반응 #9854

반응 방정식

hexane

2-bromoethanol

3,5-dibromo-4-nitropyrazole

NaH

→

2-(3,5-dibromo-4-nitropyrazol-1-yl)ethanol

용매

DMF

DMF

DMF

반응 조건

후처리

1. 1
   기타the DMF was evaporated off under reduced pressure
2. 2
   workup.ADDITIONA mixture of DCM/water (100 ml, 1/1)
3. 3
   workup.ADDITIONis added to the residue
4. 4
   세척the organic phase is washed with water (50 ml)
5. 5
   건조The organic phase was dried over Na2SO4
6. 6
   기타the solvent was evaporated off under reduced pressure
7. 7
   기타The crude brown solid obtained
8. 8
   기타was subsequently purified by column chromatography (5%/95% EtOAc/hexane)
9. 9
   기타The yellow solid product (3.4 g) was recrystallized from a mixture of toluene/hexane (20 ml, 55%/45%)

실험 절차

A solution of 3,5-dibromo-4-nitropyrazole (2) (11.0 g, 41 mmol) in DMF (52 ml) was added dropwise over 20 min to a stirred solution of NaH (1.76 g, 46 mmol; 60% dispersion in oil, prewashed with hexane under an inert atmosphere) in DMF (88 ml). After stirring for 10 minutes, a solution of 2-bromoethanol (6.4 g, 49 mmol) in DMF (14 ml) was added dropwise over 10 minutes. The reaction mixture was heated to 80° C. for 2 hours and then the DMF was evaporated off under reduced pressure. A mixture of DCM/water (100 ml, 1/1) is added to the residue and the organic phase is washed with water (50 ml). The organic phase was dried over Na2SO4 and the solvent was evaporated off under reduced pressure. The crude brown solid obtained was subsequently purified by column chromatography (5%/95% EtOAc/hexane). The yellow solid product (3.4 g) was recrystallized from a mixture of toluene/hexane (20 ml, 55%/45%) to give the 2-(3,5-dibromo-4-nitropyrazol-1-yl)ethanol (3) in the form of a white solid (2.8 g, 22%).

출처