Step 4: To a sealed reaction tube was added 2,6-dichloro-4-[(1E)-2-(dimethylamino)vinyl]pyridine-3-carbonitrile (4.0 g, 16.6 mmol) and concentrated hydrochloric acid (20 mL). The reaction mixture was stirred at 45 °C for 18 hours. After completion of the reaction, it was cooled to room temperature and ice water was added to the reaction solution to form a yellow slurry. The precipitate was collected by filtration, washed sequentially with cold water, ether and ethyl acetate, and then dried under vacuum to afford 6,8-dichloro-2,7-naphthyridin-1(2H)-one as a pale yellow solid (80% yield). Mass spectrum (MS) m/z: 215.0 (M + 1). 1H NMR (300 MHz, DMSO-d6): δ 11.75 (s, 1H), 7.76 (s, 1H), 7.50 (t, J = 6.6 Hz, 1H), 6.52 (d, J = 6.6 Hz, 1H).
![3-Pyridinecarbonitrile, 2,6-dichloro-4-[(1E)-2-(dimethylamino)ethenyl]-](/CAS/20200611/GIF/1175559-53-1.gif)
