89827-45-2

132-64-9

89827-45-2

Under nitrogen protection, 33.6 mg (200 mmol) of dibenzo[b,d]furan was dissolved in 700 mL of tetrahydrofuran (THF). After cooling the reaction system to -70 °C or lower, 350 mL of n-butyllithium (1.6 mol/L hexane solution) was slowly added. After addition, the reaction mixture was stirred by maintaining the temperature at -70°C or lower for 1 hour. Subsequently, the reaction system was warmed to 0°C and stirring was continued for 1 hour. The reaction system was again cooled to -70 °C or lower and 45 g (300 mL) of 1,2-dibromoethane was added dropwise. After the dropwise addition was completed, the reaction mixture was stirred at -70 °C or lower for 12 hours. Upon completion of the reaction, water was added to the reaction mixture and the product was extracted with ethyl acetate. The organic layers were combined, washed with water and concentrated under reduced pressure to remove the solvent. The resulting residue was recrystallized with hexane to give 37.1 g of Intermediate 1 in 75% yield. The structure of the product was confirmed by nuclear magnetic resonance (NMR) and mass spectrometry (MS) analysis.