4-Position-Selective C–H Perfluoroalkylation and Perfluoroarylation of Six-Membered Heteroaromatic Compounds

The first 4-position-selective C-H perfluoroalkylation and perfluoroarylation of six-membered heteroaromatic compounds were achieved using nucleophilic perfluoroalkylation and perfluoroarylation reagents. The regioselectivity was controlled by electrophilically activating the heteroaromatic rings, while sterically hindering the 2-position, with a sterically bulky borane Lewis acid. The reaction proceeded in good yield, even in gram scale, and by a sequential reaction without isolating the intermediates. This reaction could be applied to late-stage trifluoromethylation of a bioactive compound.