Alkenes copper acetate

A hydroxy and an arylthio group can be added to a double bond by treatment with an aryl disulfide and lead tetraacetate in the presence of trifluoroacetic acid." Manganese and copper acetates have been used instead of Pb(OAc)4. ° Addition of the groups OH and RSO has been achieved by treatment of alkenes with O2 and a thiol (RSH)." Two RS groups were added, to give vie- dithiols, by treatment of the alkene with a disulfide RSSR and Bp3-etherate."° This reaction has been carried... 

Isoxazolidines were prepared from primary nitroalkanes and alkenes in the presence of catalytic amounts of copper acetate and 1-methylpiperidine (NMP). Under these reaction conditions, adduct 49 was obtained in quantitative yield starting from nitropentane and norbomene. 

Another widely used decarboxylation procedure involves the use of lead tetraacetate. Depending on the nature of the substrate and the reaction conditions, this reagent may transform a carboxylic acid into an alkane or alkene, or into the respective acetoxy derivative (Scheme 2.144). The most favorable conditions for alkane formation utilize a good hydrogen donor as the solvent. Usually this transformation is carried out as a photochemically induced oxidative decarboxylation in chloroform solution, as is exemplified in the conversion of cyclobutanecarboxylic acid in cyclobutane.In contrast, the predominant formation of alkenes occurs in the presence of co-oxidants such as copper acetate. ... 

Normally, the dominant products are the alkene and ester. These arise from the carbonium-ion intermediate by, respectively, elimination of a proton and capture of an acetate ion. The presence of copper acetate increases the alkene ester ratio. When oxidation is carried out in the presence of halide salts, alkyl halides are formed in good yield. The halide is believed to be introduced at the radical stage by a ligand-transfer reaction. 

Hutchings and coworkers have extensively studied the zeolites supported heterogenous catalyst for aziridination of alkene [57-58]. The catalyst was synthesized using ion exchange of NaY zeolite and CuCOAc). This zeolite supported copper acetate is then premixed with chiral bis(oxazoline) in acetonitrile. The catalysis further promoted by addition of nitrene donor PHI=NNs or PhI=NTs and the desired alkene (Scheme 11.5). 

A complex of a chiral, nonracemic bis(oxazoline) with CuOTf is a highly effective catalyst for as)mmetric cyclopropanation of alkenes. Copper(II) triflate complexes do not catalyze the reaction unless they are first converted to Cu by reduction with a diazo compound or with phenylhydrazine. CuOTf coirqjlexes are uniquely effective. Thus the observed enantioselectivity and catalytic activity, if any, are much lower with other Cu or Cu salts including halide, cyanide, acetate, and even perchlorate. Both enantiomers of the bis(oxazoline) ligand are readily available. Spectacularly high levels of asymmetric induction are achieved with both mono- (eq 8) and 1,1-disubstituted alkenes (eq 9). 

Earlier studies have also shown that a catalyst system consisting of palladium(II) and copper salts plus oxygen for the reoxidation did not work well,t in contrast to the result with the Wacker oxidation. However, if quinone or hydroquinone was added to a mixture of palladium acetate and copper acetate, oxygen could be used as an efficient oxidant for conversion of alkenes into allylic acetates. Thus, cyclohexene gave better than 85% cyclohexenyl acetate (Scheme 10). The combination of oxygen and cobalt or manganese acetate also works, but less well.t ... 

Regioselective synthesis of indoles is accomplished by in situ trapping of Wacker aldehydes with (1) (eq 4). o-Vinylacetanilides give indoles directly under similar reaction conditions. Iso-coumarins and 1-isoquinolinones are also prepared by this chemistry. Electron-deficient alkenes give acetals with (1) under Wacker conditions (see PaUadium(H) Chloride-Copper(I) Chloride) ... 

Aziridination of alkenes can be carried out using N-(p- to I ucncsu I I o n y I i m i n o) phenyliodinane and copper triflate or other copper salts.257 These reactions are mechanistically analogous to metal-catalyzed cyclopropanation. Rhodium acetate also acts as a catalyst.258 Other arenesulfonyliminoiodinanes can be used,259 as can chloroamine T260 and bromoamine T.261 The range of substituted alkenes that react includes acrylate esters.262... 

