4-Bromo-2,5-dimethylbenzene-1-sulfonamide → 4-Cyano-2,5-dimethylbenzenesulfonamide

To a solution of 4-bromo-2,5-dimethylbenzenesulfonamide (4.6 g, 22 mmol, the product of Step A) in N-methylpyrrolidinone (30 mL) was added copper cyanide (2.5 g, 28 mmol), and the reaction mixture was heated at 200° C. for 30 min. The reaction was then allowed to cool and poured into 200 mL of crushed ice to precipitate a solid. To this mixture was added dichloromethane (500 mL), and the mixture was warmed to dissolve the white solid. The mixture was then filtered to remove any undissolved solids, the phases were separated, and the dichloromethane was washed with water (2×100 mL), dried over magnesium sulfate, and evaporated under reduced pressure to obtain an oil. The oil was dissolved in tetrahydrofuran (30 mL) and water (30 mL), and the solution was concentrated under reduced pressure to precipitate a solid. This solid was isolated by filtration and washed with water to afford 2.5 g of the title compound. 1H NMR (CDCl3) δ 7.98 (s, 1H), 7.56 (s, 1H), 4.89 (br s, 2H), 2.66 (s, 3H), 2.58 (s, 3H).