Scheme 2. The alkene scope for the oxidant-free C–H olefination of electron-rich arenes. General conditions: irradiation of a mixture of 1a (0.2 mmol), 2 (0.4 mmol), 3 mol% 4 and 10 mol% 6 in 4 mL 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. ^aα-Methyl–styrene was used as the coupling partner.