Salicylaldehyde-Enabled\nCo(II)-Catalyzed Oxidative\nC–H Alkenylation of Indoles with Olefins

A ligand-promoted oxidative dehydrogenation C–H\nalkenylation\nof indoles and olefins was achieved using commercial and low-cost\nCo(NO<sub>3</sub>)<sub>2</sub>·6H<sub>2</sub>O as a catalyst\nand Mn(OAc)<sub>2</sub> as an oxidant. The design and selection of\nelectrically unique methyl-substituted salicylaldehyde as a ligand\nis the key to achieve this transformation. This protocol can introduce\nan indole backbone into diverse bioactive molecules such as ibuprofen,\nnaproxen, and Estrol for late-stage synthetic modification, which\nhas potential applications in the discovery of drug molecules containing\nan indole motif.