Room-temperature Formal Aza-Wacker Cyclization through Synergistic Copper/TEMPO-catalyzed Radical Relay

Abstract

A formal aza-Wacker cyclization through a synergistic Cu/TEMPO-catalyzed radical relay pathway, using N-fluorobenzenesulfonimide (NFSI) as an external oxidant, is reported. In this efficient cyclization of alkenylated carbamates or amides at room temperature, the imidyl nitrogen-centered radical (NCR) generated by NFSI induces carbamate or amido NCR from the substrate via N–H homolysis to realize the radical relay process, which was supported by results of control experiments. This work provides an effective approach toward oxazolidinones, pyrrolidones, and isoindolinones under mild conditions.