Cupric triflate

The oxidative dimerization of the anion of methyl phenyl sulfone (from a Grignard reagent) in ethereal solution in the presence of cupric chloride in 5% yield has been reported47. Despite the reported48 poor stability of the a-sulfonyl C-centered radicals, Julia and coworkers49 provoked the dimerization (in 13 to 56% yields) of the lithiated carbanion of alkyl phenyl sulfones using cupric salts as oxidants. The best results are obtained with cupric triflates in THF-isobutyronitrile medium (56% yield for R = H). For allyl phenyl sulfones the coupling in the 3-3 mode is predominant. 

Snider and Kwon use either cupric triflate and cuprous oxide or ceric ammonium nitrate and sodium bicarbonate as single-electron oxidants to convert d,s- and ,C-unsaturated enol silyl ethers 9 stereoselectively to the tricyclic ketones 14 in excellent yields [83, 84]. Based on comparison with other experimental data and literature results, the authors try to distinguish between several possible intermediates and propose the following mechanism with a very electrophilic radical cation 10 as the key intermediate. 

Wrapping up the nitrogen-based nucleophiles, aromatic amines were also noted to cleave epoxides in the presence of stannic or cupric triflate to form p-amino alcohols such as 86 directly. This protocol appears to be general for aromatic amines, even strongly electron-deficient ones. Aliphatic amines are completely unreactive under the same experimental conditions <99JOC287>. 

Reaction of the sandwich-type POM [(Fc(0H2)2)j(A-a-PW9034)2 9 with a colloidal suspension of silica/alumina nanopartides ((Si/A102)Cl) resulted in the production of a novel supported POM catalyst [146-148]. In this case, about 58 POM molecules per cationic silica/alumina nanoparticle were electrostatically stabilized on the surface. The aerobic oxidation of 2-chloroethyl ethyl sulfide (mustard simulant) to the corresponding harmless sulfoxide proceeded efficiently in the presence of the heterogeneous catalyst and the catalytic activity of the heterogeneous catalyst was much higher than that of the parent POM. In addition, this catalytic activity was much enhanced when binary cupric triflate and nitrate [Cu(OTf)2/Cu(N03)2 = 1.5] were also present [148],... 

With cyclohexene and silyl enol ethers, under these conditions, there was no cyclization the former gave a mixture of 3- and 4-bis(methoxycarbonyl)methyl-cyclohexenes, whereas the latter afforded RC0CH2CH(C02Me)2 (up to 60%) [24], Lactones were formed from PhI=C(C4F9)C02Et with catalysis by cupric triflate [25]. 

To a suspension of cupric triflate (20 mg, 0.055 mmol) in a solution of cyclohexene (0.54 ml, 0.43 g, 5.33 mmol) in acetonitrile (5 ml) the ylide (400 mg, 1.07 mmol) was added under a flow of nitrogen. When all of it went into solution, at room temperature, the reaction mixture was filtered through a plug of silica with 50 ml of ethyl acetate as eluent. Concentration and purification by flash column chromatography on silica (hexane-ethyl acetate 4 1) provided the title compound (161 mg, 60%) m.p. 55.5°C. 

It is well known that copper salts can catalyze the photocycloaddition of dienes [56]. The reaction can be very diastereoselective and useful as an access to polycyclic molecules, especially 1 - vinyl-2-allylcyclanes [57]. The reaction of vinylglycine, cinnamyl derivatives 76, and analogs is also catalyzed by Cu(I) produced in situ by the reduction of cupric triflate. The coordination of the double bonds to the copper ion during the [2 4- 2]-photocycloaddition process increase ... 

The salt can be prepared, undoubtedly as a complex with acetonitrile, by heating cupric triflate with copper powder at reflux in acetone containing some acetonitrile. 

Solutions of this salt can be obtained by the reaction of cupric triflate hydrate, Cu(CF3S03)2 5.5 H2O (2.70 mmole) with copper powder (2.50 mmole) in acetone (25 ml.) and acetonitrile (1.25 ml.). The reaction does not proceed in the absence of acetonitrile. 

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