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

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Reaction Conditions

Reaction Steps

Potassium hydroxide (180 mg) and tetrabutylammonium hydrogensulfate (90.4 mg) were dissolved in DMF (15 ml) by heating to 60° C. and a solution of diethyl [2,3,4-trifluoro[(1S)-2-hydroxy-1-methylethyl]anilino]methylenemalonate (1g, 99.8% ee) and diethyl ethoxymethylenemalonate (120 mg) in DMF 85 ml) was added thereto. The obtained mixture was stirred at the same temperature for 2 hours. After adding water, the liquid reaction mixture was extracted with ethyl acetate. The organic layer was dried over anhydrous magnesium sulfate. After evaporating the solvent, the obtained residue was subjected to silica gel column chromatography. Thus, 852 mg (99.8% ee) of the title compound was obtained as a yellow oily substance. Various spectral data was identical with those described in Japanese Patent No. 2,769,174.

Provenance & Evidence