1305317-30-9

1232431-75-2

General procedure for the synthesis of 4-bromopyridine-2,3-diamine from 4-bromo-2-nitropyridin-3-amine: 4-bromo-2-nitropyridin-3-amine (1 g, 4.59 mmol) was dissolved in a solvent mixture of EtOH (20 mL) and water (5 mL) under stirring. To this solution, tin(IV) chloride (3.00 g, 11.52 mmol) was added slowly with the addition time controlled at 1 min. The reaction mixture was heated to 90°C and stirred at this temperature for 2 hours. After the reaction was completed, the mixture was cooled to room temperature and then carefully poured into saturated sodium bicarbonate solution (50 mL). The reaction mixture was extracted with dichloromethane (DCM, 2 x 100 mL). The organic phases were combined and washed sequentially with water (100 mL) and brine (100 mL). The organic layer was dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure to afford 4-bromopyridine-2,3-diamine (460 mg, 2.446 mmol, 53% yield) as a light brown solid. The resulting compound did not require further purification and could be used directly in the next step of the reaction.LCMS (ESI) m/z 187.9 [M+H]+ (calculated value C5H7BrN3, 187.91; measured value: 187.91).LC/MS retention time (Method C) tR=0.52 min.