Acetonitrile copper salt

Many of the early workers who studied the thermal decomposition reactions of diazocarbonyl compounds found that the addition of copper metal or copper salts allowed the reaction to be achieved at a lower temperature,<63AG(E)565, 64CB2628, 73JOU431> although no detailed study of this catalytic effect was undertaken. Alonso and Jano studied the copper-salt reaction of ethyl diazopyruvate 26 with acetonitrile and benzonitrile. The... 

Many transition-metal complexes have been widely studied in their application as catalysts in alkene epoxidation. Nickel is unique in the respect that its simple soluble salts such as Ni(N03)2 6H20 are completely ineffective in the catalytic epoxidation of alkenes, whereas soluble manganese, iron, cobalt, or copper salts in acetonitrile catalyze the epoxidation of stilbene or substituted alkenes with iodosylbenzene as oxidant. However, the Ni(II) complexes of tetraaza macrocycles as well as other chelating ligands dramatically enhance the reactivity of epoxidation of olefins (90, 91). 

Dissolve Cu CH3CN)4BF4 in 30 mL of previously degassed acetonitrile transferring the solvent by means of a double-tipped steel cannula. Stir until all the copper salt is dissolved. 

Recently, we found that a copper catalyst - as well as ruthenium - is effective for the oxidation of alkanes with molecular oxygen in the presence of acetaldehyde [157]. The catalytic system CUCI2 and 18-crown-6 has proved to be efficient [157cj. Furthermore, we found that specific copper complexes derived from copper salts and acetonitrile are convenient and highly useful catalysts for the aerobic oxidation of unactivated hydrocarbons [158], For example, oxidation of cyclohexane with molecular oxygen (1 atm of O2 diluted with 8 atm of N2) in the presence of acetaldehyde and Cu(OAc)2 catalyst (0.0025 mol%) in CH3CN/CH2CI2 (3 2) at 70°C in an... 

Ring-opening hydrolysis of thiazolidines under acidic or basic conditions gives aldehyde and amino thiol. Peptidyl aldehydes 111 were synthesized in excellent yields from thiazolidine peptides 112 using copper salts (CuO, CUCI2) in acetonitrile/water under the reducing conditions (Scheme 39) <1997TL2459>. 

Electrophilic cyclopropanes 392, which are useful intermediates in organic syntheses, can be prepared by the cyclopropanation of olefins with diethyl dibromomalonate and its derivatives (81MI4). The reaction is carried out in the presence of 1 mol equiv. of copper(II) bromide and 2-4 mol equiv. of DBU. Alternatively, the reaction can be effected with diethyl bromomalonate (83BCJ2687) in the presence of a catalytic amount of copper(II) bromide and a slight excess of DBU in benzene at ambient temperature. When some other base (e.g., triethylamine, DABCO, pyridine, or sodium hydride) was applied instead of DBU, the yield was lower or no reaction occurred. The use of other copper salts led to a decrease in the yield. When cyclopropanation was carried out in dimethyl sulfoxide, dimethylformamide, or acetonitrile, the yield of product 392 was again lower. 

P-Chlornviny/sulfones. In the presence of copper(l) or copper(II) salts as catalysts, sulfonyl chlorides add to acetylenes to give /J-chlorovinyl sulfones No reaction takes place in the absence of catalysts. Acetonitrile or methylene chloride is used as solvent. A small amount of a quarternaiy ammonium chloride (e.g., tetraethylammonium chloride) is added to solubilize the copper salts. The reaction is carried out at reflux or, preferably, in a sealed tube. The reaction is stereoselective thus the reaction of benzene-sulfonyl chloride (2) with phenylacetylene (1) leads to two isomeric 2-benzenesulfonyl-1-chlorostyrenes (3) and (4). The main product (3) results from trans addition, the... 

In the late 1980s, the group of Maumy described the first mild method for the EDP [23]. Prochiral phenylalkylmalonic acids 42 were decarboxylated at 60°C in acetonitrile in the presence of a combination of cinchonidine 26 and copper (I) chloride. Low enantiomeric excesses of carboxylic acids 44 were obtained using more than 1 equiv of cinchonidine 26 (due to the acidic character of the product) with a substoichiometric amount of the copper salt (Scheme 7.19). EDP, performed with racemic hemimalonates 45 using catalytic amounts of the copper-cinchonidine system (20 and 40 mol%, respectively), afforded comparative levels of enantioselec-tivity (Scheme 7.20). 

