反应详情

A mixture of 5.8 g of 4,9-dihydro-4-methyl-9-oxo-pyrazolo[5,1-b]quinazoline-2-carboxylic acid, ethyl ester, 50 ml of 1 N aqueous sodium hydroxide and 400 ml of methanol is heated at reflux until complete solution is attained (about 30 minutes). The solution is evaporated at reduced pressure to remove methanol; the residue is diluted with water and acidified with 1 N hydrochloric acid. The resulting precipitate is 4,9-dihydro-4-methyl-9-oxo-pyrazolo[5,1-b]quinazoline-2-carboxylic acid is collected by filtration, washed with water and dried; mp 265° C., after crystallization from dimethylformamide/methanol.

1. temperatureis heated
2. temperatureat reflux until complete solution
3. custom(about 30 minutes)
4. customThe solution is evaporated at reduced pressure
5. customto remove methanol
6. additionthe residue is diluted with water
7. filtrationis collected by filtration
8. washwashed with water
9. customdried
10. custommp 265° C., after crystallization from dimethylformamide/methanol