957193-64-5

957193-63-4

957193-64-5

Example 2. Synthesis of 7-iodo-3,4-dihydro-1H-pyrido[2,3-b]pyrazin-2-one: Ethyl (5-iodo-3-nitropyridin-2-yl)glycinate (17 g) was dissolved in ethanol. SnCl2-2H2O was added to the solution and the reaction mixture was heated to 80 °C and kept for two hours. After completion of the reaction, the resulting precipitate was collected by filtration and washed with ethanol to afford 7-iodo-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one as a rust-colored solid in 59-77% yield. The melting point was 81 °C. LCMS analysis showed m/z = 275.91 ([M+H]+).1H-NMR (DMSO-d6, 400 MHz) δ 3.94 (s, 2H), 6.94 (bs, 1H), 7.12 (d, J = 1.8 Hz, 1H), 7.74 (d, J = 1.8 Hz, 1H), 10.40 (bs, 1H) .