Copper trifluoroacetates

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. 

Reaction of a-diazoketones can also be catalysed by Lewis acids, and cyclization of a, y-unsaturated diazoketone has been used extensively in synthesis. The mechanism of the reaction has been investigated it is suggested that the Lewis acid adds to the carbonyl group, to give an intermediate such as 282, which cyclizes to 283 reaction is also catalysed by copper trifluoroacetate. Lewis acid catalysis has also been used to improve yields in cycloaddition reactions with nitriles, yielding oxazoles. 

To a reaction tube charged with copper trifluoroacetate hydrate (10.9 mg, 0.0375 mmol, 15mol%) and NHPI (8.2 mg, 0.05 mmol, 0.2 equiv.) was added a solution of acetaldehyde (1 mmol), TMSN3 (33 uL, 0.25 mmol, 1 equiv.), acetic acid (14 uL, 0.25 mmol, 1 equiv.), and H2O (135 pL, 7.5 mmol, 30 equiv.) in DMF (3 mL) under O2 (1 atm). The reaction mixture was then stirred at 80°C for 24 h. After cooling to room temperature, the mixture was diluted with ethyl acetate, washed with saturated sodium bicarbonate, water and brine, dried over anhydrous sodium sulfate, and concentrated in vacuo to give dark residue, which was purified by flash chromatography (using petroleum ether and ethyl acetate as the effluent) on silica gel to afford the 2-ketopyridine product. 

Trithiadiazepine 4 is readily thalliated by thallium(III) trifluoroacetate the product 19 reacts in situ with potassium iodide, copper(I) cyanide, and methanol/carbon monoxide300 to give 20a-c, respectively.33 ... 

A completely different concept13 makes use of a highly reduced bilane 5 which is oxidatively cyclized to an isobacteriochlorin 6 with copper(II) acetate. The ring closure is initiated by ester cleavage with trifluoroacetic acid and decarboxylative formylation with trimethyl orthoformate to yield a dialdehyde. One of the aldehyde functions forms the desired methine bridge whereas the other is lost during cyclization. 

Arylthallium bis(trifluoroacetate)s (10.70) are versatile synthons for various reactions, e.g., acylations (Larock and Fellows, 1982) and photolytic cyanations (Taylor et al., 1970), as shown in Scheme 10-93. Copper-catalyzed cyanations (Uemura et al., 1972) can be carried out at 115 °C with arylthallium (acetate)(perchlorate) (Scheme 10-94). 

Arylthallium bis(trifluoroacetates) (see 12-21) can be converted to aryl nitriles by treatment with copper(I) cyanide in acetonitrile. Another procedure uses excess aqueous KCN followed by photolysis of the resulting complex ion ArTl(CN)3 in the presence of excess KCN. Alternatively, arylthallium acetates react with Cu(CN)2 or CuCN to give aryl nitriles. Yields from this procedure are variable, ranging from almost nothing to 90 or 100%. 

Free-radical acyloxylation of aromatic substrates has been accomplished with a number of reagents including copper(II) acetate,benzoyl peroxide-iodine, silver(II) complexes, and cobalt(III) trifluoroacetate. ... 

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... 

Copper(II) triflate has also been used for the carbenoid cyclopropanation reaction of simple olefins like cyclohexene, 2-methylpropene, cis- or rran.y-2-butene and norbomene with vinyldiazomethane 2 26,27). Although the yields were low (20-38 %), this catalyst is far superior to other copper salts and chelates except for copper(II) hexafluoroacetylaeetonate [Cu(hfacac)2], which exhibits similar efficiency. However, highly nucleophilic vinyl ethers, such as dihydropyran and dihydrofuran cannot be cyclopropanated as they rapidly polymerize on contact with Cu(OTf)2. With these substrates, copper(II) trifluoroacetate or copper(II) hexafluoroacetylaeetonate have to be used. The vinylcyclopropanation is stereospecific with cis- and rra s-2-butene. The 7-vinylbicyclo[4.1.0]heptanes formed from cyclohexene are obtained with the same exo/endo ratio in both the Cu(OTf)2 and Cu(hfacac)2 catalyzed reaction. The... 

However, cyclopropanation of cyclohexene with methyl (a-diazomethyl)acrylate 3 in the presence of copper(II) trifluoroacetate furnished the 7-exo-substituted bicyclo-[4.1.0]heptane preferentially28). 

The substrates were admixed with 50 mol% of copper(I) chloride and small amounts of l-(2-propyl)-3-methylimidazolium hexafluorophosphate (pmimPF6) in dioxane. The mixture was heated to 110 °C within 2 min and kept at this reaction temperature for an additional 1 min. After cooling to room temperature, the product was rapidly released from the polymer support employing 20% trifluoroacetic acid (TFA) in dichloromethane, furnishing the corresponding bis-TFA salt in moderate yield. 

