BURTON Trifluoromethylation

BURTON Trifluoromethylation Trifluoromethylation of aryl iodides with Cd (Cu) reagents. 

Other references related to the Burton trifluoromethylation are cited in the literature. ... 

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,... 

Morken and Burton extended this methodology to the synthesis of /3,/3-difluoro-a-(trifluoromethyl)styrenes, as illustrated in equation 5334. The steric hindrance presented by... 

Burton and co-workers, as part of a series of ground-breaking studies on fluorinated organometallic systems [14], have established that trifluoromethyl derivatives may be obtained by reaction of halofluoromethanes with copper and other metals. The process involves electron transfer from the metal, with subsequent loss of halogen to form difluorocarbene which, in turn, generates very active fluoride ion by reaction with the solvent. The full process is indicated in Figure 10.60. 

Burton et al. have also isolated and characterized the very unusual Cu(III) trifluoromethyl compound Cu(S2CNEt2)(CF3)2 in which the coordination of the d% Cu(III) ion is essentially square planar (82). 

In the reactions of the organic substrates, the trifluoromethyl cadmium reagents are generally prepared in situ. See, for example, P. L. Heinze, and D. J. Burton, J. Fluorine Chem. 29, 359 (1985). 

Clark, J.H. McClinton, M.A. Blade, R.J. The direct trifluoromethylation of aryl chlorides using Burton s reagent. J. Chem. Soc., Chem. Commun. 1988, (10), 638-639. 

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. 

Scheme 105 Trifluoromethylation of 2-chloropyrimidine under Burton s conditions...

Burton DJ, Wiemers DM. A remarkahly simple preparation of (trifluoromethyl)cadmium and zinc reagents directly from difluorodihalomethanes. J. Am. Chem. Soc. 1985 107 5014-5015. 

---