Site-Specific Dehydrogenative Hydroxyfluoroalkylation of Indoles with Hexafluoroisopropanol

An efficient and convenient method for the synthesis of C3-hydroxytrifluoroalkylated indoles and pyrroles was described in this paper. The copper-catalyst-free site-specific cross-dehydrogenative coupling reaction of various indoles and pyrroles with hexafluoroisopropanol proceeded smoothly by using MnO₂ as oxidant to furnish a hydroxytrifluoroalkylated electron-rich <i>N</i>-heterocycle in satisfactory to excellent yields. Various groups, including the synthetically useful functional groups Cl, NO₂, and CN, were tolerated well. The mechanistic study revealed that a radical pathway accommodated the formation of a hexafluoroacetone intermediate.