Boronic acid, (5-cyano-2-methoxyphenyl)- (9CI)

5419-55-6

117572-79-9

612833-37-1

The general procedure for the synthesis of 2-methoxy-5-cyanophenylboronic acid from triisopropyl borate and 3-bromo-4-methoxybenzonitrile was as follows: firstly, 3-bromo-4-methoxybenzonitrile (7.7 g, 36 mmol) and triisopropyl borate (14 g, 73 mmol) were dissolved in tetrahydrofuran (150 mL), and then at -78 °C, 2.5 mol/L of n butyl lithium (hexane solution, 22 mL, 55 mmol), and the addition process lasted for 20 min. After the reaction mixture was stirred at -78 °C for 2 h, 7% phosphoric acid (100 mL) was added and the mixture was gradually warmed to room temperature. Subsequently, the reaction mixture was partitioned by adding dichloromethane to the organic layer and extracting the mixture with 5% aqueous sodium hydroxide (200 mL). The aqueous layer was washed with ether and adjusted to pH 2.5 with 85% phosphoric acid and the insoluble material was collected by filtration. The resulting solid was washed with water and dried to give the final 2-methoxy-5-cyanophenylboronic acid (5.1 g, 29 mmol, 79% yield). The product was detected by mass spectrometry (ESI) at m/z 178 (M+H)+; 1H NMR (300 MHz, DMSO-d6) δ 8.03 (s, 2H), 7.86-7.78 (m, 2H), 7.13 (d, J=11.6 Hz, 1H), 3.85 (s, 3H).