Diethyl (ethoxymethylene)malonate → (S)-Diethyl (7,8-Difluoro-3-Methyl-3,4-Dihydro-2H-[1,4]Benzoxazin-4-Yl)Methylene-Malonate

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Reaction Steps

1.20 g (99.8% ee) of (3S)-7,8-difluoro-3-methyl-3,4-dihydro-2H-[1,4]benzoxazine was dissolved in toluene (0.5 ml). After adding diethyl ethoxymethylenemalonate (1.92 g), the mixture was stirred at 120 for 30 minutes and then at 140° C. under reduced pressure for 30 minutes. The residue was subjected to silica gel column chromatography. Thus, 2.19 g (99.8% ee) of the title compound was obtained as a yellow oily product. The physical constants of the obtained compounds was identical with those described in Japanese Patent No. 2,769,174.

Provenance & Evidence