[NH2:1][C:2]1[CH:11]=[CH:10][CH:9]=[CH:8][C:3]=1[C:4]([NH:6][OH:7])=[O:5].[C:12](OC)(OC)(OC)[O:13][CH3:14]>CO>[CH3:12][O:13][C:14]1[N:6]([OH:7])[C:4](=[O:5])[C:3]2[C:2](=[CH:11][CH:10]=[CH:9][CH:8]=2)[N:1]=1A mixture of 22.8 g (0.15 mol) of o-amino-benzhydroxamic acid, 50 ml of methanol and 27.2 g (0.2 mol) of tetramethyl orthocarbonate is boiled under reflux for 2 hours and then cooled to 5° C. The product which crystallizes out is filtered off under suction. In this manner, 17 g (60% of theory) of 2-methoxy-3-hydroxy-3,4-dihydro-4-oxo-quinazoline are obtained in the form of colorless crystals of melting point 220° C. ##STR18##
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