Whereas metal-catalyzed decomposition of simple diazoketones in the presence of ketene acetals yields dihydrofurans 121,124,134), cyclopropanes usually result from reaction with enol ethers, enol acetates and silyl enol ethers, just as with unactivated alkenes 13). l-Acyl-2-alkoxycyclopropanes were thus obtained by copper-catalyzed reactions between diazoacetone and enol ethers 79 105,135), enol acetates 79,135 and... 

A very recent addition to the already powerful spectrum of microwave Heck chemistry has been the development of a general procedure for carrying out oxidative Heck couplings, that is, the palladium)11)-catalyzed carbon-carbon coupling of arylboronic acids with alkenes using copper(II) acetate as a reoxidant [25], In a 2003 publication (Scheme 6.6), Larhed and coworkers utilized lithium acetate as a base and the polar and aprotic N,N-dimethylformamide as solvent. The coupling... 

Scheme 6.6 Oxidative Heck coupling of boronic acids and alkenes using copper(ll) acetate as a reoxidant.

Copper-catalyzed monoaddition of hydrogen cyanide to conjugated alkenes proceeded very conveniently with 1,3-butadiene, but not with its methyl-substituted derivatives. The most efficient catalytic system consisted of cupric bromide associated to trichloroacetic acid, in acetonitrile at 79 °C. Under these conditions, 1,3-butadiene was converted mainly to (Z )-l-cyano-2-butene, in 68% yield. A few percents of (Z)-l-cyano-2-butene and 3-cyano-1-butene (3% and 4%, respectively) were also observed. Polymerization of the olefinic products was almost absent. The very high regioselectivity in favor of 1,4-addition of hydrogen cyanide contrasted markedly with the very low regioselectivity of acetic acid addition (vide supra). Methyl substituents on 1,3-butadiene decreased significantly the efficiency of the reaction. With isoprene and piperylene, the mononitrile yields were reduced... 

Hosokawa, Murahashi, and coworkers demonstrated the ability of Pd" to catalyze the oxidative conjugate addition of amide and carbamate nucleophiles to electron-deficient alkenes (Eq. 42) [177]. Approximately 10 years later, Stahl and coworkers discovered that Pd-catalyzed oxidative amination of styrene proceeds with either Markovnikov or anti-Markovnikov regioselectivity. The preferred isomer is dictated by the presence or absence of a Bronsted base (e.g., triethylamine or acetate), respectively (Scheme 12) [178,179]. Both of these reaction classes employ O2 as the stoichiometric oxidant, but optimal conditions include a copper cocatalyst. More recently, Stahl and coworkers found that the oxidative amination of unactivated alkyl olefins proceeds most effectively in the absence of a copper cocatalyst (Eq. 43) [180]. In the presence of 5mol% CUCI2, significant alkene amination is observed, but the product consists of a complicated isomeric mixture arising from migration of the double bond into thermodynamically more stable internal positions. 

In a direct comparison, it was found that with substrate 6, rhodium(II) acetate directs the reaction toward C-H insertion, to give cyclopentane 7, whereas copper-bronze favors alkene insertion, yielding the cyclopropane 845-46. A similar selectivity for cyclopropanation has been achieved by using amide ligands on the rhodium catalyst4. ... 

Copper-catalyzed687-689 or photochemical690 reaction of alkenes with peroxy-esters, usually with tert-butyl peracetate (or rm-BuOOH in acetic acid), may be used to carry out acyloxylation or the synthesis of the corresponding allylic esters in good yields. In contrast to the oxidation with Se02, preferential formation without rearrangement of the 3-substituted esters takes place from terminal alkenes 691... 

For cyclopropanation of very electron-rich alkenes such as vinyl ethers copper(II) trifluoroacetate, copper(II) hexafluoroacetylacetonate or rhodium(II) acetate are the catalysts of choice. Copper trifluoroacetate catalysed cyclopropanation of vinyldia-zomethane with dihydropyran gives the corresponding vinyl cyclopropane adduct in low yield (equation 17). In contrast, catalytic decomposition of phenyldiazomethane in the presence of various vinyl ethers results in high-yield phenylcyclopropane formation (equations 18 and 19)27. 

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