反应详情

To a solution of (S)-2-ethyl-7-methoxycarbonyl-3-oxo-3,4-dihydro-2H-1,4-benzoxazine [prepared in Preparation 14(2)] (2.00 g) in dimethylformamide (20 ml) were added 60% sodium hydride (in oil) (0.37 g) and ethyl iodide (1.90 g) and the mixture was stirred under ice cooling for 2 hours. Water was added to the reaction solution and extraction with ethyl acetate was conducted. The solvent was distilled off under reduced pressure and the resulting residue was subjected to purification by column chromatography using ethyl acetate/hexane [1:4 (v/v)] to give (S)-2,4-diethyl-7-methoxycarbonyl-3-oxo-3,4-dihydro-2H-1,4-benzoxazine (2.15 g).

1. distillationThe solvent was distilled off under reduced pressure
2. customthe resulting residue was subjected to purification by column chromatography