反应详情

1-(1-Methyl-2,2-diethoxyethyl)-4-carboxy-5-aminopyrazole (9.9 g) was dissolved in tetrahydrofuran (200 ml) and thereto was added 3N-hydrochloric acid (52 ml). The mixture was refluxed for 3 hours. The reaction mixture was cooled at room temperature, adjusted to pH 6 with aqueous 30% potassium carbonate and extracted with ethyl acetate (100 ml). Further the separated aqueous layer was extracted with ethyl acetate (50 ml). The organic layer was combined and dried over magnesium sulfate. The solvent was distilled off in vacuo. The residue was pulverized with isopropyl ether and the powder was collected by filtration to give 3-methyl-1H-imidazo[1,2-b]pyrazole (3.01 g).

1. temperatureThe mixture was refluxed for 3 hours
2. extractionextracted with ethyl acetate (100 ml)
3. extractionFurther the separated aqueous layer was extracted with ethyl acetate (50 ml)
4. dry with materialdried over magnesium sulfate
5. distillationThe solvent was distilled off in vacuo
6. filtrationthe powder was collected by filtration