Sulfinate and Carbene Co‐catalyzed Rauhut–Currier Reaction for Enantioselective Access to Azepino[1,2‐a]indoles.

A carbene and sulfinate co‐catalyzed intermolecular Rauhut–Currier reaction between enals and nitrovinyl indoles is disclosed. The carbene catalyst activates the enal and the sulfinate co‐catalyst activates the nitrovinyl indole. Both activation processes are realized via the formation of covalent bonds between the catalysts and substrates to generate catalyst‐bound intermediates. The dual catalytic reaction affords azepino[1,2‐a]indole products with excellent stereoselectivity. Our study demonstrates the unique involvement of sulfinate as an effective nucleophilic catalyst in activating electron‐deficient alkenes for asymmetric reactions. This dual catalytic approach should also encourage future explorations of both sulfinate and carbene catalysts for new reactions. It takes two: A carbene and sulfinate co‐catalyzed intermolecular Rauhut–Currier reaction provides an efficient method to access azepino[1,2‐a]indoles with excellent stereoselectivity. The sulfinate was found to be a unique and effective nucleophilic catalyst in activating nitrovinyl indoles for the Rauhut–Currier reaction. [ABSTRACT FROM AUTHOR]