Trifluoromethylation of aromatics

Cheaper sources of tnfluoromelhyl groups have been the goal of several groups The use of sodium tnfluoroacetate and copper (1) iodide in dipolar aprotic solvents gave regiospecific trifluoromethylation of aromatic halides [202] (equation 136)... 

Experiments were performed with various sulfoxylate radical anion precursors sodium dithionite, sodium hydroxymethanesulfinate or a mixture of sulfur dioxide with a reductant, such as zinc or sodium formate (refs. 29, 30).In contradistinction with the trifluoromethylation of aromatic compounds (Figs. 19,20), a stoiechiometric amount of the sulfoxylate radical anion precursor was necessary. In the disulfide case, there is no intermediate able to reduce back the sulfur dioxide which is formed in the medium (Fig. 22). 

Paratian, J.M. SihiUe, S. Perichon, J. An efficient electrochemical trifluoromethylation of aromatic hahdes with hromotrifluoromethane and a sacrificial copper anode. J. Chem. Soc., Chem. Commun. 1992, 53-54. 

Kobayashi, Y Kumadaki, I. Trifluoromethylation of aromatic compounds. Tetrahedron Lett. 1969, (47), 4095-4096. 

Matsui, K. Tobita, E. Ando, M. Kondo, K. A convenient trifluoromethylation of aromatic halides with sodium trifluoroacetate. Chem. Lett. 1981, (12), 1719-1720. 

Feng developed a combinatorial catalyst system containing the ehiral sodium binaphtholate 49 and a quinidine-derived chiral quaternaiy ammonium salt 50 for the enantioseleetive trifluoromethylation of aromatic aldehydes in up to 71% ee (Scheme 2.31). A lack of either 49 or 50 completely prevented the reaction from proceeding. 

SCHEME 9.6 Overview of fluorination and trifluoromethylation of aromatic compounds. 

Aromatic Compounds. Nucleophilic trifluoromethylation of aromatic compounds containing nitro, fluoro, and trifluoromethyl... 

Sawada H, Nakayama M, Yoshida M, Yoshida T, Kamigata N (1990) Trifluoromethylation of aromatic compounds with bis(trifluoroacetyl) peroxide. J Fluor Chem 46 423-431... 

KobayashiY, Kumadaki I (1980) Studies on organic fluorine compounds. Part 27. Abnormal reactions in the trifluoromethylation of aromatic compounds with trifluoromethyl iodide and copper powder. J Chem Soc Perkin Trans 1 661-664... 

Tanabe Y, Matsuo N, Ohno N (1988) Direct perfluoroalkylation including trifluoromethylation of aromatics with perfluoro carboxylic acids mediated by xenon difluoride. J Oig Chem 53 4582-4585. doi 10.1021/jo00254a033... 

Strekowski L, Hojjat M, Petterson S, Kiselyov A (1994) Experimental and computational studies of trifluoromethylation of aromatic amines by the system trifluoroiodomethane-zinc-sulfur dioxide. J Heterocycl Chem 31 1413-1416... 

Kobayashi Y, Kumadaki I, Sato S, Hara N, Chikami E (1970) Studies on organic fluorine com-poimds. VII. Trifluoromethylation of aromatic compoimds. Chem Pharm Birfl 18 2334-2339... 

Yamakawa described an interesting iron-mediated oxidative trifluoromethylation of aromatic compounds using iodotrifluoromethane and an iron catalyst in the presence of hydrogen peroxide. The reaction was effective for an extensive range of (hetero)aromatic substrates, again with the production of regioisomers in some cases (Scheme 15.96). 

As noted in Scheme 15.108, Yu reported a C-H functionalisation approach that was catalytic in palladium for the trifluoromethylation of aromatic moieties.Similarly, Shi has reported a catalytic palladium system for the amide directed C-H trifluoromethylation. Recently, Sanford has reported a decarbonylative trifluoromethylation catal5dic cycle based on a Pd(0)/Pd(ii) system this observation may open up new opportunities in this important area (Figure 15.9). ... 

A study of the addition of Me3SiCN to aldehydes catalysed by four Lewis bases (Et3N and Bu4N" X, where X = CN, N3, or SCN) has revealed three different reaction mechanisms there was spectroscopic evidence of formation of a hypervalent silicon species by each of the ammonium salts. ° Asymmetric trifluoromethylation of aromatic aldehydes by Me3SiCF3 is catalysed cooperatively by (IPr)CuF and a quinidine-derived quaternary ammonium salt. ... 

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