Visible-Light-Driven Direct 2,2-Difluoroacetylation Using an Organic Pigment Catalyst

Ethyl 2-bromo-2,2-difluoroacetate reacted with alkenes during irradiation by a blue light-emitting diode (LED; 470 nm) in the presence of 10 mol % fluorescein to achieve the visible-light-driven direct 2,2-difluoroacetylation; the combination of N,N,N,N-tetramethylethylenediamine (TMEDA) as a reducing agent and 1-methyl-2-pyrrolidinone (NMP) as a solvent was essential to afford the desired 2,2-difluoroacetyl compounds, and 10 types of 2,2-difluoroalkanoates were obtained in moderate to excellent yields. The same reaction conditions were applicable to the 2,2-difluoroacetylation of alkynes to attain 10 types of 2,2-difluoroalkenoates in moderate to excellent yields.