Development of N-centered radical scavengers that enables photoredox-catalyzed transition-metal-free radical amination of alkyl pinacol boronates.

Abstract

In recent years, amination of alkylboronates through ionic copper catalysis or boron-ate complex 1,2-metalation has been well established, but complementary radical processes remain less studied before. Herein, based on rational design, we develop several imine-type N-centered radical scavengers and apply them to the radical amination of alkylboronates. The reaction proceeds under mild photoredox-catalyzed transition-metal-free conditions and features excellent functional group tolerance. It also enables the preparation of a range of medicinally valuable amine derivatives from complex natural products. Further application of this reagent in C-H amination, deoxygenative amination, decarboxylative amination and three component trifluoromethylative/sulfonylative aminations are also realized. Further mechanistic studies and DFT calculations are conducted to provide detailed evidence for the mechanism.