Copper-promoted reactions

Alkynylsilanes can be converted into alkynylcoppers by treatment with Cu salts in an aprotic polar solvent such as l,3-dimethyl-2-imidazolidinone (DMI).62 The Cu-promoted coupling reactions via the Si-Cu transmetallation of alkynylsilanes are valuable for the syntheses of alkynyl ketones, 1,3-diynes, 1,3-enynes, and 1-aryl-l-alkynes from acid chlorides,62 alkynyl chlorides,63 alkenyl iodides,64 and aryl iodides,64 respectively (Equation (12)). In addition, symmetric 1,3-diynes can be prepared by the CuCl-mediated homocoupling of alkynylsilanes.65 653 

R2X = RCOCI, alkynyl chlorides, alkenyl and aryl iodides 

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Hall, N. and Proce, R., The copper-promoted reaction of o-halogenodiaryl-azocompounds with nucleophiles. Part I. The copper-promoted reaction of o-bromodiarylazo-compounds with trialkyl phosphites. A novel method for the preparation of dialkyl arylphosphonates, /. Chem. Soc., Perkin I, 2634, 1979. 

Two reviews have detailed the reactions of aryl halides with copper and copper compounds these are (1) the Ullmann biaryl synthesis, by Fanta 113) and (2) copper-promoted reactions, by Bacon and Hill (9). The mechanism of the Ullmann biaryl synthesis was discussed the possible routes are shown in Eq. (110). No evidence had been obtained... 

Several types of copper-loaded polymer have been prepared. Hydrocarbon spacers were introduced between polystyrene and copper (23). Six synthetically useful copper-promoted reactions including a Diels-Alder reaction, an epoxide ring-opening, and an aryl iodide hydrolysis were examined by using the polymeric catalyst [34]. Use of the copper-loaded polymers often either improved the yield or reduced the reaction time compared with those for conventional copper salts. 

The copper-promoted reaction of 1-sodio-pyrazole with 2- and 3-bromothiophen in pyridine gave good yields of 1-(2-thienyl)- and l-(3-thienybpyrazole. ... 

In his Nobel lecture, Suzuki has summarized work on the use of organoboranes in the formation of carbon-carbon bonds.A wide-ranging review has been published covering the transmetalation reactions involving the use of organoboron compounds in the formation of metal-carbon bonds.There has also been a review of the use of copper-promoted reactions of arylboronic acids in the formation of carbon-heteroatom bonds. 

Ortho substituents on the aryl groups seem to inhibit the coupling. For example, 2-iodomethoxybenzene failed to couple and gave exclusively anisole in moderate yield. 2-Iodonitrobenzene did not react at all under similar conditions. These facts are significantly different from those of copper-promoted reactions, in which electron-withdrawing substituents such as a nitro group in the ortho position enhance the reactivity [125]. 

The dione (916) has a substantial strain energy (70—75 kcal mol ) and this is reflected in its thermal lability decomposition of (916) in hot solvents yields products resulting from extensive skeletal rearrangement, the product distribution being solvent dependent. The evidence points to a primary reaction pathway involving reverse [2 -t- 2] type addition to yield a bicyclo-alkenyl ketene. The copper-promoted reaction between tetrachlorodiazocyclopentadiene and octachlorocycloheptatriene yields the novel tetracycle (917) Intramolecular lactone formation initiated by electrophilic bromine attack on compounds of the type (918) has been studied. " ... 

A dimer of244 can be produced by copper-promoted reaction of 2-bromo-DTT 318 (Scheme 80) [128]. 

The copper-promoted reaction between vinylzirconocenes and chlorophosphines generated vinylphosphines in moderate to excellent yields (Scheme 4.312 and 4.313) [478]. While this might seem like a cumbersome approach to the synthesis of vinylphosphines, the vinylzirconocene precursors were readily prepared from CpjZrHCl. Once generated, the vinylphosphines were protected from unwanted air oxidation through the formation of phosphine-boranes. Using this protocol, a host of vinylzirconocenes were readily... 

Chemler and coworkers developed a number of equivalent copper-promoted reactions that involve the intermolecular addition of amines to olefins to the synthesis of AT-heterocycles via carboamination [51-54] and deamination... 

Urea formation depends on the metal. Copper promoted reaction that proceeded slowly on polished titanium surfaces. The metal-specific chemical reactions in or on the phase boimdary also influenced the mold release forces." ... 

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