58633-04-8

873-74-5

58633-04-8

Preparation of Example 25 4-amino-3,5-dibromobenzonitrile (STR37): To a stirred solution of 100 mg (0.847 mmol) of p-aminobenzonitrile dissolved in 3.6 mL of dioxane was sequentially added 356 μL (1.78 mmol) of 5N sodium hydroxide solution and an appropriate amount (1.78 mmol) of bromine under ice-bath cooling conditions. After removing the ice water bath, the reaction mixture was continued to stir for 1.5 hours. Subsequently, 21.8 μL (0.423 mmol) of bromine was added to ensure that the reaction was complete and stirring was continued for 10 minutes. The reaction mixture was partitioned with ethyl acetate and ice water to separate the organic phase. The organic phase was sequentially washed with brine, dried over anhydrous sodium sulfate, filtered and concentrated. Purification by silica gel plate chromatography using hexane-ethyl acetate (7:3, v/v) as eluent gave 175 mg (74%) of the target product 4-amino-3,5-dibromobenzonitrile. The product was characterized by NMR (CDCl3): δ 5.1 (broad peak, 2H), 7.66 (single peak, 2H).