SET or TET? Iron-catalyzed aminocarbonylation of unactivated alkyl halides with amines, amides, and indoles via a substrate dependent mechanism

Iron-catalyzed carbonylation reactions are highly desirable in our sustainability-advocating chemical community because of its low cost, abundance, and potential for distinct and complementary reactivity patterns. Meanwhile, alkyl bromides as well as low nucleophilic amides and indoles are considered to be particularly challenge substrates for carbonylation reactions. Herein, we report an iron-catalyzed carbonylative coupling of unactivated alkyl halides with amines, amides, and indoles to assemble amide structural units, affording various amides, imides and N-acyl indoles with excellent yields and unprecedented functional group compatibility. Remarkably, our approach also represents the example on Fe-catalyzed aminocarbonylation of alkyl halides. Our preliminary mechanistic studies suggest that the reaction pathway is substrate dependent: the carbonylation proceeds via a radical pathway when alkyl iodides were used; while a two-electron transfer (TET) process occurred when alkyl bromides served as the electrophiles.