CH Functionalization via Asymmetric Nitrene Transfer

The prevalence of amines in natural products and pharmaceuticals has stimulated interest in efficient, asymmetric methods to transform CH to CN bonds. Transition metal-supported nitrene intermediates can undergo ready insertion into a variety of CH bonds via nitrene transfer (NT), provided the chemo-, site-, and enantioselectivity can be controlled in a predictive manner. In recent years, the field of transition metal-catalyzed asymmetric nitrene transfer has grown rapidly with the design of new ligand scaffolds and the addition of a host of biocatalysts to the catalog of catalysts able to furnish diverse enantioenriched amine products. This article focuses on the recent advances in the arena of both intra- and intermolecular asymmetric CH aminations. The key differences between the types of catalysts utilized in asymmetric CH functionalization via NT will be highlighted, both in terms of the metal identity and ligand design. The article is organized by metal identity and concludes with a discussion of areas where opportunities and challenges still remain in the field.