Example 1A Synthesis of 2-bromo-4-chlorobenzonitrile: 588 mg (2.5 mmol) of 2-bromo-4-chlorobenzoic acid was dissolved with 300 mg of urea in a mixed solvent of dichloromethane/methanol, and subsequently concentrated over 364 mg of neutral alumina by rotary evaporator. The resulting mixture was microwaved at 150 °C for 60 min. After completion of the reaction, the reaction mixture was cooled and the residue was stirred with ethyl acetate and water, followed by filtration and separation of the aqueous phase. The organic phase was washed with sodium bicarbonate solution, dried over anhydrous sodium sulfate, then concentrated by rotary evaporator and finally dried under high vacuum. The crude product 383 mg (80% purity, 57% yield) was obtained, which could be used for subsequent reactions without further purification.1H NMR (300 MHz, CDCl3) δ: 7.72 (d, 1H), 7.60 (d, 1H), 7.42 (dd, 1H).
