[CH3:1][CH:2]1[N:15]2[C:6]([CH2:7][O:8][C:9]3[C:14]2=[CH:13][C:12]([N+:16]([O-])=O)=[C:11]([CH3:19])[CH:10]=3)=[N:5][NH:4][C:3]1=[O:20].[Cl-].[NH4+]>CO.C1COCC1.[Zn]>[NH2:16][C:12]1[CH:13]=[C:14]2[C:9](=[CH:10][C:11]=1[CH3:19])[O:8][CH2:7][C:6]1[N:15]2[CH:2]([CH3:1])[C:3](=[O:20])[NH:4][N:5]=1To a solution of 4,7-dimethyl-6-nitro-2,10-dihydro-9-oxa-1,2,4a-triaza-phenanthren-3-one (0.085 g, 0.31 mmol) and ammonium chloride (0.164 g, 3.1 mmol) in MeOH (10 mL) and THF (10 mL) was added zinc powder (0.200 g, 3.1 mmol) and the resulting mixture was heated at 70° C. for 4 h. The reaction mixture was cooled to ambient temperature, filtered and the filtrate was washed with MeOH (15 mL). The filtrate was concentrated in vacuo and the residue was dissolved in water (20 mL). The aqueous solution was extracted with EtOAc (3×15 mL) and the combined organic phase was dried over anhydrous Na2SO4, filtered and concentrated to give 6-amino-4,7-dimethyl-2,10-dihydro-9-oxa-1,2,4a-triaza-phenanthren-3-one (0.060 g, 0.24 mmol, 79%) as a solid, which was used directly in the next step. TLC (eluting with 25% EtOAc in petroleum ether) Rf=0.2.
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