反应详情

1.52 g of 6-chloro[1,2,4]triazolo[1,5-b]pyridazine-2-carboxylic acid and 1.45 ml of N-ethyldiisopropylamine were suspended in 15 ml of N,N-dimethylformamide; 1.37 g of N,N′-carbonyldiimidazole was added, followed by stirring at room temperature for 3 hours. To the reaction mixture, 1.41 g of 2-aminoisobutyric acid ethyl ester hydrochloride was added, followed by stirring at room temperature for 4 hour. Water was added, followed by extraction with ethyl acetate-tetrahydrofuran (1:1); the extract was washed with saturated saline and dried with magnesium sulfate. The dry product was concentrated under reduced pressure; the crystal precipitated was washed with ethyl ether, collected by filtration and dried to yield 1.48 g of the title compound. The filtrate was concentrated under reduced pressure; the residue was subjected to silica gel column chromatography and eluted with ethyl acetate. The desired fraction was collected and concentrated under reduced pressure to yield 450 mg of the title compound.

1. stirringby stirring at room temperature for 4 hour
2. extractionfollowed by extraction with ethyl acetate-tetrahydrofuran (1:1)
3. washthe extract was washed with saturated saline
4. dry with materialdried with magnesium sulfate
5. concentrationThe dry product was concentrated under reduced pressure
6. customthe crystal precipitated
7. washwas washed with ethyl ether
8. filtrationcollected by filtration
9. customdried