反应详情

18.1 ml of 1.6M n-butyl lithium in hexane are added to a tetrahydrofuran solution of 3.56 g of 1-ethoxymethylpyrazole at -55° to -53° C. under argon gas atmosphere and the mixture is stirred at the same temperature for 1 hour. A solution of 2.45 g of 2,3-dichloro-4-hydroxybenzaldehyde in tetrahydrofuran is added to the above mixture, and the reaction mixture is stirred at -55° to -60° C. for 3 hours. 4.9 ml of hexamethylphosphoric triamide are then added and the whole mixture is stirred at room temperature for 16 hours. An aqueous saturated ammonium chloride solution is added and the mixture is extracted with ethyl acetate. The extract is washed with water, dried and evaporated to remove solvent. The residue is purified by silica gel column chromatography and crystallized with a mixture of ethyl acetate and isopropyl ether to give 2.69 g of α-(1-ethoxymethyl-5-pyrazolyl)-2,3-dichloro-4-hydroxybenzylalcohol.

1. stirringthe reaction mixture is stirred at -55° to -60° C. for 3 hours
2. stirringthe whole mixture is stirred at room temperature for 16 hours
3. extractionthe mixture is extracted with ethyl acetate
4. washThe extract is washed with water
5. customdried
6. customevaporated
7. customto remove solvent
8. customThe residue is purified by silica gel column chromatography
9. customcrystallized with a mixture of ethyl acetate and isopropyl ether