Site-Selective and Chemoselective C–H Functionalization for the Synthesis of Spiroaminals via a Silver-Catalyzed Nitrene Transfer Reaction

Although intense research over the last 2 decades revealed a diverse proficiency of nitrene species in chemistry disciplines, control of the selectivity in the reaction manifold has remained a challenge. We report herein the development of site-selective and chemoselective C–H functionalization involving nitrene species to synthesize densely functionalized spiroaminals. A rhodium catalyst generally used in nitrene chemistry gave amide C–N insertion products and/or the corresponding ketones, whereas a silver catalyst with an achiral bisoxazoline (BOX) ligand provided C–H insertion products. Mechanistic analysis based on integrated experimental and computational studies indicated that the nitrene transfer occurred through an asynchronous concerted process involving triplet spin-correlated radical pairs, affording the corresponding stereodefined spiromolecules.