Dearomatization-Rearomatization Strategy for Reductive Cross-Coupling of Indoles with Ketones in Water.

N-Alkylation of indoles is one of the important pathways for the construction of various biologically active indole molecules. Using ketones as N-alkylation reagent for indoles has been a great challenge not only because of the competing alkylation reaction of C-3 position but also because of the poor nucleophilicity of the nitrogen atom of indole, in addition to the steric hindrance and lower electrophilicity of the ketones. A dearomatization-rearomatization strategy has been developed for reductive cross-coupling of indoles with ketones in water. Various functional groups and other heterocyclic compounds are tolerated.