Catalyst-free defluorinative alkylation of trifluoromethyls

Abstract

Photocatalytic defluorinative alkylation of trifluoromethyl groups is an attractive method for building important difluoromethyl structures. However, these methods rely on the use of complex, expensive, and toxic photocatalysts and hydrogen atom transfer reagents (thiols). In addition, substrates are limited to substituted alkenes in these systems. Herein, a visible-light-promoted catalyst- and additive-free strategy for the defluorinative alkylation of trifluoromethyl groups is presented. A broad range of polyfluorinated compounds was easily converted into difluoromethyl products. Simple and inactivated alkenes, such as ethylene, were found to be suitable substrates. Furthermore, complex deuterated α,α-difluoromethyl derivatives could be obtained. The mechanism was investigated by combining experimental and theoretical methods, which revealed that the in situ generated dimsyl and thiol radicals are key intermediates for the generation of CO₂˙⁻. We expect that this strategy will have a wide application in the construction of difluoromethyl units.