Chloroform → Ethyl (s)-10-fluoro-3-methyl-7-oxo-2,3-dihydro-7h-[1,4]oxazino[2,3,4-ij]quinoline-6-carboxylate

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Reaction Steps

Ethyl 3-dimethylamino-2-(2,3,4-trifluorobenzoyl)acrylate (15.0 g, 49.8 mmol) was dissolved in ethanol (30 ml), and to this solution, an ethanol (10 ml) solution of (S)-2-amino-1-propanol (4.50 g, 59.8 mmol) was added dropwise while stirring and cooling with ice. After completion of dripping, the reaction solution was stirred for 1 hour at room temperature and then concentrated under a reduced pressure. The residue obtained was dissolved in dimethyl sulfoxide (50 ml), and after adding spray-dried calcium fluoride (16 g) thereto, it was stirred at 120° C. for 26 hours. After letting the reaction suspension cool, the reaction suspension was concentrated under a reduced pressure, chloroform (200 ml) and water (200 ml) were added to the residue, and after performing a separation operation, the water layer was extracted using chloroform (200 ml). The combined organic layers were then washed with saturated saline solution (100 ml) and then dried over anhydrous sodium sulfate. After filtering, the filtrate was concentrated under a reduced pressure, the residue obtained was applied to a silica gel chromatography, and 5.60 g (39%) of the title compound was obtained as a white powder from a chloroform:methanol=50:1 eluate.

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