Bromine → 3-Bromo-2-ethyl-4,5,6,7-tetrahydropyrazolo[1,5-a]pyridine
Reaction equation
[CH2:1]([C:3]1[CH:11]=[C:6]2[CH2:7][CH2:8][CH2:9][CH2:10][N:5]2[N:4]=1)[CH3:2].[Br:12]Br>CCO>[Br:12][C:11]1[C:3]([CH2:1][CH3:2])=[N:4][N:5]2[CH2:10][CH2:9][CH2:8][CH2:7][C:6]=12Participants
4
Reactant 2
Product 1
Reagents, catalysts & solvents 1
Conditions
- Temperature
- 0 °C
Procedure
To a solution of 2-ethyl-4,5,6,7-tetrahydropyrazolo[1,5-α]pyridine (4.12 g, from Step 2) in EtOH (25 mL) was added Br2 (1.42 mL) dropwise at 0° C. The reaction was stirred at 0° C. for 20 min. The reaction mixture was partitioned between EtOAc and aqueous NaHCO3 (saturated). Aqueous layer was extracted with EtOAc (3×). Combined organic phase was washed with brine and dried over anhydrous MgSO4. After concentration, the residue was purified by flash chromatography with 10% EtOAc in hexanes followed by 20% EtOAc in hexanes to give the title compound as a viscous oil. 1H NMR (500 MHz, CDCl3) δ 1.25 (t, 3H, J=7.5 Hz), 1.80-1.90 (m, 2H), 1.95-2.05 (m, 2H), 2.55-2.70 (m, 4H), 4.07 (t, 2H, J=6.0 Hz).
Workup
- customThe reaction mixture was partitioned between EtOAc and aqueous NaHCO3 (saturated)
- extractionAqueous layer was extracted with EtOAc (3×)
- washCombined organic phase was washed with brine
- dry with materialdried over anhydrous MgSO4
- concentrationAfter concentration
- customthe residue was purified by flash chromatography with 10% EtOAc in hexanes
Sources & evidence
- ORD record
- ord-9f9e7f9a3012464680401c9c83aa8492
- Source dataset
- uspto-grants-2003_01
- Patent number
- US06511994B2
Reaction notes
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