Ethyl 3-broMo-4-cyanobenzoate

7149-03-3

362527-61-5

General procedure for the synthesis of ethyl 3-bromo-4-cyanobenzoate from ethyl 3-bromo-4-aminobenzoate: ethyl 4-amino-3-bromobenzoate (23.5 g, 96.3 mmol) was dissolved in dichloromethane at -10 °C, and tert-butyl nitrite (14.0 mL, 118.4 mmol) was added drop-wise followed by boron trifluoride diethyl ether compound ( 18.4 mL, 146.5 mmol). The reaction mixture was naturally warmed to room temperature with continuous stirring for 4 hours. Upon completion of the reaction, it was diluted with ether and filtered. The filter cake was dried, dispersed in toluene, cooled to 0 °C, and an aqueous solution of copper(I) cyanide (11.5 g, 129.2 mmol) and sodium cyanide (15.8 g, 323.1 mmol) was added sequentially. The mixture was stirred at 0 °C for 30 min, then warmed to 60 °C and continued stirring for 1 h. The reaction solution was cooled to room temperature. The reaction solution was cooled to room temperature and diluted with ethyl acetate and water. The organic phase was separated, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue was crystallized by ether/hexane to give ethyl 3-bromo-4-cyanobenzoate as an off-white solid in a yield of 18.6 g (76% yield). The ester (8.5 g, 33.6 mmol) was dissolved in tetrahydrofuran, sodium hydroxide solution (30 mL, 2.5 N) and ethanol were added and stirred for 20 hours. The reaction solution was acidified with 2N hydrochloric acid and extracted with ether. The ether extracts were combined, dried with anhydrous magnesium sulfate and concentrated under reduced pressure. The residue was crystallized by ether/hexane to give 3-bromo-4-cyanobenzoic acid as a beige solid in a yield of 6.81 g (90% yield). The product was confirmed by 1H NMR and mass spectrometry: MS m/e 223 (M-H)+; 1H NMR (400 MHz, DMSO-d6) δ 8.05 (dd, J=9.76,1.37Hz, 1H), 8.09 (d, J=8.08Hz, 1H), 8.29 (d, J=1.37Hz, 1H).