Direct Decarboxylative Alkynylation of α,α-Difluoroarylacetic Acids under Transition Metal-Free Conditions

An efficient and generally applicable protocol for decarboxylative coupling of alpha,alpha-difluoroarylacetic acids with ethynylbenziodoxolone (EBX) reagents has been developed, affording alpha,alpha-difluoromethylated alkynes bearing various functional groups in moderate to excellent yields. Remarkably, this potassium persulfate (K2S2O8)-promoted reaction employs water as solvent under transition metal-free conditions, thus providing a green synthetic approach to alpha,alpha-difluoromethylated alkynes.