Asymmetric vicinal C(sp ³ )–H difunctionalization of saturated cyclic amines <i>via</i> synergistic photoredox, copper and chiral phosphoric acid catalysis

Existing strategies are typically limited to modifying a C-H site (α or β-position) of saturated cyclic amines, but the asymmetric difunctionalization of vicinal C-H bonds remains a formidable challenge. To address this challenge, this work introduces a synergistic catalytic system that merges visible-light photocatalysis with asymmetric copper and chiral phosphoric acid catalysis. This system enables the enantioselective synthesis of ring-fused amine skeletons by activating vicinal C-H bonds in straightforward saturated cyclic amines. The reaction proceeds in good yields (up to 76%) and excellent enantioselectivity (up to 92% ee). This work describes detailed mechanistic studies that identify the specific dual chiral catalytic system that forms the basis for the enantioselectivity.