Fig. 3. Screening of the photocatalysts.

Reactions were conducted with 1a (0.4 mmol), 2a (0.2 mmol), 4-nitrophthalonitrile (0.02 mmol) in DMSO (2 mL) under nitrogen atmosphere at room temperature with 390 nm LEDs irradiation for 24 h. Yields were determined by ¹H NMR analysis of crude products using 1,3,5-trimethoxybenzene as internal standard.