Ethers, copper® trifluoroacetate

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. 

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. 

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... 

Arylthallium bis(trifluoroacetates) (see 12-23) can be converted to aryl nitriles by treatment with copper(l) cyanide in acetonitrile. Another procedure uses excess aqueous KCN followed by photolysis of the resulting complex ion ArTl(CN)J 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%. Aromatic ethers ArOR have been photochemically converted to ArCN. 

Modification of the ketal substituents involved deketalization of RE 39571 with aqueous trifluoroacetic acid followed by reaction with the appropriately substituted ketone or aldehyde and anhydrous copper sulfate as the dehydrating agent (Scheme 3). If the glycoside-ether is the desired product, this can readily be obtained by glycosidation with methanol in the presence of hydrogen chloride followed by alkylation of the 2-hydroxyl group with the appropriate halide. 

Thallation of benzanilides with thallium tris(trifluoroacetate) in a mixture of trifluoroacetic acid and ether gave the c rr/to-thallated products. Reaction of these products with copper(I) acetylide in acetonitrile led to the 2-benzamidotolanes (119), which were eventually elaborated into the 2-phenyl-indole derivatives. 111 ... 

The first total synthesis of Cet /ojc is that of Masanao Matsui. [228] The starting material is )8-ionone [229] its side-chain double bond can be hydrogenated regioselectively on a copper catalyst. The side-chain is then extended by three carbon atoms by means of a Darzens reaction [230], followed by a Knoevenagel condensation. The (JS/Z)-isomeric mixture (1 1) of acids is separated by fractional distillation of their ethyl esters the ( )-isomer is hydrolysed and cyclised with trifluoroacetic add to sclareolide. Reduction of the latter with Vitride (sodium bis(2-methoxyethoxy)aluminium hydride) and ether formation then produces Cetalo . ... 

The room teiiq erature reaction of simple aliphatic ketones with an aqueous solution of thalllum(III) chloride leads to the formation of the mono-oxoalkylthalllum(III>. derivatives (23) which are then converted to selectively monochlorinated a-monochlorlnated ketones (Scheme 9> . Methyl vinyl ketone Is 8 arylated by arylthalllum conq>ounds In a reaction which Is catalysed by lithium tetrachloropalladate (Scheme 10) . The thallatlon of anilides with thalllum(III) trifluoroacetate In a mixture of trlfluoroacetlc acid and ether affords the ortho-thallated derivatives (24>, which yield 2-acetamldotolanes on reaction with copper(I> phenylacetyllde In acetonitrile. Ortho-... 

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