Acetic Acid → 5,6-Dimethoxy-3-methylquinazolin-2,4(1H, 3H)-dione

Participants

Reaction Conditions

Reaction Steps

A cold solution of ethyl 2,3-dimethoxy-6-aminobenzoate (8.0 g, 35.5 mM) in pyridine (15.4 ml) was added to CH3NCO (3.2 g, 55.9 mM) in pyridine (11.5 ml) at 0° C. The solution was stirred at 0° C. for 30 minutes then at room temperature for 1 hour. The reaction mixture was concentrated to dryness. The resulting brown gummy residue was dissolved in 73 ml of 1N NaOH (4:1, MeOH: H2O, 2.9 g of NaOH pellets in 14.7 ml H2O and 58.3 ml MeOH) and refluxed for 2 hours. The solvent was removed in vacuo to give a light brown solid. This was dissolved in H2O (180 ml) and the pH adjusted to 5 with AcOH. The resulting solid was filtered and dried to afford 6.2 g (73%) of the desired product, mp 247°-250° C.

Provenance & Evidence