反応 #1563938

反応方程式

NaNO2

3-(ethoxycarbonyl)-4-fluoropyrazolo[1,5-a]pyridin-5-aminium 2,2,2-trifluoroacetate

HBr

HBr

→

ethyl 5-bromo-4-fluoropyrazolo[1,5-a]pyridine-3-carboxylate

溶媒

water

反応条件

後処理

1. 1
   その他Reaction mixture
2. 2
   その他was quenched with ice water
3. 3
   抽出extracted into EtOAc
4. 4
   洗浄washed it with water
5. 5
   乾燥dried over anhydrous sodium sulphate
6. 6
   濃縮concentrated under reduced pressure
7. 7
   その他to afford crude
8. 8
   その他The crude obtained
9. 9
   その他was purified by column purification (using 60-120 silicagel and 5% EtOAc in Hexane as eluant)

実験手順

NaNO2 (2.26 g, 32.89 mmol) in water (7 mL) was added dropwise at 0° C. to a solution of 3-(ethoxycarbonyl)-4-fluoropyrazolo[1,5-a]pyridin-5-aminium 2,2,2-trifluoroacetate (7 g, 97.5 mmol) in aq.47% HBr (56 mL) and continued stirring at same temperature for 30 min. CuBr (6.29 g, 44 mmol) in aq. 47% HBr (56 mL) was added dropwise to above solution at 0° C. and stirring was continued at 28° C. for 1 hr. Reaction mixture was quenched with ice water, extracted into EtOAc, washed it with water followed by brine, dried over anhydrous sodium sulphate and concentrated under reduced pressure to afford crude. The crude obtained was purified by column purification (using 60-120 silicagel and 5% EtOAc in Hexane as eluant) to afford ethyl 5-bromo-4-fluoropyrazolo[1,5-a]pyridine-3-carboxylate. NMR (300 MHz, DMSO-d6) δ 9.45-9.43 (d, 1H), 8.51 (s, 1H), 8.33-8.30 (d, 1H), 4.35-4.28 (m, 2H), 1.36-1.31 (t, 3H).

出典