General procedure for the synthesis of methyl 2-bromoquinoline-4-carboxylate from methyl 2-oxo-1,2-dihydroquinoline-4-carboxylate: 0.203 g of methyl 2-hydroxyquinoline-4-carboxylate (1 mmol) was dissolved in 20 ml of anhydrous toluene, followed by the addition of 0.356 mg of P2O5 (2.5 mmol). The reaction mixture was heated to 100°C and kept for 2 hours. After completion of the reaction, it was cooled to room temperature and the toluene layer was washed with 25 ml of saturated NaHCO3 solution and then with 25 ml of brine. The organic layer was dried over anhydrous sodium sulfate and the solvent was evaporated to give a light yellow solid product in 89% yield (0.237 g). The product was characterized by 1H NMR (DMSO-d6, 500MHz): δ 4.00 (s, 3H), 7.81 (td, 1H, J = 7.2Hz).
