4,7-dibroMo-5,6-difluorobenzo[c][1,2,5]thiadiazole

1345627-73-7

1295502-53-2

General procedure for the synthesis of 4,7-dibromo-5,6-difluorobenzo[c][1,2,5]thiadiazole (8) from 3,6-dibromo-4,5-difluorobenzene-1,2-diamine (7, 737 mg, 2.441 mmol): 3,6-dibromo-4,5-difluorobenzene-1,2-diamine was dissolved in 15 mL dichloromethane, triethylamine (1.36 mL , 9.76 mmol) and the mixed solution was cooled to 0°C (ice bath conditions). Thionyl chloride (0.36 mL) was added slowly by dropping through a dropping funnel, controlling the rate of dropping to maintain the reaction temperature. Upon completion of the dropwise addition, the reaction mixture was allowed to gradually warm up to room temperature and subsequently heated to 46 °C for 6 h at reflux. Upon completion of the reaction, the mixture was cooled to room temperature and poured into ice water. The pH was adjusted with dilute hydrochloric acid to about 1. The aqueous phase was extracted with dichloromethane, the organic layers were combined, washed with water and dried over anhydrous sodium sulfate. The solvent was removed by concentration under reduced pressure and the resulting crude product was purified by column chromatography to give compound 8 as white needle-like crystals in 88% yield.