Regioselective C–H Trifluoromethylation of Aromatic Compounds by Inclusion in Cyclodextrins

A regioselective radical C–H trifluoromethylation of aromatic compounds was developed using cyclodextrins (CDs) as additives. The C–H trifluoromethylation proceeded with high regioselectivity to afford the product in good yield, even on the gram scale. In the presence of CDs, some substrates underwent a single trifluoromethylation selectively, whereas mixtures of single- and double-trifluoromethylated products were formed in the absence of the CD. ¹H NMR experiments indicated that the regioselectivity was controlled by the inclusion of a substrate inside the CD cavity.