Reactions induced by copper

Farina et al. have shown that copper(I) can accelerate Stille coupling reactions [208], but examples of copper-induced cross-coupling in the absence of palladium catalysts have also been described recently. 

Piers and Wong [209] used intramolecular coupling between an alkenyltin and an alkenyl halide moiety to form a cyclic conjugated dienes in the presence of 2-3equiv. of CuCl in 

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As regards mixtures of ethylene and hydrogen, the reaction, C2H4 + H2 = C2H6, is not induced by-copper below 180°, but between 180—300° this is th main roaction. Metallic iron has no effect on th/ mixture at ordinary temperatures, aud when heated to 180° the reaction soon ceases owing to the metal becoming carburised. 

Anhydro-4-hydroxyoxazolium hydroxides were first obtained in 1974 by the decomposition of the a-diazoimides (295) induced by copper(II) acetylacetonate. The reaction proceeds by way of a carbene or a carbenoid species (equation 147). The triphenyl derivative is formed when the imide shown in equation (148) is treated with triethyl phosphite (82JOC723). 

Plant use of iron depends on the plant s ability to respond chemically to iron stress. This response causes the roots to release H+ and deduct ants, to reduce Fe3+, and to accumulate citrate, making iron available to the plant. Reduction sites are principally in the young lateral roots. Azide, arsenate, zinc, copper, and chelating agents may interfere with use of iron. Chemical reactions induced by iron stress affect nitrate reductase activity, use of iron from Fe3+ phosphate and Fe3+ chelate, and tolerance of plants to heavy metals. The iron stress-response mechanism is adaptive and genetically controlled, making it possible to tailor plants to grow under conditions of iron stress. 

Cyclopropenes have long been known to dimerize under copper catalysis, -and trienes are often isolated as minor components of other reactions of cyclopropenes induced by copper.They can also undergo dimerization on heating or even at room temperature or below, e.g. formation of 1, 2, and... 

In 2007, Shibasaki et al. reported a three-component domino reaction induced by cooperative catalysis between copper and zinc. This novel domino reaction occurred between acetophenone, diethylzinc and an allenic ester, providing the corresponding chiral lactone in high yield and excellent enantioselectivity of 96% ee, as shown in Scheme 3.1. The process began with the addition of diethylzinc to the allenic ester, which was followed by an aldolisation with acetophenone, and a lactonisation reaction gave the final product. Initially, the Cu(ii) was reduced to Cu(i) in the presence of... 

Coupling reactions and related fluoroalkylations with polytTuoioalkyl halides are induced by vanous reagents, among them metals such as copper and zinc, or by an electrochemical cell. More recently, examples of carbon-carbon bond forma tion by coupling of unsaturated fluorides have been reported Both acyclic and cyclic fluoroolefins of the type (Rp)2C=CFRp undergo reducUve dimerization on treatment with phosphines [42] (equation 33) The reaction shown in equation 33 IS also accompbshed electrocheimcally but less cleanly [43]... 

The importance of the o-hydroxyl moiety of the 4-benzyl-shielding group of R,R-BOX/o-HOBn-Cu(OTf)2 complex was indicated when enantioselectivities were compared between the following two reactions. Thus, the enantioselectivity observed in the reaction of O-benzylhydroxylamine with l-crotonoyl-3-phenyl-2-imi-dazolidinone catalyzed by this catalyst was 85% ee, while that observed in a similar reaction catalyzed by J ,J -BOX/Bn.Cu(OTf)2 having no hydroxyl moiety was much lower (71% ee). In these reactions, the same mode of chirality was induced (Scheme 7.46). We believe the free hydroxyl groups can weakly coordinate to the copper(II) ion to hinder the free rotation of the benzyl-shielding substituent across the C(4)-CH2 bond. This conformational lock would either make the coordination of acceptor molecules to the metallic center of catalyst easy or increase the efficiency of chiral shielding of the coordinated acceptor molecules. 

The reaction of crotonaldehyde and methyl vinyl ketone with thiophenol in the presence of anhydrous hydrogen chloride effects conjugate addition of thiophenol as well as acetal formation. The resulting j3-phenylthio thioacetals are converted to 1-phenylthio-and 2-phenylthio-1,3-butadiene, respectively, upon reaction with 2 equivalents of copper(I) trifluoromethanesulfonate (Table I). The copper(I)-induced heterolysis of carbon-sulfur bonds has also been used to effect pinacol-type rearrangements of bis(phenyl-thio)methyl carbinols. Thus the addition of bis(phenyl-thio)methyllithium to ketones and aldehydes followed by copper(I)-induced rearrangement results in a one-carbon ring expansion or chain-insertion transformation which gives a-phenylthio ketones. Monothioketals of 1,4-diketones are cyclized to 2,5-disubstituted furans by the action of copper(I) trifluoromethanesulfonate. ... 

The diastereoselective ultrasonically induced zinc-copper 1,4-addition of alkyl iodides to chiral a, (i-unsaturaied systems in aqueous media was studied by Suares and co-workers the Z-isomer gives good diastereos-electivities while reactions with the E-isomer are nonstereoselective.63 The 1,4-addition to chiral y, a-dioxolanyl-a, (i-unsaturated esters also proceeds with good yields (51-99%) (Eq.10.29).64... 

For the copper-induced decomposition of diazodiphenylmethane in acetonitrile, a fundamental difference in the catalytic action of Cu C104 and Cu ClO was detected. Whilst with CuC104, intermediary copper carbenoids are believed to be responsible for the mainly formed benzophenone azine402, CufClO initiates a chain reaction, promoted by radical cations and yielding mainly tetraphenylethene... 

Tanaka reported the synthesis of (/ )-muscone (10) by an enantioselective conjugate addition of chiral alkoxydimethylcuprate, which was prepared from chiral ercdo-3-[(l-methylpyrrol-2-yl)methylamino]-l,7,7-trimethylbicyclo[2.2.1]heptan-2-ol (9), methyllithium, and copper iodide (Scheme 9.7) [16]. In this reaction, convex deviation from a linear correlation was observed when the chiral ligand had a higher enantiopurity. This positive NLE was probably induced by the formation of a reactive homochiral dinuclear copper complex to give (R)-muscone. Rossitter also observed asymmetric amplification in a copper-catalyzed conjugate addition of methyl-... 

Ghyczy M, Boros M (2001) Electrophilic methyl groups present in the diet ameliorate pathological states induced by reductive and oxidative stress a hypothesis. Br J Nutr 85 409-414 Gilbert BC, Silvester S (1997) EPR studies of the role of copper in bio-organic free radical reactions. Copper-catalyzed oxidations of thiols with peroxides, especially those involving glutathione. Nukleonika 42 307-322... 

This reaction allows aryl carbon-heteroatom bond formation via an oxidative coupling of arylboronic acids, stannanes or siloxanes with N-H or O-H containing compounds in air. Substrates include phenols, amines, anilines, amides, imides, ureas, carbamates, and sulfonamides. The reaction is induced by a stoichiometric amount of copper(II) or a catalytic amount of copper catalyst which is reoxidized by atmospheric oxygen. 

Indirect evidence such as this does no more than indicate that the intermediate formed in copper-induced reactions is different from the carbenes thought to be produced in thermal and photochemical decompositions of diazoalkanes. However, the long-held view (Yates, 1952) that a carbene-copper complex is the reactive intermediate in these catalysed reactions gains strong support from a recent observation that the decomposition of ethyl diazoacetate induced by the chiral complex... 

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