Direct Metal‐Free C–H Functionalization of Cyclic Ethers with Schiff Bases Through an Azobisisobutyronitrile‐Initiated Radical Chain Process

Abstract

The radical‐initiated C–H bond functionalization of cyclic ethers with imines represents an efficient way to form C–C bonds and construct 1,2‐amino ethers. Despite being a net redox‐neutral process, most examples require excess amounts of radical reagents or oxidants to continuously generate the radical species. Herein, we report an atom‐economic protocol for the radical addition of cyclic ethers to imines without the need for any oxidant, metal salt, delicate catalyst, or UV irradiation. In the presence of small amounts of AIBN (2 mol‐%), tetrahydrofuran smoothly undergoes the reaction with a variety of imines to afford 1,2‐amino ethers in moderate to good yields. Preliminary mechanistic studies suggest that this transformation likely proceeds through a radical chain process with the hydrogen atom abstraction as the rate‐determining step.