Tetrahydrofuran → 1-Bromo-4-(ethenyloxy)benzene

Tert-Butoxypotassium (33.7 g, 300 mmol) was added to a solution of tetrahydrofuran (hereinafter THF) (250 mL) containing 1-bromo-4-(2-chloroethoxy)benzene (58.6 g, 249 mmol) prepared in Example 6 (6a) over 10 minutes at −10° C. The mixture was stirred at room temperature for 21 hours, and water (500 mL) was added thereto. The resulting mixture was extracted with methyl tert-butyl ether (200 mL, 150 mL) twice. The organic layers were combined, washed with saturated brine (100 mL) twice, and dried over anhydrous magnesium sulfate. Then, the solvent was evaporated. The resulting residue was dissolved in hexane (100 mL), and the precipitated insoluble substance was removed by filtration. The insoluble substance was further washed with hexane (5 mL) five times. The filtrates were combined, concentrated, and purified by silica gel column chromatography (hexane) to give 39.0 g of the title compound (colorless oil, yield: 79%).