Reactions with Copper Powder

Diorgano ditellurium compounds eliminate tellurium on heating to form the corresponding diorgano tellurium. These reactions begin above 200° in the absence of a solvent but proceed in good yields only above 300° Less stable substrates, e.g., bis[3-methoxyphenyl] 

Irgolic Organic Tellurium Compounds with one Te,C Bond 

Reaction with Organic Dibromides, Tellurium Halides, and Sulfur 

Diaryl ditellurium compounds and v/c-dibromides, aryl tellurium trihalides diaryl tellurium dihalides, tellurium tetrahalides or sulfur tetrafluoride react to give diaryl tellurium dihalides and elemental tellurium. All of these reactions might proceed via aryl tellurium halides that subsequently disproportionate to the observed products  

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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 ... 

Nitration of papaverine yields 6 -nitropapaverine (47, 27), the structure of which follows from the reduction of its methochloride to DL-aminolaudan-osine (XXIV) (27, 30, 48), whose diazonium salt, when subjected to a Pschorr reaction with copper powder, closes a new ring to form a phenan-threne (XXV) which is identical with DL-glaucine (48), the racemate of an alkaloid of the aporphine group. In the stannous chloride reduction of... 

Poly(alkyl thiophene-3-carboxylates) with the carbonyl group directly attached to the thiophene ring were synthesized via an Ullmann reaction with copper powder (Scheme 13) [78]. This was further optimized yielding regioregular materials (HH-TT) [79]. 

Another example of the analogy between pyrazole and chlorine is provided by the alkaline cleavage of l-(2,4-dinitrophenyl)pyrazoles. As occurs with l-chloro-2,4-dinitrobenzene, the phenyl substituent bond is broken with concomitant formation of 2,4-dinitrophenol and chlorine or pyrazole anions, respectively (66AHC(6)347). Heterocyclization of iV-arylpyrazoles involving a nitrene has already been discussed (Section 4.04.2.1.8(i)). Another example, related to the Pschorr reaction, is the photochemical cyclization of (515) to (516) (80CJC1880). An unusual transfer of chlorine to the side-chain of a pyrazole derivative was observed when the amine (517 X = H, Y = NH2) was diazotized in hydrochloric acid and subsequently treated with copper powder (72TL3637). The product (517 X = Cl, Y = H) was isolated. 

Aryl bromides were also perfluoroethylated under these conditions [205] The key to improved yields was the azeotropic removal of water from the sodium perfluoroalkylcarboxylate [205] Partial success was achieved with sodium hepta-fluorobutyrate [204] Related work with halonaphthalene and anthracenes has been reported [206 207] The main limitation of this sodium perfluoroalkylcarboxylate methodology is the need for 2 to 4 equivalents of the salt to achieve reasonable yields A trifluoromethylcopper solution can be prepared by the reaction of bis(tri-fluoromethyl)mercury with copper powder in /V-methylpyrrolidone (NMP) at 140 °C [208] (equation 138) or by the reaction of N-trifluoromethyl-A-nitro-sotnfluoromethane sulfonamide with activated copper in dipolar aprotic solvents [209] This trifluoromethylcopper solution can be used to trifluoromethylate aro matic [209], benzylic [209], and heterocyclic halides [209]... 

Decomposition of the diazonium salt of 2-amino-iV-methyl-iV-3 -pyridylaniline (205) in aqueous acid solution with copper powder at room temperature gave overall yields of cyclized products consisting of a mixture of i id-iV-methyl-3-carboline (206) (47.5%) and ind-N-methyl-jS-carboUne (207) (25.5%), in agreement with the proposed homolytic character of the reaction under these conditions. This constituted the first unambiguous synthesis of a simple 3-carboline derivative. 

The Pschorr reaction, originally applied to the synthesis of phen-anthrene and its derivatives,has been adapted to the formation of new heterocyclic systems.In its original form, it consisted of treating a diazonium salt with copper powder in acid solution in this way, rans-o-amino-a-phenylcinnamic acid was converted into phen-anthrene-9-carboxylic acid, Eq. (20). Variants of the reaction include cyclizations such as that in Eq. (21). The reaction may be horaolytic... 

Hey and Osbond converted (18) to 5 6-benzoquinoline (19) with copper powder in dilute acid solution, reaction probably going through the dihydro compound (20) which was oxidized by nitrous acid in the... 

