Réaction #657314

Équation de réaction

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

bromine

sodium thiosulfate

→

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

Solvants

chloroform

chloroform

Conditions de réaction

Traitement

1. 1
   Autrethe phases are separated
2. 2
   Lavagethe organic phase is washed with water
3. 3
   Séchagedried over sodium sulfate
4. 4
   AutreThe volatiles are evaporated
5. 5
   Filtrationthe crude product is purified by filtration over silica using
6. 6
   workup.ADDITIONa 1:1 mixture of ethyl acetate/cyclohexane as eluent
7. 7
   AutreAfter 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. 8
   Autreare obtained as solid

Mode opératoire

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.

Source