2,3-Dichloro-5,6-dicyano-1,4-benzoquinone → Methyl 3-oxo-2-phenyl-3,4-dihydroquinoxaline-6-carboxylate

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Reaction Steps

DDQ (21.25 g, 93.6 mmol, 2.62 equiv) was added to a stirred solution of methyl 3-oxo-2-phenyl-1,2,3,4-tetrahydroquinoxaline-6-carboxylate (10.07 g, 35.7 mmol, 1.00 equiv) in dioxane (750 mL) and allowed to react, with stifling, overnight at room temperature. The solids were collected by filtration. The filter cake was washed with 2×500 mL of aqueous K2CO3 (saturated). This resulted in 7.29 g (crude) of methyl 3-oxo-2-phenyl-3,4-dihydroquinoxaline-6-carboxylate as an off-white solid. LC-MS (ES, m/z): 281 [M+H]+.

Provenance & Evidence