[Br:1][C:2]1[CH:11]=[C:10]2[C:5]([C:6](=[O:17])[C:7]([C:12]([O:14]CC)=[O:13])=[CH:8][NH:9]2)=[N:4][CH:3]=1.[OH-].[Na+].C>O>[Br:1][C:2]1[CH:11]=[C:10]2[C:5]([C:6]([OH:17])=[C:7]([C:12]([OH:14])=[O:13])[CH:8]=[N:9]2)=[N:4][CH:3]=1Ethyl 7-bromo-4-oxo-1,4-dihydro-1,5-naphthyridine-3-carboxylate (1 g, 3 mmol) and 2.5 M NaOH (10 mL) were refluxed for 1 h in a RBF fitted with a reflux condenser. The hot, heterogeneous mixture was diluted with boiling water at which point a tan precipitate dissolved. Charcoal was added to the solution, which was swirled for 2 min and then the mixture was filtered. Glacial acetic acid was added to the filtrate and a white precipitate started to form (pH adjusted to 4). The precipitate was filtered off upon cooling, washed with water and dried to provide the desired product as a white solid.
불러오는 중…