[NH2:1][C:2]1[CH:7]=[C:6]([O:8][CH3:9])[C:5]([O:10][CH3:11])=[CH:4][C:3]=1[C:12](=[O:14])[CH3:13].C[O-].[Na+].[CH:18](OCC)=O.CCOC(C)=O>COCCOC.O>[CH3:11][O:10][C:5]1[CH:4]=[C:3]2[C:2](=[CH:7][C:6]=1[O:8][CH3:9])[NH:1][CH:18]=[CH:13][C:12]2=[O:14]
To a solution of 1-(2-amino-4,5-dimethoxyphenyl)ethanone (9.80 g, 50 mmol, Lancaster Synthesis LTD) in DME (300 mL) at rt was added NaOMe (15.0 g, 278 mmol), and the mixture was stirred for 30 minutes at rt. To this mixture was added ethyl formate (25 mL) dropwise with stirring at rt. After an hour the reaction was quenched by adding aq HCl (50 mL of 2N HCl), stirred for 10 minutes and the precipitate was filtered, washed with a small amount of H2O and EtOAc to obtain the 1st crop of product. To the filtrate solution was added EtOAc (200 mL), the EtOAc layer was separated, the aqueous layer was washed with EtOAc (200 mL), and the combined EtOAc solution was dried over MgSO4, concentrated in vacuo and the residue was triturated with a small amount of CH3OH/EtOAc to obtain the 2nd crop of product. The solids of 1st crop and 2nd crop were combined, mixed with water (100 mL), stirred for 10 minutes, the solid was filtered and dried to obtain the product (9.75 g, 95%) as a white solid. 1H NMR (DMSO-d6) δ 8.50 (s, 1H), 7.75 (d, 1H, J=4.2 Hz), 7.42 (s, 1H), 7.08 (s, 1H), 5.91 (d, 1H, J=4.2 Hz), 3.83 (s, 3H), 3.80 (s, 3H).
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