Diethyl Oxalate → Methyl 7-methoxy-1-[(4-methoxyphenyl)methyl]-2,3-dioxo-1,2,3,4-tetrahydroquinoxaline-6-carboxylate

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Reaction Steps

The solution of methyl 5-amino-2-methoxy-4-(4-methoxybenzylamino)benzoate (30 g, 94.83 mmol) in diethyl oxalate (100 mL) was stirred for 3 h at reflux and then cooled with a water/ice bath and diluted with ether (500 mL). The product was collected by filtration to afford methyl 7-methoxy-1-[(4-methoxyphenyl)methyl]-2,3-dioxo-1,2,3,4-tetrahydroquinoxaline-6-carboxylate as a light yellow solid (25.0 g, 71%).

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