反应详情

3-Chloro-6-hydrazinopyridazine (1.59 g) and the 4-(2-pyridyl)-2,4-dioxobutanoic acid ethyl ester (2.45 g) obtained from Referential Example 31 in ethanol (60 mL) was refluxed under heat for 6 hours. To the reaction mixture, concentrated hydrochloric acid (1 mL) was added, and the mixture was refluxed under heat for 1 hour, and then cooled in air. The reaction solvent was removed under reduced pressure, and the residue was partitioned by use of ethyl acetate and saturated aqueous sodium hydrogencarbonate. The organic layer was washed with saturated brine, and then dried over magnesium sulfate anhydrate, followed by filtration. The solvent was removed under reduced pressure, and the residue was purified through silica gel chromatography (ethyl acetate-hexane), to thereby give 1-(6-chloro-3-pyridazinyl)-5-(2-pyridyl)pyrazole-3-carboxylic acid ethyl ester as a solid (1.50 g, 41%).

1. temperaturewas refluxed
2. temperatureunder heat for 6 hours
3. temperaturethe mixture was refluxed
4. temperatureunder heat for 1 hour
5. temperaturecooled in air
6. customThe reaction solvent was removed under reduced pressure
7. customthe residue was partitioned by use of ethyl acetate and saturated aqueous sodium hydrogencarbonate
8. washThe organic layer was washed with saturated brine
9. dry with materialdried over magnesium sulfate anhydrate
10. filtrationfollowed by filtration
11. customThe solvent was removed under reduced pressure
12. customthe residue was purified through silica gel chromatography (ethyl acetate-hexane)