Metal-free synthesis of fluorinated indoles enabled by oxidative dearomatization

Nitrogen heterocycles are found in a majority of approved small-molecule pharmaceuticals, and the number of approved fluorinated drugs is increasing each decade. Therefore, new approaches for accessing fluorinated nitrogen heterocycles are of great significance. A novel, scalable, and metal-free method for accessing a wide range of fluorinated indoles is described. This oxidative-dearomatization-enabled approach assembles 2-trifluoromethyl NH-indole products from simple commercially available anilines with hexafluoroacetylacetone in the presence of an organic oxidant. The nature of the aniline N-capping group is critical for the success of this new reaction. Furthermore, the indole products contain a 3-trifluoroacetyl group, which can be exploited to access a plethora of useful functional groups.