Scheme 4.

Mechanistic Experiments^a

^a(A) Radical trapping experiments were performed aryl halides 1 (0.2 mmol, 1 equiv), trialkyl phosphites 2 (0.6 mmol, 3 equiv), DBU (0.4 mmol, 2 equiv), PTZ (0.02 mmol, 10 mol %), and radical trapping agents ((0.4 mmol, 2 equiv), in CH₃CN (1 mL) using 427 nm LED. (B-1) Addition of aryl halide 1a to a mixture of PTZ + DBU. (B-2) Addition of phosphite 2a to a mixture of PTZ + DBU.