Selective Electrosynthesis of (Trimethylsilyldifluoro)methylbenzene, a PhCF2- Precursor; Conditions for a Molar Scale Preparation without HMPA

Abstract

Electrochemical reductive silylation of trifluoromethylbenzene by the sacrificial anode technique selectively led, in a THF/DMPU mixture instead of THF/HMPA and according to the charge passed, to the corresponding mono-, bis- or tris-trimethylsilyl derivatives, respectively PhCF2 TMS, PhCF(TMS)2 and PhC(TMS)3. This reaction, without any chemical equivalent, was extended to a molar scale synthesis, using a tubular flow cell.