Palladium-catalyzed C-H ethoxycarbonyldifluoromethylation of electron-rich heteroarenes

The first Pd-catalyzed C-H ethoxycarbonyldifluoromethylation with BrCF₂CO₂Et has been developed. The use of a bidentate phosphine ligand (Xantphos) is critical for the reaction to occur. A variety of electron-rich heteroarenes, including indoles, furans, thiophenes, and pyrroles, can be ethoxycarbonyldifluoromethylated in moderate to excellent yields. The reactions take place at the C-H bonds adjacent to the heteroatoms with high regioselectivity. This method provides a new protocol for the introduction of difuoroalkyl groups into electron-rich heteroarenes.