Cesium carbonate → 2-chloro-11-fluoro-6H-pyrido[2',3':5,6][1,3]oxazino[3,4-a]indole

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Reaction Steps

A solution of 6-chloro-2-(4-fluoro-1H-indol-2-yl)pyridin-3-ol (2 g, 7.6 mmol) and Cs2CO3 (7.46 g, 22.89 mmol) in DMF (100 mL) was stirred at 100° C. (internal temperature) for 15 min, and then chloroiodomethane (2.85 g, 15.3 mmol) in DMF (2 mL) was added dropwise. After the reaction was completed, the mixture was filtered and concentrated in vacuo. The resulting residue was diluted with water (50 mL) and extracted with ethyl acetate (30 mL×3). The organic layer was washed with brine, dried over Na2SO4 and concentrated in vacuo. The resulting residue was purified using column chromatography (petroleum ether:EA=10:1) to provide 2-chloro-11-fluoro-6H-pyrido[2′,3′:5,6][1,3]oxazino[3,4-a]indole (1.8 g, yield: 86.1%). 1H-NMR (DMSO-d6, 400 MHz) δ 7.64 (d, J=8.8 Hz, 1H), 7.39˜7.46 (m, 2H), 7.21˜7.25 (m, 1H), 7.06 (s, 1H), 6.88˜6.92 (m, 1H), 6.18 (s, 2H). MS (M+H)+: 275/277.

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