Preparation and Reaction of Trifluoromethy-Metal Complexes

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1. Trifluoromethylation by Electron-Transfer Reaction from Chalocogenides to Trifluoromethyl Bromide.Reaction of trifluoromethyl bromide (CF_3Br) with chlalcogenides (Ar-X^-, X ; S, Se, Te) proceeds smoothly, generating CF_3・radicals which are trapped with Olefins. Thus, 1, 2-addition of CF_3 and Ar-X units to carboncarbon bond was performed. One electron transfer from ArX^- to CF_3Br was proposed where the order of the reactivity of ArX^- is as follows ArTe > ArSe > ArS. Particularly, arene telluride reacts even at -40^ﾟC. Electron-rich olefins are more reactive so that vinyl ethers give a reasonable yield of 1, 2-addition products. Reaction of arene thiolate is slower than that of the corresponding selenide. However, a small amaunt of selenide catalyzes the trifluoromethyl-sulfenylation. This result suggests that arene-selenide mediated trifluoromethgl-alkylation and the related 1, 2-addition would be possible.2. Electrochemical TrifluoromethylationElectrochemical oxidation of trifluoroacetic acid in the presence of butyl acrylate under oxygen atmosphere provides trifluoromethylated -oxo of -hydroxy carboxylate in 45% yield. The trifluoro-methylated carbon radicals are trapped with molecular oxygen leading to the desired carboxylate. Content of water in methanol affected the yield of the oxygenated compounds presumably because water is electro-oxidized in the same conditions of TFA oxidation.