[CH3:1][O:2][CH:3]([O:10]C)[CH:4]([CH3:9])[C:5](OC)=O.[Br:12][C:13]1[CH:18]=[CH:17][C:16]([N+:19]([O-:21])=[O:20])=[CH:15][C:14]=1[NH2:22].CC1C=CC(S(O)(=O)=O)=CC=1>C1C=CC=CC=1>[Br:12][C:13]1[CH:18]=[CH:17][C:16]([N+:19]([O-:21])=[O:20])=[CH:15][C:14]=1[NH:22][CH:5]=[C:4]([CH3:9])[C:3]([O:2][CH3:1])=[O:10]A mixture of methyl 3,3-dimethoxy-2-methylpropionate (10 g, 46 mmol. Commercially available or can be prepared according to Org. Biomol. Chem. 2006, 4, 2945), 2-bromo-5-nitrophenylamine (12 g, 74 mmol) and p-TsOH (50 mg, 0.29 mmol) in benzene (200 mL) was stirred at reflux for 24 h. The reaction mixture was allowed to cool to room temperature. The reaction mixture was concentrated under reduced pressure. The residue was recrystallized from DCM to afford the desired product (9.8 g, yield: 67.5%) as a solid. 1H NMR (DMSO-d6, 400 MHz): δ=1.86 (s, 3H), 3.29 (s, 3H), 7.64 (dd, J=2.4, 8.4 Hz, 1H), 7.87 (s, 1H), 7.88 (d, J=8.4 Hz, 1H), 8.24 (d, J=2.4 Hz, 1H).
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