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.