Fluoroform or trifluoromethane (CF3H), the by-product from tetrafluoroethylene (TFE) and chlorodifluoromethane (HCFC-22) generation, is a well-known greenhouse gas with a formidable global warming potential. Meanwhile, the extreme chemical stability of CF3H blocks the further application of this cheapest source of the trifluoromethyl (CF3-) group, especially as a replacement of bromotrifluoromethane (CF3Br), which was restricted by the Montreal Protocol, to prepare stable and useful organic CF3-building blocks. In 2012, the direct nucleophilic trifluoromethylation with CF3H and a strong organic base (KHMDS) was introduced by Prakash and co-workers [1,2]. Meanwhile, Dolbier and co-workers reported the use of fluoroform as a difluorocarbene source in the preparation of organic substrates of interest with difluoromethyl groups, now using potassium hydroxide (KOH) as the base in a two-phase process [3-5]. We now report another convenient one-step trifluoromethylation that applies CF3H with dimsyl-K, a much more economically efficient, strong base that is freshly prepared from potassium hydride (KH) and dimethyl sulfoxide (DMSO) [6].

Direct trifluoromethylation from fluoroform with dimsyl-K

253rd National Meeting (2017)

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