Copper/BINOL-Catalyzed Enantioselective C–H Functionalization toward Planar Chiral Ferrocenes Under Mild Conditions

Copper-catalyzed enantioselective C–H activation
proceeding
through an inner-sphere mechanism remains a huge challenge. Herein,
a copper-catalyzed enantioselective C–H alkynylation with terminal
alkynes assisted by 8-aminoquinoline using readily available (S)-BINOL as the chiral ligand was disclosed. The reaction
proceeded under mild conditions with a catalytic amount of copper
salt, providing a range of chiral ferrocenes in good yields and enantioselectivities
(0 °C, up to 77% yield and 94% ee). The alteration of the stoichiometric
chemical oxidant with renewable electricity is also feasible at ambient
temperature, demonstrating the robustness of this copper/BINOL catalysis.
Notably, this is the first enantioselective cupraelectrocatalyzed
C–H activation reaction. Gram-scale synthesis, versatile transformations,
and application of the resulting oxazoline–olefin ligand in
asymmetric synthesis also highlight the utility of the protocols.