R. B. VanAtta, C. C. Franklin, J. S. Valentine, Oxygenation of organic substrates by iodosylbenzene catalyzed by soluble manganese, iron, cobalt, or copper salts in acetonitrile, Inorg. Chem. 23 (1984) 4121. 

While such a process had initially been observed as an undesired side-reaction in transformations where copper salts were employed as re-oxidants [13], Chemler demonstrated that various aminohalogenation reactions proceed in THF or acetonitrile in the presence of potassium carbonate as base [14]. These reactions employ palladium trifluoroacetate or palladium dibromide as catalyst source and require a moderate excess of the copper oxidant (3-4 equiv) giving moderate to excellent yields. However, they usually suffer from rather low selectivity, either in the initial aminopalladation or via subsequent rearrangement pathways to provide mixtures of pyrrolidines and piperazines (Scheme 4.2, Eq. (4.3)). A stoichiometric control reaction in the presence of palladium bromide led only to the Wacker cydization together with an alkene isomerization product, suggesting that the presence of copper(II) salts is crucial for the overall process. The exact role of the copper(II) salts has not yet been darified and palladium intermediates of different oxidation states may be involved in the final stage of carbon-halogen bond formation. 

The hydrolysis of the perfluoroalkylethyl iodides is catalyzed by certain metals. Copper salts (e.g., cupric sulfate) catalyze the hydrolysis of perfluoroalkylethyl iodides in aqueous acetonitrile heated at 160°C for 12 h, followed by heating in 10% NaOH at 70°C for 2 h [85]. A Hoechst patent [86] describes a process for preparing 2-perfluoroalkylethanol by a reaction of the iodide in water containing a metal and a phase transfer agent in an acid medium (pH 1-6). Another Hoechst patent [87] discloses a reaction of 2-perfluoroalkylethyl iodide with a peracid to yield 2-perfluoroalkylethanol. 

Irradiation of 3,5-disubstituted isoxazoles in alcoholic solvents gave reaction products such as acetals incorporating the reaction solvent. The use of triethylamine in acetonitrile media produced ketene-aminals by reductive ring cleavage. The reductive ring cleavage product was also obtained by irradiation of the isoxazole in alcohol in the presence of copper(II) salts (Scheme 3) (76JCS(P1)783). 

Decomposition of sulfonyl azides was shown to be catalyzed by copper in 1967 (72, 73). In the presence of alkenes, the reaction provides both aziridines and the C-H insertion products, albeit in low yields (73). In 1991, Evans et al. (74, 75) illustrated that both Cu(I) and Cu(II) salts were effective catalysts for nitrenoid transfer from [A-(/Moluenesulfonyl)imino]phenyliodinane (PhI=NTs) to a variety of acceptor alkenes. In the absence of ancillary ligands, reactions proceed best in polar aprotic solvents such as acetonitrile. Similar results are observed using both Cu(MeCN)4C104 and Cu(acac)2 as precatalysts, Eq. 53. 

Although the values of T igp are relatively large in water and in methanol, a finite amount of Cu(I) exists in any Cu(II) solution that is in contact with metallic copper. In fact, the molecularity associated with dictates that the fraction of copper in solution in the form of Cu(I) increases as the total concentration of solvated copper ion decreases. Thus, at micromolar levels in water, for example, the two oxidation states can be maintained in essentially equal amounts. In acetonitrile, the equilibrium for reaction 5 lies far to the left so that solvated Cu(I) is readily generated by placing copper metal in contact with a Cu(II) solution (conproportionation). As a consequence, the Cu(I) salt, [Cu(CH3CN)4]C104, is easily prepared [18] and is temporally stable. 

Substituted l,2,4-thiadiazol-5-yl diazonium tetrafluoroborates (314) react with potassium halides in acetonitrile in the absence of catalysts to afford the corresponding 5-halogeno compounds (315) in excellent yields.169 The isomeric 5-phenyl-l,2,4-thiadiazol-3-yl diazonium salts, however, resist substitution by this procedure, except with iodide ions by taking advantage of the catalytic effect of copper... 

---