[H-].[Na+].[CH3:3][O:4][C:5]1[C:14]2[C:13](=[O:15])[O:12][C:11](=[O:16])[NH:10][C:9]=2[CH:8]=[CH:7][C:6]=1[O:17][CH3:18].I[CH2:20][CH3:21]>CN(C)C=O>[CH2:20]([N:10]1[C:9]2[CH:8]=[CH:7][C:6]([O:17][CH3:18])=[C:5]([O:4][CH3:3])[C:14]=2[C:13](=[O:15])[O:12][C:11]1=[O:16])[CH3:21]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.
Wird geladen…
