Cobalt-Catalyzed Dearomatization of Indoles via Transfer Hydrogenation To Afford Polycyclic Indolines.

A cobalt-catalyzed dearomatization of indoles via transfer hydrogenation with HBpin and H2O has been developed. This reaction offered a straightforward platform to access hexahydropyrido[1,2-a]indoles in high regio- and chemoselectivity. A preliminary reaction mechanism was proposed on the basis of deuterium-labeling experiments, and a cobalt hydride species was involved in the reaction.