반응 #1563949

반응 방정식

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

용매

water

반응 조건

후처리

1. 1
   기타Reaction mixture
2. 2
   기타was quenched with ice water
3. 3
   추출extracted with ethyl acetate (3×50 mL)
4. 4
   세척washed it with water
5. 5
   건조dried over anhydrous sodium sulphate
6. 6
   농축concentrated under reduced pressure
7. 7
   기타to afford crude
8. 8
   기타The crude was purified by column purification (using silica gel and 0-5% ethyl acetate in Hexane as eluent)

실험 절차

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).

출처