Photoinduced Copper-Catalyzed Asymmetric C-O Cross-Coupling

Whereas considerable advances have recently been achieved in radical-involved catalytic asymmetric C-N bond formation, there has been little progress in the corresponding C-O bond-forming processes. Here we describe a photoinduced copper-catalyzed cross-coupling of readily oxime esters and 1,3-dienes to generate diversely substituted allylic esters with high regio- and enantioselectivity (>75 examples; up to 95% ee). The reaction proceeds at room temperature under excitation by purple light-emitting diodes and features the use of a single, earth-abundant copper-based chiral catalyst as both the photoredox catalyst for radical generation and the source of asymmetric induction in C-O coupling. Combined experimental and DFT computational studies suggest the formation of π-allylcopper complex from redox-active oxime esters as bifunctional reagents and 1,3-dienes through a radical-polar crossover process.