Methylamine → 6-Bromo-2-ethyl-3-methyl-3H-quinazolin-4-one

Participants

Reaction Steps

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.

Provenance & Evidence