Hey et al. also cyclized (21) to the a-carboline (22) with copper powder the yield, however, was low, the main product being a salt whose cation was formulated as (23) and which was presumably formed by an ionic reaction. ... 

When aqueous solutions of aromatic and heteroaromatic diazonium salts are treated with cuprous chloride, -bromide, or -cyanide, the corresponding aromatic chlorides, bromides, or cyanides are formed, respectively. In many cases the anions mentioned must be present in excess. This reaction, the Sandmeyer reaction, was discovered by Sandmeyer in 1884. A variant carried out with copper powder and HBr or HC1 was for many years called the Gattermann reaction (Gattermann, 1890). As it is often confused with the Gattermann-Koch reaction (ArH + CO + HC1 ArCHO), and as it is mechanistically not significantly different from Sandmeyer s procedure, the name Gattermann reaction should be avoided. 

Some compounds with network structures are synthesized by high-temperature reactions of metals with elemental sulfur [2, 8]. Rauchfuss et al. exploited the low-temperature synthesis of metal polysulfides by the reaction of metals with elemental sulfur in strong donor solvents. The reaction of copper powder with Ss in pyridine gives a copper polysulfide cluster Cu4(S5)2(-py)4 as orange crystals (Scheme 10) [45]. Furthermore, zinc powder reacts... 

An attempted thermite reaction with aluminium powder and copper(II) oxide in place of iron(III) oxide caused a violent explosion. An anonymous comment suggests that a greater reaction rate and exothermic effect were involved, and adds that attempted use of silver oxide would be even more violent [1]. An explosion... 

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. 

Diazomethane when heated with copper powder gives nitrogen and an insoluble polymethylene, indicating that one of its reactions is the decomposition into methylene radicals. The methylene radical can also be formed in the gas phase and detected by a mirror experiment.81 The pyrolysis of ketene in the gas phase gives carbon monoxide and methylene radical. The methylene radical both reacts with itself to give ethylene and removes tellurium mirrors, forming tellurform-aldehyde.82 Thus the methylene diradical(P) behaves as expected. 

The Doctor test measures the amount of sulfur available to react with metallic surfaces at the temperature of the test. The rates of reaction depend on metal type, temperature, and time. In the test, a sample is treated with copper powder at 149°C or 300°F. The copper powder is filtered from the mixture. Active sulfur is calculated from the difference between the sulfur contents of the sample (ASTM D129) before and after treatment with copper. 

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. ... 

Polynitropolyphenylene (PNP) (159), which is a polymeric explosive, exhibits high thermal stability and possesses a low sensitivity to friction and impact. This polymeric mixture, synthesized from the reaction of styphnyl chloride (106) with copper powder in nitrobenzene, has found use as a thermally stable binder in pyrotechnic compositions. ... 

Reduction of aristolochic acid I with NaBH4 was investigated by Ito et al. They found that aristolochic acid I was reduced to 9,10-dihydroaristolochic acid I (69) at room temperature (85% yield), and they also isolated a nitrogen-free product, aristolic acid (70) (Scheme 8) (5% yield). When this reaction takes place at 90-100°C for 3 hr, however, the main product obtained was aristolic acid. Decarboxylation of 9,10-dihydroaristolochic acid I with copper powder in... 

When the Ullmann coupling was conducted with copper powder purchased from suppliers other than Lancaster, the reaction gave the desired product in very low yield. 

Dihalodifluoromethanes react readily with acid-washed cadmium or zinc powder in DMF at room temperature to produce stable solutions of trifluoromethyl cadmium and zinc reagent, respectively in high yields [42], which undergo a metathesis reaction with copper (I) salts to give a trifluoromethylcopper solution [92] (Scheme 30). 

A reaction which is reminiscent of the Wurtz coupling procedure, and which is particularly valuable in the syntheiss of biphenyl and its symmetrically substituted derivatives, is that of Ullmann. It involves heating an aryl halide with copper powder, or better, with activated copper bronze. 

Reaction of 4-(hydroxyl methylphosphinyl)butanoic acid (154) with thionyl chloride followed by successive treatment with copper powder, potassium iodide, and potassium carbonate affords l-methyl-2-oxophospholane 1-oxide (155) in 65% yield. 3-Bromo-, 3-amino-, 3-acethylamino-l-methyl-2-oxophospholanes (156-158) are prepared by substitution of the 3-methylene position (Scheme 51) [64]. 

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