反应详情

To a stirred solution of 2-amino-5-bromo-benzoic acid (10.00 g, 46.38 mmol) in methanol (25 mL) was added methylamine (100 ml of 2 M solution in methanol), p-toluenesulfonic acid monohydrate (8.82 g, 46.38 mmol), and triethyl orthopropionate (40.87 g, 231.9 mmol). The reaction was refluxed for 18 hours, at which time it was allowed to cool to room temperature. The solution was concentrated under reduced pressure. The residue was partitioned between sodium carbonate aqueous (50 ml) and dichloromethane (50 ml). The organic layer was then washed with saturated brine (2×30 ml). The combined organic phase was dried over magnesium sulfate and filtered. The solvent was removed under vacuum. The resulting residue was purified by silica gel chromatography with 100% dichloromethane. The product was collected and was dried under reduced pressure to give 6-Bromo-2-ethyl-3-methyl-3H-quinazolin-4-one (Yield 4.92 g, 39.9%). 1H NMR (400 MHz, CDCl3): □ 1.42 (t, 3H, J=7.33 Hz), 2.86 (dd, 2H, J=14.65, 7.58 Hz), 7.45 (d, 1H, J=8.5 Hz), 7.80 (dd, 1H, J=8.50, 2.02 Hz), 8.40 (d, 1H, J=2.05 Hz). MS m/z calc. 266.01, found (ESI); 267.0 (M+1)+. Retention time 2.44 minutes.

1. temperatureThe reaction was refluxed for 18 hours, at which time it
2. concentrationThe solution was concentrated under reduced pressure
3. customThe residue was partitioned between sodium carbonate aqueous (50 ml) and dichloromethane (50 ml)
4. washThe organic layer was then washed with saturated brine (2×30 ml)
5. dry with materialThe combined organic phase was dried over magnesium sulfate
6. filtrationfiltered
7. customThe solvent was removed under vacuum
8. customThe resulting residue was purified by silica gel chromatography with 100% dichloromethane
9. customThe product was collected
10. customwas dried under reduced pressure