With ligand L2, we further explored the effects of the co-solvents, concentration, catalyst loading, and light source (Table ). It was established that product (R)-4a was formed in 57% yield with 87% ee, when using Cu(CH3CN)4PF6 (5 mol%) and ligand L2 (6mol%) in a mixed solvent of toluene and CH3CN under irradiation of 10 W purple LEDs.