Methylenecyclopropane Annulation by Manganese(I)-Catalyzed Stereoselective C-H/C-C Activation

C-H/C-C functionalizations with methylenecyclopropanes (MCPs) were accomplished with a versatile base-metal catalyst. A robust manganese(I) complex enabled the expedient annulation of MCPs by synthetically meaningful ketimines to deliver, upon one-pot hydroarylation, densely substituted polycylic anilines in a step-economical fashion. Mechanistic studies provided strong support for a facile organometallic C-H manganation, while typical cobalt, ruthenium, rhodium, and palladium catalysts were found completely ineffective.