Dearomatization Approach to 2‑Trifluoromethylated Benzofuran and Dihydrobenzofuran Products

A mild dearomatization enabled ortho-selective
replacement of an aromatic C–H bond with a hexafluoro­acetylacetone
(hfacac) substituent has been developed. This reaction is dependent
on a hypervalent iodine generated phenoxonium intermediate, a critical
choice of solvent, and reagent addition order. The fluorinated dihydrobenzofuran
product can be transformed into dihydrobenzofuran and benzofuran products
decorated with a 2-trifluoromethyl group. The 3-trifluoro­methylacyl
substituted benzofurans rapidly form hydrates, which can be reduced
to the corresponding alcohols.