The magnesium complex 34 was demetalated with trifluoroacetic acid to produce the H2[pz(A3B1)] (35) (98%) followed by conversion into the corresponding copper complex Cu[pz (A3B x)] (36, 95%) with Cu(II) acetate. Alternatively, Compound 36 can be prepared directly from the magnesium complex 34 by treatment with trifluoroacetic acid in the presence of Cu(II) acetate (72%). All forms of the norbomadiene substituted pz precursors, M[pz (A3Bj)] A = dipropyl, B = benzonorbomadiene M = Mg, H2, Cu, 34-36, have... 

M[pz(A4)] A = S2ML2. The octakis(.V-R)porphyra/,ines reported by Schramm and Hoffman (2), M[pz(S-R)8 (M = Ni, Cu), (60), can be converted to the octathiolate M[pz(S )g] (Scheme 11) via reductive cleavage of the sulfur-carbon bond when R = benzyl (Bn), and this tetra-bis(dithiolate) can then be peripherally capped with metal-ligand systems to yield peripherally tetrametalated star porphyrazines. The benzyl dinitrile 57 can be macrocyclized around magnesium butoxide to form [Mg[pz(S-Bn)8] (58) (35-40%), which can then be demetalated with trifluoroacetic acid to form 59 (90%), which is subsequently remetalated with nickel or copper acetate to form 60a (95%) and 60b (70%) (Scheme 11) (3, 23, 24). Deprotection of 60a or 60b with sodium in ammonia yields the Ni or Cu tetra-enedithiolates, 61a or 61b to which addition of di-ferf-butyl or n-butyl tin dinitrate produces the peripherally metalated star porphyrazines 62a (37%), 62b (80%), and 62c (41%). 

Synthesis. Porphyrazines Mg[pz(A4)], A = S203 crown, 81a, and Mg[pz(A4)], A = S204 crown, 81e, (35%) were prepared by cyclizing the appropriate crown dinitrile 80. Compounds 81a and 81e were demetalated with trifluoroacetic acid and remetalated with either copper or manganese acetate to form compounds 81b-81d and 81f-81h (Scheme 16) (25-27). 

Synthesis. These macrocycles are prepared from seven-membered ring dinitrile complexes, 84a-84c (Scheme 17), which contain either methylene, sulfur or oxygen in the five position (129). These cyclic dinitriles are synthesized by alkylating maleonitrile dithiolate or derivatives thereof with the corresponding dihalide. The dinitriles 84a-84c can be cyclized in magnesium propoxide to form porphyrazines 85a (33%), 85b (19%), and 85c (27%) (Scheme 17), which can be demetalated with trifluoroacetic to form 86a-86c. Additionally, 86a has been remetalated with nickel (87a, 92%), copper (88a, 95%), and zinc (89a, 94%). The sulfur and oxygen derivatives 85b, 85c, 86b, and 86c are of low solubility and are not suitable for further manipulation. 

Cerium phthalocyanine, 7 64 Cerium tetrafluoride, 20 63-67 lattice parameters, 20 64 Cerium trifluoroacetates, 17 5, 26 Cermets, nitrides in, 9 81-82 Cerous ion, reaction with hydroxyl ions, 3 187 Ceruloplasmin, 40 123, see also Blue copper oxidases... 

Vanadium-catalyzed hydroxylation of benzene and cyclohexane has also been obtained with in situ generation of hydrogen peroxide from H2/O2 in the presence of palladium. A similar process has been settled for methane oxygenation to methyl trifluoroacetate and formic acid. Monoperoxovanadate, as well as copper hydroperoxides, have been indicated as the active species for the activation of the C—H bond of methane. 

Nitric acid, Sulfuric acid, Phloroglucinol, Hydrochloric acid Sodium chlorate. Copper sulfate. Ammonium hydroxide. Alcohol Sodium chlorate. Copper sulfate. Ammonium hydroxide. Alcohol Sulfuric acid. Potassium nitrate, 1,3,5-Trifluorobenzene, Methylene chloride. Hexane, Charcoal, Sodium sulfate, 2-Amino-2-methylpropanone, Potassium hydrogen carbonate, 1,2-Dichloroethane, Trifluoroacetic acid. Urea, Dimethylformamide Nitric acid. Urine... 

Due to the cost of trifluoromethyl iodide, other cheaper sources have been investigated for trifluoromethylation. Sodium trifluoroacetate reacted with aryl iodide in the presence of copper (I) iodide in NMP at 140 -160 °C to afford the corresponding coupling product [87]. No trifluoromethylation was observed without Cul. Under similar reaction conditions, sodium pentafluoropro-pionate worked well to give the pentafluoroethylated compounds [88, 89] (Scheme 28). 

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