Phosphorus oxychloride → 7-Bromo-2-chloro-1,5-naphthyridine
Reaction equation
[Br:1][C:2]1[CH:11]=[C:10]2[C:5]([CH:6]=[CH:7][C:8](=O)[NH:9]2)=[N:4][CH:3]=1.O=P(Cl)(Cl)[Cl:15]>>[Br:1][C:2]1[CH:11]=[C:10]2[C:5]([CH:6]=[CH:7][C:8]([Cl:15])=[N:9]2)=[N:4][CH:3]=1Participants
3
Procedure
7-bromo-1,5-naphthyridin-2(1H)-one (C-4) (3.1 g, 13.78 mmol, 1.0 eq) was dissolved in POCl3 (20 mL) and the resulting mixture was stirred at reflux for 1 h. The reaction was complete based on TLC analysis. The mixture was concentrated in vacuo to remove POCl3. The residue was poured into ice water (30 mL) and neutralized with saturated aqueous Na2CO3 solution to adjust the pH value to 7-8 while keeping the temperature below 10° C. The resulting mixture was extracted with ethyl acetate (3×30 mL), the combined organic layer was washed with brine, dried over Na2SO4 and filtered. The filtrate was concentrated in vacuo to afford the desired product 7-bromo-2-chloro-1,5-naphthyridine (F-31) (2.11 g, 62.9% yield). ESI-MS m/z: 242.9 [M+H]+.