Aryl iodides trifluoromethylations, 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)... 

Tnfluorometltylation of aryl, alkenyl, and alkyl halides can be accomplished by heating methyl fluorosulfonyldifluoroacetate and the appropriate halide precursor with copper(I) iodide at 60-80 °C in DMF [27 7] (equation 145). Similar trifluoromethylations of aryl, benzyl, and vinyl halides can be carried out with fluorosulfonyldifluoromethyl iodide and copper metal in DMF at 60-80 °C [2 75] (equation 146). 

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). 

A CF3Cu solution can also be prepared by the reaction of bis (trifluoromethyl) mercury [90] or AT-trifluoromethyl-AT-nitrosotrifluoromethanesulfonamide (TNS-Tf) [91] with activated copper powder in dipolar aprotic solvents. Reaction with aryl iodides gave the corresponding trifluoromethylated aromatics in good yields. (Scheme 29). 

Trifluoromethylation of aryl iodides was carried out by the fluoride ion in duced cross-coupling reaction of aromatic iodides with trifluoromethyltnalkyl-silanes in the presence of copper salts [219] (equation 147) Some pentafluoro- ethyl derivative was also formed This methodology was extended to pentafluoroethyl-and heptafluoropropyltnethylsilanes [219]... 

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.). 

The trifluoromethylation of aryl iodides has been achieved using the reaction with (trifluoromethyl)-trimethoxyborate and a copper(I)/phenanthroline catalyst." A copper chloride/phenanthroline catalyst has also been used together with (TMP2Zn), zinc bis-tetramethylpiperidide, in the reaction of aryl iodides with perfluoroalkyl derivatives to yield arylperfluoroalkanes. The mechanism is thought to involve initial formation of bis(perfluoroalkyl)zinc species followed by rate-limiting transmetalation with copper halide and reaction with the aryl iodide to give the coupled product." ... 

Morimoto H, Tsubogo T, Litvinas N, Hartwig J (2011) A broadly appUcable copper reagent for trifluoromethylations and perfluoroalkylations of aryl iodides and bromides. 

Weng Z, Lee R, Jia W, Yuan Y, Wang W, Feng X, Huang KW. Cooperative effect of silver in copper-catalyzed trifluoromethylation of aryl iodides using MesSiCFs. Organometal-... 

Aromatic perfluoroaLkylation can be effected by fluorinated aUphatics via different techniques. One category features copper-assisted coupling of aryl hahdes with perfluoroalkyl iodides (eg, CF I) (111,112) or difluoromethane derivatives such as CF2Br2 (Burton s reagent) (113,114), as well as electrochemical trifluoromethylation using CF Br with a sacrificial copper anode (115). Extmsion of spacer groups attached to the fluoroalkyl moiety, eg,... 

Trifluoromethylation is the most important perfluoroalkylation reaction. Kobayashi and co-workers reported the trifluoromethylation of aryl, vinyl, alkyl halides with trifluoromethyl iodide in the presence of copper powder in aprotic solvents such as HMPA at 120-150 °C [83,84], and this methodology has been applied to the preparation of fluorinated pyrimidine and purine nucleosides [85,86] (Scheme 27). 

As well as a fluorine substituent, a trifluoromethyl group have recently attracted much attention as the shortest perfluoroalkyl group. A variety of methodologies for the introduction of a trifluoromethyl group into heteroaromatics have been also developed [102], In 1970, Kobayashi et al. reported the copper-mediated direct tri-fluoromethylation of aryl and heteroaryl halides using trifluoromethyl iodide as a source of a trifluoromethyl group [103]. Thus, l-(trifluoromethyl)isoquinoline was synthesized, albeit in low yield (Scheme 29). 

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