Aldehyde as a Traceless Directing Group for Rh(III)-Catalyzed C–H Activation: A Facile Access to Diverse Indolo[1,2‑a]quinolines

The aldehyde group has been developed for the first time as a traceless directing group to promote regioselective Rh­(III)-catalyzed C–H activation/cyclization of indolyl aldehydes with alkynes. This protocol streamlines access to a variety of appealing indolo­[1,2-a]­quinoline structures. As illustrative examples, a concise three-step synthesis of indolo­[1,2-a]­quinoline-based sensitizers is accomplished that exhibits the potential of C–H activation in the construction of organic optoelectronic materials.