Indole‐Quinoline Transmutation Enabled by a Formal Rhodium Carbynoid

Skeleton editing is an emerging and powerful tool in organic chemistry because it can simplify synthetic procedures towards complex molecules. Herein, we present an approach for indole‐quinoline transmutation through rhodium‐catalyzed single‐carbon insertion into the C2(sp2)–C3(sp2) bond of an indole with an α‐diazotrifluoroethyl sulfonium salt that we developed. This protocol involves a formal trifluoromethyl rhodium carbynoid (CF3C+=Rh) resembling a trifluoromethyl cationic carbyne (CF3C+:), allowing facile access to an array of quinolines in moderate to high yields. Potential applications in the late‐stage skeletal editing of pharmaceutical and natural product derivatives, preparation of adapalene analogs, scaled‐up synthesis, and transformations of products are highlighted. Finally, a computational study was conducted to support the envisioned mechanism.