Reaktion #2446272

Reaktionsgleichung

3-(5-chloro-2-thienyl)-5-methyl-1H-pyrazole

N-Bromosuccinimide

sodium thiosulfate

sodium carbonate

→

4-bromo-3-(5-chloro-2-thienyl)-5-methyl-1H-pyrazole

Ausbeute 64.0%

Reaktionsbedingungen

Aufarbeitung

1. 1
   Trocknendry 1V, N-dim ethyl formamide
2. 2
   Temperaturto warm to room temperature
3. 3
   FiltrationThe precipitate was filtered
4. 4
   Waschenwashed thoroughly with water
5. 5
   workup.DISSOLUTIONdissolved in ethyl acetate
6. 6
   Trocknendried over MgSO4
7. 7
   Filtrationfiltered
8. 8
   Sonstigeevaporated

Vorschrift

3-(5-chloro-2-thienyl)-5-methyl-1H-pyrazole (111 mmol) was dissolved in 200 mL dry 1V, N-dim ethyl formamide and cooled to 0° C. under nitrogen atmosphere. N-Bromosuccinimide (118 mmol) was added in small portions at 0° C. The reaction mixture was allowed to warm to room temperature and was stirred overnight. The solution was poured into a mixture of saturated aqueous sodium thiosulfate solution and saturated aqueous sodium carbonate solution (1:1) at room temperature. The precipitate was filtered, washed thoroughly with water, dissolved in ethyl acetate, dried over MgSO4, filtered and evaporated to afford 19.5 g of 4-bromo-3-(5-chloro-2-thienyl)-5-methyl-1H-pyrazole (64% yield) that was used without further purification.

Quelle