Phosphorus oxychloride → 4,8-dichloro-6-methylbenzo[c][2,7]naphthyridin-5(6H)-one
Reaction equation
[Cl:1][C:2]1[CH:3]=[CH:4][C:5]2[C:14]3[C:9](=[CH:10][N+:11]([O-])=[CH:12][CH:13]=3)[C:8](=[O:16])[N:7]([CH3:17])[C:6]=2[CH:18]=1.O=P(Cl)(Cl)[Cl:21]>>[Cl:21][C:10]1[N:11]=[CH:12][CH:13]=[C:14]2[C:9]=1[C:8](=[O:16])[N:7]([CH3:17])[C:6]1[CH:18]=[C:2]([Cl:1])[CH:3]=[CH:4][C:5]2=1Participants
3
Procedure
A stirred solution of 8-chloro-6-methyl-5-oxo-5,6-dihydrobenzo[c][2,7]naphthyridine 3-oxide (0.5 g, 1.918 mmol) in POCl3 (3.58 mL, 38.4 mmol) was heated to reflux for 6 h. The reaction mixture was concentrated under reduced pressure. The residue was then partitioned between dichloromethane (100 mL) and saturated sodium bicarbonate solution (200 mL). The organic layer was separated and washed again with brine solution (50 mL), dried over sodium sulphate, and concentrated to afford 4,8-dichloro-6 methylbenzo[c][2,7]naphthyridin-5(6H)-one (0.3 g, 1.075 mmol, 56% crude yield). The material was carried on without further purification. LC/MS (ESI) m/e 280.8, [(M+2H)+, calcd for C13H9Cl2N2O, 280.8]; LC/MS retention time (method C): tR=2.06 min.