Example 45 Synthesis of 3-bromo-5-methylbenzonitrile: Phosphorus pentoxide (29.8 g, 210.2 mmol) was added to a chloroform suspension of 3-bromo-5-methylbenzamide (15.0 g, 70.1 mmol), and the reaction mixture was stirred under reflux conditions for 2 days (the reaction progress was monitored by thin layer chromatography). Upon completion of the reaction, the mixture was cooled to room temperature and slowly poured into ice water with stirring. The organic layer was separated and the aqueous layer was extracted with dichloromethane (150 mL x 2). The organic phases were combined, washed with saturated saline and dried over anhydrous sodium sulfate. Purification by fast column chromatography afforded the target product 3-bromo-5-methylbenzonitrile (7.20 g, 52% yield).1H NMR (400 MHz, CDCl3) δ 7.60-7.56 (m, 2H), 7.40-7.39 (m, 1H), 2.39 (s, 3H).
