Iodine → Phenanthrene

In a photoreaction container, argon was infused into a solution of 5.5 g (20.75 mmol) of stilbene in 7 L of acetonitrile at room temperature while stirring. After 10 minutes, 5.27 g (20.75 mmol, 1.0 eq.) of iodine and 58 mL (830 mmol, 40 eq.) of propylene oxide were added, followed by irradiation of light at room temperature while stirring. After 72 hours of irradiation, the disappearance of the raw materials was confirmed, and the resulting reaction liquid was concentrated. The residual product was dissolved in 500 mL of chloroform, followed by washing with 1 L of saturated sodium thiosulfate and 500 mL of brine. The organic layer was dried over magnesium sulfate, and then the solvent was distilled under reduced pressure to give a solid. The solid was collected by suction filtration using a Büchner funnel and a filtering flask, which was then washed with 50 mL of methanol twice. The solid was dried under reduced pressure at 60° C. to give 4.70 g (86.0%) of light brown powder.