Transition-Metal-Controlled Synthesis of 11H-Benzo[a]carbazoles and 6-Alkylidene-6H-isoindo[2,1-a]indoles via Sequential Intermolecular/Intramolecular Cross-Dehydrogenative Coupling from 2-Phenylindoles.

A catalyst-controlled synthesis of 11H-benzo[a]carbazoles and 6-alkylidene-6H-isoindo[2,1-a]indoles is described. Pd(OAc)2 favored 6-alkylidene-6H-isoindo[2,1-a]indoles via intramolecular C-H/N-H CDC reaction, while [Cp*RhCl2]2 led to 11H-benzo[a]carbazoles through intramolecular C-H/C-H CDC reaction. Moreover, the synthesis of 11H-benzo[a]carbazoles via sequential intermolecular ortho C-H/olefin coupling and intramolecular C3-H/olefin coupling from 2-phenylindoles and alkenes can be operated in one pot.