Scheme 3. The arene scope for the oxidant-free C–H olefination of electron-rich arenes. General conditions: irradiation of a solution of 1 (0.2 mmol), 2 (0.4 mmol), 3 mol% 4 and 10 mol% 6 in DCE by blue LEDs for 24 h. The isolated yields are shown and the ratios of E/Z isomers or regioisomers were determined by GC-FID and are shown in parenthesis. ^a100 μL 1,1,1,3,3,3-hexafluoro-2-propanol was added. ^bPhotosensitizer 8 was used.