General procedure for the synthesis of 2,6-dibromobenzonitrile from 2,6-dibromoaniline and cuprous cyanide: 2,6-dibromoaniline (0.251 g, 1.00 mmol) was added to a stirred solution of cuprous(I) cyanide (0.116 g, 1.30 mmol) in dimethylsulfoxide (10 mL) under nitrogen protection and the temperature of the reaction was maintained at 50 °C. Subsequently, tert-butyl nitrite (0.357 mL, 3.00 mmol) was slowly added dropwise over 5 minutes and the reaction was continued with stirring at 50 °C for 1 hour. Upon completion of the reaction, the mixture was cooled to room temperature and quenched by pouring into 1 M aqueous hydrochloric acid (100 mL). The reaction mixture was extracted with ethyl acetate, and the organic phases were combined, washed sequentially with water and saturated brine, and then dried with anhydrous magnesium sulfate. The solvent was removed by concentration under reduced pressure and the resulting crude product was purified by silica gel column chromatography (eluent: 1-9% methanol/dichloromethane) to afford the target product 2,6-dibromobenzonitrile (0.100 g, 38% yield). The structure of the product was confirmed by 1H NMR (400 MHz, chloroform-d): δ 7.33 (t, J = 8.08 Hz, 1H), 7.67 (d, J = 8.08 Hz, 2H).
