[Synthesis]
General procedure: methyl 3-bromo-5-carbamoylbenzoate (2.8 g, 10.8 mmol, 1.0 eq.) was dissolved in POCl3 (30 mL) and the reaction mixture was heated to reflux at 100 °C overnight. After completion of the reaction, POCl3 was removed by distillation under reduced pressure, the residue was diluted with water and the aqueous phase was extracted with EtOAc (3 x 30 mL). The organic phases were combined, dried with anhydrous Na2SO4, filtered and concentrated under reduced pressure to give the crude product. The crude product was purified by silica gel column chromatography (petroleum ether/ethyl acetate, 20:1) to afford methyl 3-bromo-5-cyanobenzoate (2.5 g, 96% yield). The product was dissolved in THF (30 mL), LiOH-H2O (1.7 g, 41.6 mmol, 1.54 eq.) and H2O (10 mL) were added and stirred at room temperature overnight. After completion of the reaction, THF was removed under reduced pressure and the aqueous phase was acidified to pH 2-3 with dilute HCl and extracted with EtOAc (3 × 30 mL). The organic phases were combined, dried with anhydrous Na2SO4, filtered and concentrated under reduced pressure to give the crude product. The crude product was purified by silica gel column chromatography (CH2Cl2/MeOH, 50:1) to afford methyl 3-bromo-5-cyanobenzoate as a white solid (2 g, 85% yield).LC-MS: m/z 248.0, 249.9 [M + Na]+. 1H NMR (400 MHz, DMSO) δ 13.67 (br s, 1H), 8.40 (s , 1H), 8.24 (s, 1H), 8.24 (s, 1H). |