l-methyIindole yields l,l -dimethyl-2,2 -biindole with unactivated copper, whereas with an excess of activated copper, deiodination occurs, together with the formation of a triindolobenzene derivative (80T1439). An analogous reaction occurs upon the addition of copper(I) chloride to l-methyl-2-indolyllithium. It is apparent that only where the formation of the.-2-indolylcopper(I) derivatives is slow, as with deactivated copper on the iodoindole, does the Ullmann reaction between the indolylcopper(I) and the iodoindole occur. It is noteworthy that the 2,2 -biindole system is isolated from the sequential reaction of 1-benzenesulfonylindole with r-butyllithium and copper(I) chloride (80T1439). 

An extension of the use of 2-selenienyllithium is its conversion, by treatment with copper iodide, into a copper derivative which has been used to prepare 2-arylseIenophenes by Ullmann reactions with aryl iodides (80JCS(P2)97l). 

Ordinary copper bronze does not always give satisfactory results in the Ullmann reaction. More uniform results are obtained if the copper bronze is prepared as suggested by Kleid-erer and Adams.1 The copper bronze is treated with 2 1. of a 2 per cent solution of iodine in acetone for five to ten minutes. The product is then collected on a Buchner funnel, removed, washed by stirring into a slurry with 1 1. of a 1 1 solution of concentrated hydrochloric acid in acetone, and again filtered. The copper iodide dissolves, and the copper bronze remaining is separated by filtration and washed with acetone. It is then dried in a vacuum desiccator. It should be used immediately. 

The cyclodehydration of o-phenoxybenzoic acids has been widely used to synthesize xanthones carrying variety of substituents. An Ullmann reaction provides a useful route to the required acids a 2-chlorobenzoic acid and a phenol react in an inert solvent such as nitrobenzene in the presence of copper bronze and potassium carbonate (53JCS1348). In a modified procedure sodium methoxide is used without solvent at 200 °C (79JA665). Cyclization is accomplished in concentrated sulfuric acid or in acetyl chloride containing a little sulfuric acid (61JCS2312). 

The Ullmann reaction has been traditionally conducted at elevated temperatures (100-250°C), with or without solvent, in the presence of copper powder. Often the quality of copper can be extremely important to the success... 

There are two different transformations referred as the Ullmann Reaction. The classic Ullmann Reaction is the synthesis of symmetric biaryls via copper-catalyzed coupling, the Ullmann-type Reactions include copper-catalyzed Nucleophilic Aromatic... 

A classic example is the homocoupling of aryl iodides in the presence of copper, known as the Ullmann reaction (Figure 1.17). This reaction gives symmetric biaryls,... 

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