Methanesulfonic Acid → ethyl 2-chloro-11-fluoro-12,12a-dihydro-6H-pyrido[2',3':5,6][1,3]oxazino[3,4-a]indole-6-carboxylate

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Reaction Conditions

Reaction Steps

To a solution of 6-chloro-2-(4-fluoroindolin-2-yl)pyridin-3-ol (8.53 g, 32.31 mmol) and Glyoxylic acid ethyl ester (6.59 g, 64.59 mmol) in THF (80 mL), MsOH (0.31 g, 3.23 mmol) was added. The mixture was stirred at 50° C. for 2 hours. The mixture was diluted with water and extracted with EtOAc. The organic layer was washed with brine (30 mL), dried over Na2SO4 and concentrated in vacuo. The resulting residue was purified using column chromatography (petroleum ether:EtOAc=10:1) to provide ethyl 2-chloro-11-fluoro-12,12a-dihydro-6H-pyrido[2′,3′:5,6][1,3]oxazino[3,4-a]indole-6-carboxylate (10.2 g, yield: 90.3%). 1H-NMR (CDCl3, 400 MHz) δ 7.04˜7.13 (m, 3H), 6.63 (d, J=8.0 Hz, 1H), 6.55 (t, J=8.4 Hz, 1H), 6.03 (s, 1H), 5.09 (d, J=8.8 Hz, 1H), 4.22˜4.34 (m, 2H), 3.73 (d, J=16.4 Hz, 1H), 3.44˜3.51 (m, 1H), 1.29 (d, J=7.2 Hz, 3H). MS (M+H)+: 349.

Provenance & Evidence