反应详情

To a stirred suspension of sodium Hydride (4.64 g, 116 mmol) in N,N-Dimethyl formamide (DMF) (50 mL) in an ice bath under N2 was added 5,6-dimethoxy-1H-benzo[d][1,3]oxazine-2,4-dione (22 g, 97 mmol) in N,N-Dimethylformamide (DMF) (350 mL). After stirring for 15 min at r.t., iodoethane (15.61 mL, 193 mmol) in N,N-Dimethylformamide (DMF) (50 mL) was added dropwise, and the resulting mixture was allowed to stir at r.t. overnight. The mixture was concentrated in vacuo to one-third of the original volume and then poured into ice-water (600 mL). The precipitate was collected by filtration and recrystallized from THF to afford 1-ethyl-5,6-dimethoxy-1H-benzo[d][1,3]oxazine-2,4-dione (15 g, 54.3 mmol, 56.2% yield) as a light brown pellet.

1. stirringto stir at r.t. overnight
2. concentrationThe mixture was concentrated in vacuo to one-third of the original volume
3. additionpoured into ice-water (600 mL)
4. filtrationThe precipitate was collected by filtration
5. customrecrystallized from THF