[NH2:1][C:2]1[CH:11]=[CH:10][C:5]([C:6]([O:8][CH3:9])=[O:7])=[CH:4][C:3]=1[Br:12].[CH3:13][C:14]1([CH3:22])[O:21][C:19](=[O:20])[CH2:18][C:16](=[O:17])[O:15]1.[CH:23](OCC)(OCC)OCC>C(O)(C)C>[Br:12][C:3]1[CH:4]=[C:5]([CH:10]=[CH:11][C:2]=1[NH:1][CH:23]=[C:18]1[C:19](=[O:20])[O:21][C:14]([CH3:22])([CH3:13])[O:15][C:16]1=[O:17])[C:6]([O:8][CH3:9])=[O:7]To a suspension of methyl 4-amino-3-bromobenzoate (2 g, 8.69 mmol) in isopropanol (10 mL) was added Meldrum's acid (1.63 g, 11 mmol) and triethyl orthoformate (5.26 mL, 31.6 mmol). The resulting mixture was heated at 100° C. for 4 hr and cooled to room temperature. The resulting precipitates were filtered off and washed with 10% Et2O/hexanes to yield methyl 3-bromo-4-(((2,2-dimethyl-4,6-dioxo-1,3-dioxan-5-ylidene)methyl)amino)benzoate. (M+Na)+: 408.
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