Trifluoromethyl copper

Ullman type coupling occurs between aryl halides and trifluoromethyl copper species generated by the action of copper iodide on sodium tnfluoroacetate [168, 169] or on methyl fluorosulfonyldifluoroacetate [170] (equation 145) Similarly the pentafluoroethyl group can be introduced from potassium pentafluoropropion-ate [171] (equation 146)... 

Bis[trifluoromethyl] ditellurium and cadmium yielded bis[trifluoromethyltelluro] cadmium with copper powder, only tellurium and trifluoromethyl copper were formed, while silver did not react2. 

First, an organometallic compound is formed from dibromodifluoro-methane. Quite unexpectedly, trifluoromethyl copper is generated—who knows how ... 

Trifluoromethyl copper reacts with 4-chloro-3-nitrobenzotrifluoride in position 4. The carbanion of the organocopper compound, trifluoromethyl, attacks this position, because as a very strong nucleophile, it joins the carbon of the lowest electron density. The electron density of position 4 is decreased by the trifluoromethyl group in para position, and even more strongly by the nitro group in ortho position. The product is K, 3-nitro-1,4-bis-(trifluoromethyl)benzene [115]. 

Trifluoromethyl)copper reagents have a tendency to thermally decompose by oligomerization which is formally an a-elimination route. This pathway has been employed synthetically for the preparation of perfluoro(arylethyl) derivatives (Sections 2.1.1.3.3. and 2.1.1.3.5.). 

Perfluorophenyl)copper exhibits high reactivity towards organic substrates. and reacts with fluorinated or nonfluorinated aryl iodides (e.g., formation of 5), fluorinated vinyl iodides, al-kynyl bromides and iodides, allyl halides, alkanoyl halides, and iodomethane to afford the corresponding coupled products in good yields. (Perfluorophenyl)copper readily undergoes addition in a syn fashion to perfluorobut-2-yne to form a perfluorovinylcoppcr reagent 6, which can be quenched by electrophiles (e.g. formation of 7). Recall that (per-fluorophcnyl)coppcr reacts with (trifluoromethyl)copper to form (perfluorophenethyl)copper (Section 2.1.1.3.3.). 

A remarkable double insertion of difluorocarbene, derived from trifluoromethyl copper, has been reported [227] (Figure 9.87). 

Scheme 3.4S. Reaction 5 between trifluoromethyl copper and a variety of electrophiles [182]. ...

The aldehyde 234 is also applicable for construction of the proline skeleton. The oxazoline moiety of 234 was transferred to the N-CHC02H moiety of the prolines 249, the trifluoromethyl group of which was introduced by cross-coupling of bromide 244 with trifluoromethyl copper reagent (see Scheme 9.54) [82]. 

Scheme 2.118 Mechanism of the synthesis of trifluoromethyl zinc and cadmium reagents (top X, Y = Br, Cl M = Zn, Cd), and the preparation of trifluoromethyl copper(l) by in situ transmetalation (bottom).

In contrast, trifluoromethyl copper(I) can be generated and reacted, e. g. by thermal decarboxylation of trifluoroacetates in the presence of copper(I) salts at 150 °C, or by reaction of copper powder with perfluoroalkyl iodides. Nevertheless, even for the outwardly stable CFjCu there is evidence of a solvent- and temperature-dependent equilibrium between the trifluoromethyl copper(I) species and a difluorocar-... 

Trifluoromethyl copper has been shown to react with a 5-iodo-dioxinone (25) in the presence of HMPA to give the corresponding 5-trifluoromethyl derivative in 65% yield through an addition-elimination pathway (Equation (10)) <91CC1241>. 

Tetrakis(trifluoromethyl)thiophene 161 was synthesized by the reaction of per-fluorodiene with potassium sulhde or by exhaustive trifluoromethylation of tetra-iodothiophene using trifluoromethyl copper ... 

Recently reported by Cottet and Schlosser regioselective synthesis of tri-fluoromethyl pyridines and -quinolines" " " is based on the trifluoromethylation of iodoheteroarynes using CF3Si(CH3)3/KF/CuI system originally applied by Urata and Fuchikami for trifiuromethylation of aryl halides." Trifluoromethyl copper in this... 

Wiemers, D.M. Burton, D.J. Pregeneration, spectroscopic detection and chemical reactivity of (trifluoromethyl)copper, an elusive and complex species. J. Am. Chem. Soc. 1986, 108(4), 832-834. 

Cottet, R Schlosser, M. Trifluoromethyl-suhstituted pyridines through displacement of iodine by in situ generated (trifluoromethyl)copper. Eur. J. Org. Chem. 2002, (2), 327-330. 

One more method relied on reaction of CFjSiMes with AgF in DMF, which led to CFjAg species [281]. The latter was treated with copper to obtain the trifluoromethyl copper reagent, which was rather effective for the trifluoromethylation of 2-bromopyrimidine (75 % yield) (Scheme 108). In case of 5-bromopyrimidine, a mixture of perfluoroalkylation products 542-544 was formed at 56 41 3 ratio, respectively. 

Kobayashi Y, Yamamoto K, Asai T, Nakano M, Kumadaki I (1980) Studies on organic fluorine compounds. Part 35. Trifluoromethylation of pyrimidine and purine nucleosides with trifluoromethyl-copper complex. 1 Chem Soc Perkin Trans 1 2755-2761... 

Scheme 40 The synthesis of 8-trifluoroadenosines using a trifluoromethyl-copper complex...

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