2,3-Dichloro-5,6-dicyano-1,4-benzoquinone → ethyl 2-chloro-11-fluoro-6H-pyrido[2',3':5,6][1,3]oxazino[3,4-a]indole-6-carboxylate

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Reaction Steps

To a solution of ethyl 2-chloro-11-fluoro-12,12a-dihydro-6H-pyrido[2′,3′:5,6][1,3]oxazino[3,4-a]indole-6-carboxylate (10.22 g, 29.36 mmol) and DDQ (8.67 g, 38.17 mmol) in toluene (80 mL) was stirred at 80° C. for 2 hours. The mixture was then diluted with water (50 mL) and extracted with EtOAc (30 mL*3). The organic layer was washed with brine (30 mL), dried over Na2SO4 and concentrated. The residue was purified by column chromatography (PE:EtOAc=20:1) to afford ethyl 2-chloro-11-fluoro-6H-pyrido[2′,3′:5,6][1,3]oxazino[3,4-a]indole-6-carboxylate (8.64 g, yield: 85%), which was also prepared from 6-chloro-2-(4-fluoro-1H-indol-2-yl)pyridin-3-ol and methyl 2,2-dibromoacetate in the presence of base, such as DBU etc. 1H-NMR (CDCl3, 400 MHz) δ 7.33 (d, J=8.4 Hz, 1H), 7.30 (s, 1H), 7.09˜7.18 (m, 3H), 6.78˜6.83 (m, 1H), 6.52 (s, 1H), 3.96˜4.09 (m, 2H), 1.02 (t, J=7.2 Hz, 3H). MS (M+H)+: 347.

Provenance & Evidence