Sodium Hydroxide → 4,9-Dihydro-4-methyl-9-oxo-pyrazolo[5,1-b]quinazoline-2-carboxylic Acid
Reaction equation
[CH3:1][N:2]1[C:11]2[CH:10]=[CH:9][CH:8]=[CH:7][C:6]=2[C:5](=[O:12])[N:4]2[N:13]=[C:14]([C:16]([O:18]CC)=[O:17])[CH:15]=[C:3]12.[OH-].[Na+]>CO>[CH3:1][N:2]1[C:11]2[CH:10]=[CH:9][CH:8]=[CH:7][C:6]=2[C:5](=[O:12])[N:4]2[N:13]=[C:14]([C:16]([OH:18])=[O:17])[CH:15]=[C:3]12Participants
4
Procedure
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.