In the first reaction flask, resorcinol (0.72 g, 6.5 mmol), p-nitrophenylacetic acid (1.0 g, 6.0 mmol), and BF3/Et2O (10 mL) were added and the reaction was stirred for 90 min at 75 °C. Upon completion of the reaction, the reaction mixture was cooled to below 10 °C and DMF (10 mL) was slowly added under stirring. In a second reaction flask, DMF (20 mL) was added, cooled to below 10 °C, PCl5 (2.0 g, 9 mmol) was added in batches and stirred at 55 °C for 30 min. After the reaction was completed, cooled to below 10 °C, the mixture in the first reaction flask was added slowly and the reaction was continued for 1 h at room temperature. Upon completion of the reaction, the reaction solution was poured into hot dilute hydrochloric acid (0.1 N) with stirring, the solid was precipitated, filtered, washed with water and dried. The crude product was recrystallized from methanol to give 0.36 g of product in 16.4% yield.MS (ESI): m/z = 284 [M + H]+.
