Phosphorus oxychloride → Methyl 4,7-dichloroquinoline-2-carboxylate
Reaction equation
[CH3:1][O:2][C:3]([C:5]1[CH:14]=[C:13](O)[C:12]2[C:7](=[CH:8][C:9]([Cl:16])=[CH:10][CH:11]=2)[N:6]=1)=[O:4].O=P(Cl)(Cl)[Cl:19]>>[CH3:1][O:2][C:3]([C:5]1[CH:14]=[C:13]([Cl:19])[C:12]2[C:7](=[CH:8][C:9]([Cl:16])=[CH:10][CH:11]=2)[N:6]=1)=[O:4]Participants
3
Conditions
- Temperature
- 140 °C
Procedure
7-Chloro-4-hydroxy-2-quinolinecarboxylic acid methyl ester (76 g) was added to POCl3 (100 mL) at rt, and heated at 140 degrees C. for 1 h, then cooled to rt. After the removal of excess POCl3 in vacuo, cold 1 N NaOH solution was added to pH 8, and precipitated solid was triturated, washed with water and dried under vacuum to afford 78 g (95.2%) of 4,7-dichloro-2-quinolinecarboxylic acid methyl ester as an off-white powder. LC-MS, 255 (M++1). 1H NMR (DMSO-d6): δ 3.95 (s, 3H), 7.91 (d, 1H), 8.22 (s, 1H), 8.26 (d, 1H), 8.33 (s, 1H).