Chiral Sulfoximine Mediated Cobalt-Catalyzed Atropselective C-H Annulation of Ynamides.

An achiral Cp*Co(III)-catalyzed enantioselective C-H activation/annulation of chiral sulfoximine-enabled thioamides with ynamides is presented herein. This method successfully synthesizes axially chiral five-membered 2-amidoindenones with good enantiocontrol. Interestingly, the annulation with chiral oxazolidone-containing ynamides could provide a separable mixture of diastereomers (up to ~10 : 1 dr). Moreover, enantiopure sulfoximines could be recovered with ~99 % purity, making this method practical. DFT studies show valuable insight into the mechanism and origin of asymmetric induction.