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

HRID 980882Notes

Reaction equation

[CH3:1][O:2][C:3]1[C:13]([O:14][CH3:15])=[CH:12][CH:11]=[C:10]([NH2:16])[C:4]=1[C:5]([O:7]CC)=O.[CH3:17][N:18]=[C:19]=[O:20].CC(O)=O>N1C=CC=CC=1.O>[CH3:1][O:2][C:3]1[C:13]([O:14][CH3:15])=[CH:12][CH:11]=[C:10]2[C:4]=1[C:5](=[O:7])[N:18]([CH3:17])[C:19](=[O:20])[NH:16]2

Participants

Conditions

Temperature: 0 °C

Procedure

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.

Workup

waitat room temperature for 1 hour
concentrationThe reaction mixture was concentrated to dryness
dissolutionThe 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)
temperaturerefluxed for 2 hours
customThe solvent was removed in vacuo
customto give a light brown solid
filtrationThe resulting solid was filtered
customdried

Sources & evidence

ORD record: ord-71076be22fac415c94a2630d4ae56f73
Source dataset: uspto-grants-1987_01
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US04639518

Reaction notes

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