反应详情

A suspension of 2-amino-4-bromo-5-fluorobenzoic acid (10.0 g, 42.7 mmol) in a mixture of 37% aqueous HCl (42.7 mL) and water (14.3 mL), cooled with a NaCl -ice bath, was treated dropwise with a solution of sodium nitrite (3.24 g, 47.0 mmol) in water (15.7 mL). When addition was complete, the mixture was stirred for 30 min more. A solution of tin(II) chloride dihydrate (28.9 g, 128 mmol) in 37% aqueous HCl (27.5 mL) was added dropwise. The cooling bath was removed and the mixture was stirred at room temperature for 45 min. The thick suspension was filtered and the collected precipitate was washed thoroughly with water and dried overnight under reduced pressure. The solid was triturated with MeOH with sonication, and the precipitate was collected by filtration, washed with MeOH and dried. The filtrate was concentrated, and the residue was triturated with DCM. The resulting solid was collected by filtration, dried and combined with the other solid to give 4-bromo-5-fluoro-2-hydrazinylbenzoic acid hydrochloride (5.37 g, 44% yield) as a white solid. Mass spectrum m/z 249, 251 (M+H)+.

1. temperaturecooled with a NaCl -ice bath
2. additionWhen addition
3. customThe cooling bath was removed
4. stirringthe mixture was stirred at room temperature for 45 min
5. filtrationThe thick suspension was filtered
6. washthe collected precipitate was washed thoroughly with water
7. customdried overnight under reduced pressure
8. customThe solid was triturated with MeOH with sonication
9. filtrationthe precipitate was collected by filtration
10. washwashed with MeOH
11. customdried
12. concentrationThe filtrate was concentrated
13. customthe residue was triturated with DCM
14. filtrationThe resulting solid was collected by filtration
15. customdried