Реакция #1563949

Уравнение реакции

HBr

NaNO2

7-fluoro-2,3-dihydrobenzo[b][1,4]dioxin-5-amine

HBr

→

5-bromo-7-fluoro-2,3-dihydrobenzo[b][1,4]dioxine

Растворители

water

Условия реакции

Обработка

1. 1
   ДругоеReaction mixture
2. 2
   Другоеwas quenched with ice water
3. 3
   Экстракцияextracted with ethyl acetate (3×50 mL)
4. 4
   Промывкаwashed it with water
5. 5
   Сушкаdried over anhydrous sodium sulphate
6. 6
   Концентрированиеconcentrated under reduced pressure
7. 7
   Другоеto afford crude
8. 8
   ДругоеThe crude was purified by column purification (using silica gel and 0-5% ethyl acetate in Hexane as eluent)

Методика

NaNO2 (2.69 g, 39.9 mmol) in water (20 mL) was added slowly at 0° C. to a solution of 7-fluoro-2,3-dihydrobenzo[b][1,4]dioxin-5-amine (4.5 g, 26 mmol) in aq.47% HBr (20 mL) and continued stirring at same temperature for 30 min. The above diazonium salt solution was added slowly to a solution of CuBr (5.7 g, 39.9 mmol) in aq.47% HBr (25 mL) at 0° C. and stirred at 25° C. for 30 min. Reaction mixture was quenched with ice water, extracted with ethyl acetate (3×50 mL), washed it with water followed by brine, dried over anhydrous sodium sulphate and concentrated under reduced pressure to afford crude. The crude was purified by column purification (using silica gel and 0-5% ethyl acetate in Hexane as eluent) to afford 5-bromo-7-fluoro-2,3-dihydrobenzo[b][1,4]dioxine (Int-53) (5.9 g). 1H NMR (300 MHz, CDCl3) δ ppm 6.9-6.84 (1H, dd), 6.6-6.5 (1H, dd), 4.3-4.3 (4H, m).

Источник