General procedure for the synthesis of 2-bromodibenzo[b,d]furan from dibenzofuran: Under argon protection, dibenzofuran (3.36 g, 20 mmol), N-bromosuccinimide (NBS, 3.92 g, 22 mmol), zirconium chloride (ZrCl4, 0.10 g, 0.44 mmol) and N,N-dimethylformamide (DMF, 40 mL) were added to a 100 mL Schlenk flask equipped with a magnetic stirrer. The reaction mixture was stirred at 70 °C for 18 hours. Upon completion of the reaction, the reaction solution was slowly poured into water (200 mL) to precipitate solids and the suspension was continued to be stirred for 30 minutes. The solids were collected by filtration and the filter cake was washed with hot water (100 mL, 90 °C). The solid on the filter paper was recovered and dried to give 4.1 g of 2-bromodibenzo[b,d]furan in 83% yield.
