The general procedure for the synthesis of 5-bromo-2-cyanophenylacetonitrile from 4-bromo-2-fluorobenzonitrile and methyl cyanoacetate was carried out as follows: first, sodium hydride (47.2 g, 1.18 mol) was suspended in 320 mL of dimethylsulfoxide (DMSO) and cooled to 0°C in an ice-water bath. The mixture gradually became viscous as the DMSO began to freeze. Subsequently, methyl cyanoacetate (104 mL, 1.18 mol) was slowly added, a process that caused a slight temperature increase, thus making the mixture easier to stir. The reaction mixture was stirred at room temperature for 30 minutes. Next, a solution of 4-bromo-2-fluorobenzonitrile (118 g, 590 mmol, commercially available from Acros Organics, Order No. 29049) in 500 mL of DMSO was added to the reaction system via cannula. The mixture was heated to an internal temperature of 90°C. After the reaction was complete, the mixture was cooled and allowed to stand overnight. 1.2 L of water was added to the reaction mixture and heated to an internal temperature of 104 °C over 3 hours. Another 2.3 L of water was added and the mixture was heated to reflux for 16 hours. After that, the mixture was cooled to 5 °C and 0.2 N hydrochloric acid (700 mL) was added and stirred at 5 °C for 30 min. The resulting precipitate was filtered, washed with water and dried to give the final target product 4-bromo-2-(cyanomethyl)benzonitrile (102 g, 78% yield). The product was analyzed by LCMS (API-ES), m/z: 223,221 ([M-H]+).
