Visible-Light Induced Ipso-Difluoromethylation of N-Arylpropiolamides to Synthesize 3-Difluoromethyl Spiro[4.5]trienones

A visible light-induced radical ipso-difluoromethylation of N-arylpropiolamides to synthesize 3-difluoromethyl spiro[4.5]trienones was developed for the first time. In this transformation PhI(O2CCHF2)(2) was used as difluoromethylation reagent and PhI(OAc)(2) was employed as oxidant. Due to the cheap and readily accessible reagents and oxidant as well as the mild reaction conditions, this method is as an efficient and practical strategy for the synthesis of difluoromethyl-substituted spiro[4.5]trienones.