Hydrogen Bromide → 2-bromo-1-(1-tert-butyl-1H-pyrazol-4-yl)-ethanone

HRID 2272971Notes

Reaction equation

HRID 2272971 reaction equation
[C:1]([N:5]1[CH:9]=[C:8]([C:10](=[O:12])[CH3:11])[CH:7]=[N:6]1)([CH3:4])([CH3:3])[CH3:2].[BrH:13].BrBr.S([O-])(O)=O.[Na+]>ClCCl.C(O)(=O)C>[Br:13][CH2:11][C:10]([C:8]1[CH:7]=[N:6][N:5]([C:1]([CH3:4])([CH3:3])[CH3:2])[CH:9]=1)=[O:12]

Participants

7

Reactant 4

HCID 260Hydrogen BromideHCID 24408Bromine2×HCID 23665763Sodium BisulfiteHCID 898263071460286-48-9

Product 1

HCID 898260822-bromo-1-(1-tert-butyl-1H-pyrazol-4-yl)-ethanone

Reagents, catalysts & solvents 2

HCID 176Acetic AcidSolventHCID 6344DichloromethaneSolvent2×

Procedure

To a solution of 1.66 g (10.0 mmol) 1-(1-tert-butyl-1H-pyrazol-4-yl)-ethanone in 18 ml dichloromethane is added 5.86 μl (0.10 mmol) of a 32% solution of hydrobromic acid in acetic acid. Then a solution of 3.20 g (20 mmol) bromine in 5 ml dichloromethane is added dropwise. The reaction mixture is stirred for 3 days at room temperature. Then aqueous sodium hydrogen sulfite is added to reduce the excess bromine. The reaction mixture is reduced in volume under vacuum and it is then partitioned between water and ethyl acetate. The organic phase is dried over sodium sulfate and evaporated. The residue is chromatographed on a silica gel column with cyclohexane/ethyl acetate as eluent to afford 2-bromo-1-(1-tert-butyl-1H-pyrazol-4-yl)-ethanone as yellow oil, which crystallizes on standing; HPLC/MS 2.28 min (B), [M+H] 245/247.

Workup

  1. customis then partitioned between water and ethyl acetate
  2. dry with materialThe organic phase is dried over sodium sulfate
  3. customevaporated
  4. customThe residue is chromatographed on a silica gel column with cyclohexane/ethyl acetate as eluent

Sources & evidence

ORD record
ord-cf924c7359c74c33ac9aec0c32eb07d4
Source dataset
uspto-grants-2015_09
Patent number
US09120805B2

Reaction notes

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