反应详情

温度

-30 °C

To a suspension of 1-ethyl-4-oxo-1,4-dihydro-[1,3]dioxolo[4,5-g]cinnoline-3-carboxylic acid (12.6 g, 48.1 mmol) in dichloromethane (DCM) (50 mL) stirred under nitrogen at −30° C. was added dropwise a solution of boron tribromide (168 mL, 168 mmol) in dichloromethane (140 mL). The white suspension turned yellowish. The mixture was kept at −30° C. for 1 h and then allowed to warm up to room temperature, and stirred for 40 h. The reaction mixture was again cooled to −30° C., methanol (100 mL) was added, and the resulting mixture was stirred at room temperature over the weekend. The organic solvents were partially removed to afford a light yellow suspension. The solid was collected by filtration and washed with dichloromethane (20 mL). The filtrate was concentrated again to provide more yellow solids that was collected and washed by dichloromethane (20 mL). The solids were combined to afford methyl 1-ethyl-6,7-dihydroxy-4-oxo-1,4-dihydrocinnoline-3-carboxylate (11 g, 35.8 mmol, 74.5% yield). LCMS: (M+H)+: 265.0

1. temperatureto warm up to room temperature
2. stirringstirred for 40 h
3. temperatureThe reaction mixture was again cooled to −30° C.
4. stirringthe resulting mixture was stirred at room temperature over the weekend
5. customThe organic solvents were partially removed
6. customto afford a light yellow suspension
7. filtrationThe solid was collected by filtration
8. washwashed with dichloromethane (20 mL)
9. concentrationThe filtrate was concentrated again
10. customto provide more yellow solids that
11. customwas collected
12. washwashed by dichloromethane (20 mL)