Hydrogen Bromide → Ethyl 5-bromo-4-fluoropyrazolo[1,5-a]pyridine-3-carboxylate

HRID 926743Notes

Reaction equation

HRID 926743 reaction equation
N([O-])=O.[Na+].FC(F)(F)C([O-])=O.[CH2:12]([O:14][C:15]([C:17]1[CH:18]=[N:19][N:20]2[CH:25]=[CH:24][C:23]([NH3+])=[C:22]([F:27])[C:21]=12)=[O:16])[CH3:13].[BrH:28]>O>[Br:28][C:23]1[CH:24]=[CH:25][N:20]2[N:19]=[CH:18][C:17]([C:15]([O:14][CH2:12][CH3:13])=[O:16])=[C:21]2[C:22]=1[F:27]

Participants

5

Reactant 3

HCID 260Hydrogen Bromide2×HCID 23668193Sodium NitriteHCID 178469951HCID 178469951, compound

Product 1

HCID 89618488Ethyl 5-bromo-4-fluoropyrazolo[1,5-a]pyridine-3-carboxylate

Reagents, catalysts & solvents 1

HCID 962WaterSolvent

Procedure

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).

Workup

  1. customReaction mixture
  2. customwas quenched with ice water
  3. extractionextracted into EtOAc
  4. washwashed it with water
  5. dry with materialdried over anhydrous sodium sulphate
  6. concentrationconcentrated under reduced pressure
  7. customto afford crude
  8. customThe crude obtained
  9. customwas purified by column purification (using 60-120 silicagel and 5% EtOAc in Hexane as eluant)

Sources & evidence

ORD record
ord-17d34fa21b664e1d8b66168e69a3ff8b
Source dataset
uspto-grants-2016_03
Patent number
US09289419B2

Reaction notes

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