反应详情

To a solution of pyridazine-4-carboxylic acid (Aldrich, 5.0 g, 40.3 mmol) in methanol (anhydrous, Aldrich, 100 mL) was added sulfuric acid (concentrated, Aldrich, 2 mL). The reaction mixture was then heated to reflux and stirred for 16 hours. The volatiles were removed under reduced pressure. The residue was basified to pH=8-9 with saturated sodium carbonate (20 mL) and then extracted with EtOAc (3×100 mL). The combined extracts were washed with brine (2×20 mL) and dried over magnesium sulfate. The drying agent was filtered off and the organic solution was concentrated and dried to give the titled compound. 1H NMR (300 MHz, DMSO-d6) δ 3.34 (s, 3 H), 8.10 (dd, J=5.2, 2.4 Hz, 1 H), 9.52 (dd, J=5.2, 1.2 Hz, 1 H), 9.58 (dd, J=2.2, 1.4 Hz, 1 H) ppm; MS (DCI/NH3) m/z 139 (M+H)+.

1. temperatureThe reaction mixture was then heated
2. temperatureto reflux
3. customThe volatiles were removed under reduced pressure
4. extractionextracted with EtOAc (3×100 mL)
5. washThe combined extracts were washed with brine (2×20 mL)
6. dry with materialdried over magnesium sulfate
7. filtrationThe drying agent was filtered off
8. concentrationthe organic solution was concentrated
9. customdried