[Br:1][C:2]1[CH:7]=[CH:6][C:5]([CH2:8][C:9]([C:11]2[CH:21]=[CH:20][C:14]3[N:15]([CH3:19])[C:16](=[O:18])[O:17][C:13]=3[CH:12]=2)=[O:10])=[C:4]([Cl:22])[CH:3]=1.[H-].[Na+].[CH3:25]I>CN(C=O)C>[Br:1][C:2]1[CH:7]=[CH:6][C:5]([CH:8]([CH3:25])[C:9]([C:11]2[CH:21]=[CH:20][C:14]3[N:15]([CH3:19])[C:16](=[O:18])[O:17][C:13]=3[CH:12]=2)=[O:10])=[C:4]([Cl:22])[CH:3]=16-[2-(4-Bromo-2-chloro-phenyl)-acetyl]-3-methyl-3H-benzooxazol-2-one (747 mg) was dissolved in DMF (20 mL). The mixture was cooled to 0° C. To this solution was added sodium hydride (55% in mineral oil, 90 mg). The mixture was stirred for 10 minutes at 0° C. and then for 1 hour at r.t. The mixture was cooled to 0° C. and methyl iodide (292 mg) was added dropwise over a period of 10 minutes. Stirring was continued over night at r.t. The reaction mixture was poured into ice/water and extracted two times with ethyl acetate. The combined organic layers were washed with brine, dried over Na2SO4, filtered and the solvent was evaporated. The residue was purified by flash chromatography (silica gel, gradient of heptane in ethyl acetate) to give the title compound as a brown foam (531 mg, 69%). MS (neg. ion, m/e)=394.2 [(M−H)−].
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