Bromine → 3-bromo-2-phenyl-6,7-dihydro-5H-pyrazolo[5,1-b][1,3]oxazine

HRID 570132Notes

Reaction equation

HRID 570132 reaction equation
[C:1]1([C:7]2[CH:15]=[C:10]3[O:11][CH2:12][CH2:13][CH2:14][N:9]3[N:8]=2)[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1.[Br:16]Br.S([O-])([O-])(=O)=S.[Na+].[Na+]>C(Cl)(Cl)Cl>[Br:16][C:15]1[C:7]([C:1]2[CH:2]=[CH:3][CH:4]=[CH:5][CH:6]=2)=[N:8][N:9]2[CH2:14][CH2:13][CH2:12][O:11][C:10]=12

Participants

5

Reactant 3

HCID 24408BromineHCID 24477Sodium ThiosulfateHCID 894883542-phenyl-6,7-dihydro-5H-pyrazolo[5,1-b][1,3]oxazine

Product 1

HCID 894883513-bromo-2-phenyl-6,7-dihydro-5H-pyrazolo[5,1-b][1,3]oxazine

Reagents, catalysts & solvents 1

HCID 6212ChloroformSolvent2×

Procedure

To a solution of 2-phenyl-6,7-dihydro-5H-pyrazolo[5,1-b][1,3]oxazine (6.3 g, 0.031 mol) in 60 mL chloroform is added a solution of bromine (1 eq, 5.03 g, 0.031 mol) in 40 mL chloroform over a period of 25 min at room temperature. The resulting suspension is stirred for 4 h at room temperature. Thereafter the reaction mixture is treated with aqueous sodium thiosulfate, the phases are separated and the organic phase is washed with water and dried over sodium sulfate. The volatiles are evaporated and the crude product is purified by filtration over silica using a 1:1 mixture of ethyl acetate/cyclohexane as eluent. After evaporation of the solvent 7.0 g (90%) of 3-bromo-2-phenyl-6,7-dihydro-5H-pyrazolo[5,1-b][1,3]oxazine are obtained as solid.

Workup

  1. customthe phases are separated
  2. washthe organic phase is washed with water
  3. dry with materialdried over sodium sulfate
  4. customThe volatiles are evaporated
  5. filtrationthe crude product is purified by filtration over silica using
  6. additiona 1:1 mixture of ethyl acetate/cyclohexane as eluent
  7. customAfter evaporation of the solvent 7.0 g (90%) of 3-bromo-2-phenyl-6,7-dihydro-5H-pyrazolo[5,1-b][1,3]oxazine
  8. customare obtained as solid

Sources & evidence

ORD record
ord-a11bc9ea5a9443439a3775cfd7ff8d84
Source dataset
uspto-grants-2015_05
Patent number
US09023844B2

Reaction notes

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