To investigate the electron transfer process, electron paramagnetic resonance (EPR) experiments were conducted using 5,5-dimethyl-1-pyrroline N-oxide (DMPO) as a free radical spin trapping agent, substrate (1-(4bromophenyl)ethan-1-one), Cu(CH3CN)4PF6, and BINAP under blue light irradiation for 20 mins. The EPR signals of a carbon-centered radical (g = 2.004, AN = 1.46 mT, AH = 2.24 mT), and Cu(II) (g∥ = 2.22, g⊥ = 2.03) were detected, supporting the single electron transfer (SET) from excited Cu(I) catalyst to the substrate. Additionally, fluorescence quenching of the excited Cu(I) complex by the aryl halide was observed, while the sulfinate salt failed to quench. Based on these preliminary mechanistic investigations, the authors propose a plausible mechanistic pathway involving oxidative quenching of excited copper (I) complex by the aryl halide (Figure ). The generated aryl radical (12.9) rebounds on copper (II) forming copper (III)-aryl species (12.10). Subsequent ligand exchange from sulfinate salt and reductive elimination deliver the organosulfones (12.3) and regenerate copper catalyst to close the catalytic cycle.