[CH2:1]([O:3][C:4]([CH2:6][N:7]1[C:12]2[CH:13]=[CH:14][C:15]([N+:17]([O-])=O)=[CH:16][C:11]=2[O:10][CH2:9][C:8]1=[O:20])=[O:5])[CH3:2].C(O)C.[H][H]>[C].[Pd].O1CCCC1>[NH2:17][C:15]1[CH:14]=[CH:13][C:12]2[N:7]([CH2:6][C:4]([O:3][CH2:1][CH3:2])=[O:5])[C:8](=[O:20])[CH2:9][O:10][C:11]=2[CH:16]=1
A mixture of 4-ethoxycarbonylmethyl-7-nitro-2H-1,4-benzoxazin-3(4H)-one (30 g), 10% palladium-carbon (3 g) and ethanol (150 ml) was charged in an autoclave, and catalytically reduced under conditions of 20 kg/cm2 of hydrogen pressure and at a temperature of 60° C. to 70° C. Tetrahydrofuran was added thereto, and the liquor was filtered, then the filtrate was distilled under reduced pressure. Recrystallization of the resulting solid from ethanol gave the desired 7-amino-4-ethoxycarbonylmethyl-2H-1,4-benzoxazin-3(4H)-one (20 g). mp. 136°-137° C.
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