Catalytic C(sp2)–H Trifluoroethylation of Indoles via Iron‐Carbene Insertion

Pharmacological properties of a bioactive molecule can be improved significantly by placing a fluoroalkyl group on its scaffold. However, direct stitching of fluoroalkyl groups to aromatic compounds via C–H bond activation or insertion reaction is a difficult task, thus challenging and of high demand. Herein, an alternative to the Friedel‐Crafts alkylation, we describe an uncharted strategy for selective and efficient trifluoroethylation of indole that relies on iron(III)‐catalyzed C–H activation of aromatic compounds and proceeds via Fe(III)‐carbene insertion into C(sp2)–H bond of indole using trifluoroacetaldehyde N‐triftosylhydrazone as a carbene precursor and FeTPPCl as catalyst.