131998-24-8

199983-20-5

131998-24-8

7-Amino-1,8-diazanaphthalene-2,4-diol (Compound 1.1, 7.00 g, 39.5 mmol) was suspended in acetic anhydride (80 mL) and heated to reflux for 18 hours as starting material. Upon completion of the reaction, it was cooled to room temperature, the solid product was collected by filtration, washed with water, and dried under reduced pressure to give a yellow solid intermediate (7.11 g), which was shown by mass spectrometry (ES+) to be m/z 220 ([M+H]+). Subsequently, the intermediate solid was suspended in phosphorus oxychloride (POCl3, 55 mL) and reacted at reflux for 2 hours. At the end of the reaction, the solvent was evaporated under reduced pressure and the residue was carefully poured into an ice/water mixture (400 mL) to quench. The resulting mixture was heated to near boiling state and kept for 5 h. After cooling, the black solid was removed by filtration. The filtrate was carefully adjusted to neutral (pH ≈ 7) with 2 M aqueous sodium hydroxide. The precipitated solid was collected by filtration, washed with water and dried under reduced pressure to afford the target product 5,7-dichloro-1,8-naphthyridin-2-amine (Compound 1.2, 4.03 g, 48% yield), which was shown by mass spectrum (ES+) to be m/z 214 ([M+H]+).