(Difluoromethyl)bis(2,5-dimethylphenyl)sulfonium Tetrafluoroborate

A Schlenk tube is charged with an acetonitrile (5.0 mL) solution of an aromatic alkene (0.250 mmol), D5630 (190 mg, 0.500 mmol), perylene (3.2 mg, 0.0127 mmol) and water (4.5 mg, 0.250 mmol) under a nitrogen atmosphere. The mixture is degassed by freeze-pump-thaw cycles. The Schlenk tube is placed at 2−3 cm away from blue LED lamps (λ = 425 ± 15 nm) in a water bath. The mixture is stirred for 6−12 h at room temperature under visible light irradiation. After the reaction, water (15 mL) is added and resulting suspension is extracted with dichloromethane (15 mL × 3). The combined organic layer is dried over sodium sulfate, and concentrated under reduced pressure. The purification by column-chromatography and repreciptitation affords the desired products.