Visible-light-initiated tandem synthesis of difluoromethylated oxindoles in 2-MeTHF under additive-,metal catalyst-,external photosensitizer-free and mild conditions

An efficient and eco-friendly protocol for synthesizing difluoromethylated oxindoles through a visiblelight induced one-pot tandem reaction of N-arylacrylamides,difluoroacetic acid and Ph I(OAc)_(2)was developed.This reaction proceeded in the absence of any additive,base,metal-catalyst and external photosensitizer,using cheap and easily available CHF_(2)CO_(2)H as the difluoromethylation reagent and bulk biomass-derived 2-Me THF as the sole solvent.26 Examples of N-arylacrylamide substrates were investigated,and all of them successfully underwent difluoromethylation to deliver the target products in good to excellent yields.