N-bromobutanimide → methyl 5-(bromomethyl)-1-methyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazole-4-carboxylate

HRID 415884Notes

Reaction equation

HRID 415884 reaction equation
[CH3:1][N:2]1[C:6]([CH3:7])=[C:5]([C:8]([O:10][CH3:11])=[O:9])[C:4](=[O:12])[N:3]1[C:13]1[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=1.C1C(=O)N([Br:26])C(=O)C1>C(Cl)(Cl)Cl>[Br:26][CH2:7][C:6]1[N:2]([CH3:1])[N:3]([C:13]2[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=2)[C:4](=[O:12])[C:5]=1[C:8]([O:10][CH3:11])=[O:9]

Participants

4

Reactant 2

HCID 67184N-bromobutanimide2×HCID 20294053methyl 1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazole-4-carboxylate

Product 1

HCID 59598414methyl 5-(bromomethyl)-1-methyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazole-4-carboxylateYield 33%

Reagents, catalysts & solvents 1

HCID 6212ChloroformSolvent

Procedure

Methyl 1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazole-4-carboxylate (7.82 g, 31.8 mmol) was dissolved in CHCl3 (150 ml) and n-bromosuccimide (6.91 g, 38.8 mmol) was added. The reaction was stirred at room temperature, and after 1.5 hours, more NBS (6.23 g, 35.2 mmol) was added. After another hour of stirring, the reaction was filtered, and the solid was washed with chloroform. The filtrate was concentrated, treated with dichlormethane, and refiltered. The filtrate was again concentrated, and filtered through silica gel (˜3 inches, dichlormethane/MeOH). The fractions with product collected, concentrated, and purified on silica gel (dichlormethane/MeOH) to give the desired methyl 5-(bromomethyl)-1-methyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazole-4-carboxylate (4.11 g, 82% purity, 10.4 mmol, 33% yield). MS (ESI pos. ion) m/z: 325, 327 (MH+). Calc'd exact mass for C13H13Br79.0N2O3: 324. Calc'd exact mass for C13H13Br81.0N2O3: 326.

Workup

  1. stirringAfter another hour of stirring
  2. filtrationthe reaction was filtered
  3. washthe solid was washed with chloroform
  4. concentrationThe filtrate was concentrated
  5. additiontreated with dichlormethane
  6. concentrationThe filtrate was again concentrated
  7. filtrationfiltered through silica gel (˜3 inches, dichlormethane/MeOH)
  8. customThe fractions with product collected
  9. concentrationconcentrated
  10. custompurified on silica gel (dichlormethane/MeOH)

Sources & evidence

ORD record
ord-b387ecd38a724ebf99727882ea06d72a
Source dataset
uspto-grants-2012_01
Patent number
US08088794B2

Reaction notes

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