反应详情

Ethyl 3-n-propylpyrazole-5-carboxylate (1.7 g, 9.1 mmol), 2-bromo-5-bromomethylpyridine (4.6 g, 9.1 mmol) and potassium carbonate (1.8 g, 12.7 mmol) were dissolved in DMF (70.0 mL, 904 mmol). The resulting suspension was stirred at room temperature overnight. The material was diluted with aqueous. NaHCO3 and diethyl ether. The aqueous layer was further extracted with diethyl ether. The combined organics were dried over MgSO4, filtered and concentrated. The residue was purified using flash chromatography [1st 30:1 hexanes/EtOAc; 2nd 10:1 hexanes/EtOAc]. The two isomers were separated and analyzed by NMR and NOE: 1-(6-bromopyridin-3-ylmethyl)-5-propyl-1H-pyrazole-3-carboxylic acid ethyl ester (1.2 g) and 2-(6-bromopyridin-3-ylmethyl)-5-propyl-2H-pyrazole-3-carboxylic acid ethyl ester.

1. additionThe material was diluted with aqueous
2. extractionThe aqueous layer was further extracted with diethyl ether
3. dry with materialThe combined organics were dried over MgSO4
4. filtrationfiltered
5. concentrationconcentrated
6. customThe residue was purified
7. customThe two isomers were separated