反应详情

Potassium t-Butyl alcohol (29.25 g, 260.68 mmol) is added to a solution of 3-methyl-1H-pyrazole-4-carbaldehyde (26.00 g, 236.12 mmol) in dimethylformamide (250 mL) cooled with an aqueous bath. The mixture is stirred at room temperature for 10 min. Then, 2,3-difluoropyridine (25 g, 217.24 mmol) is added and the mixture is stirred at room temperature for 20 hr. The mixture is poured over an ice/water mixture and extracted in ethyl acetate (3×20 mL). Organics are dried over magnesium sulfate and solvent evaporated in vacuo. The residue is purified by silica gel chromatography using as eluent hexane/isopropyl alcohol to afford a crude material with residual dimethylformamide. The material is then dissolved in ethyl acetate (100 mL) and washed with water (3×20 mL). Aqueous phase is extracted with ethyl acetate (2×20 mL). Combined organics are dried over sodium sulfate and concentrated to give 19 g of the title compound. MS (m/z): 206 (M+1).

1. temperaturecooled with an aqueous bath
2. stirringthe mixture is stirred at room temperature for 20 hr
3. extractionextracted in ethyl acetate (3×20 mL)
4. dry with materialOrganics are dried over magnesium sulfate and solvent
5. customevaporated in vacuo
6. customThe residue is purified by silica gel chromatography
7. customto afford a crude material with residual dimethylformamide
8. washwashed with water (3×20 mL)
9. extractionAqueous phase is extracted with ethyl acetate (2×20 mL)
10. dry with materialCombined organics are dried over sodium sulfate
11. concentrationconcentrated