[Cl:1][C:2]1[CH:7]=[C:6]([O:8][CH3:9])[CH:5]=[CH:4][C:3]=1[CH2:10][C:11]([C:13]1[CH:14]=[CH:15][C:16]2[O:21][CH2:20][C:19](=[O:22])[N:18]([CH3:23])[C:17]=2[CH:24]=1)=[O:12].[H-].[Na+].[CH3:27]I>O1CCCC1>[Cl:1][C:2]1[CH:7]=[C:6]([O:8][CH3:9])[CH:5]=[CH:4][C:3]=1[CH:10]([CH3:27])[C:11]([C:13]1[CH:14]=[CH:15][C:16]2[O:21][CH2:20][C:19](=[O:22])[N:18]([CH3:23])[C:17]=2[CH:24]=1)=[O:12]To a solution of 6-[2-(2-chloro-4-methoxy-phenyl)-acetyl]-4-methyl-4H-benzo[1,4]oxazin-3-one (5.9 g, 17 mmol) in tetrahydrofuran (380 ml) was added sodium hydride (60% dispersion in mineral oil, 0.72 g, 17.9 mmol). The mixture was stirred at room temperature for 1.5 h and then placed in an ice bath. A solution of methyl iodide (2.54 g, 17.9 mmol) in tetrahydrofuran (15 ml) was added dropwise (5 min) The ice bath was removed and the mixture was stirred at 35° C. for 3.5 h. The reaction mixture was poured on ice-water and extracted twice with AcOEt. The organic phases were washed with water and brine, dried (MgSO4), filtered and concentrated. The product was purified by column chromatography (SiO2, heptane/EtOAc 2:1) to give the title compound (3.3 g) as a light yellow foam. MS (m/e)=360.2 [M+H+].
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