Intermolecular Enantioselective Benzylic C(sp3)-H Amination by CationicCopper Catalysis.

Abstract

Chiral benzylic amines are privileged motifs in pharmacologically active molecules. Intramolecular enantioselective radical C(sp3)-H functionalization by hydrogen-atom transfer has emerged as a straightforward, powerful tool for the synthesis of chiral amines, but methods for intermolecular enantioselective C(sp3)-H amination remain elusive. Herein, we report a cationic copper catalytic system for intermolecular enantioselective benzylic C(sp3)-H amination with peroxide as an oxidant. This mild, straightforward method can be used to transform an array of feedstock alkylarenes and amides into chiral amines with high enantioselectivities, and it has good functional group tolerance and broad substrate scope. More importantly, it can be used to synthesize bioactive molecules, including chiral drugs. Preliminary mechanistic studies indicate that the amination reaction involves benzylic radicals generated by hydrogen-atom transfer.