Bifunctional Photoactive Chiral Ligands Enable Visible-Light-Induced Nickel-Catalyzed Enantioselective C-O Coupling

Asymmetric metallaphotoredox catalysis (AMPC) typically relies on dual catalytic systems that often suffer from incompatibility between the photocatalytic and chiral metal catalytic cycles. Current strategies based on bifunctional chiral photoactive catalysts, while promising, are generally substrate-specific and metal-dependent. Therefore, the rational design of novel bifunctional photoactive chiral catalysts capable of promoting efficient enantioselective transformations remains an important yet challenging goal. Herein, we report the design and synthesis of a series of new bifunctional photoactive chiral ligands by incorporating carbazole (Cz) groups into a pyridine-oxazoline (Pyox) scaffold. This two-in-one design not only enhances the light-harvesting ability of the ligands but also enables more efficient intramolecular through-bond electron/energy transfer. Using these ligands, a visible-light-driven, enantioselective Ni-catalyzed C-O cross-coupling of heterobiaryls with diverse carboxylic acids was realized via a kinetic resolution (KR) process. The protocol proceeds under mild conditions with broad substrate scope and excellent functional group tolerance, affording a wide range of atropisomeric heterobiaryl esters and enantioenriched triflates in high yields and enantioselectivities. Mechanistic studies reveal that the incorporation of Cz groups into the Pyox ligand significantly enhances visible-light absorption, thereby promoting an efficient Ni(0)/Ni(II)/Ni(0) catalytic cycle.