Copper-Catalyzed Cascade Radical Cyclization of Alkynoates: Construction of Aryldifluoromethylated Coumarins

A mild and simple method for the construction of 3-difluoroarylmethylated coumarins using α,α-difluoroarylacetic acids as an easily handled difluoromethyl source in reaction with ester 3-arylpropiolates under the promotion of copper. The reaction involves a proposed radical-triggered tandem decarboxylative aryldifluoromethylation/5-exo cyclization/ester migration process that directly form Csp2-CF2Ar and C-C bonds and good functional group tolerance of the reaction.