Cl[C:2]1[N:3]([CH2:10][C:11]([OH:24])([CH3:23])[CH2:12][N:13]2[C:17]3[CH:18]=[CH:19][CH:20]=[CH:21][C:16]=3[O:15][C:14]2=[O:22])[CH:4]=[C:5]([N+:7]([O-:9])=[O:8])[N:6]=1.[H-].[Na+].O1CCOCC1>O>[CH3:23][C:11]1([CH2:12][N:13]2[C:17]3[CH:18]=[CH:19][CH:20]=[CH:21][C:16]=3[O:15][C:14]2=[O:22])[O:24][C:2]2=[N:6][C:5]([N+:7]([O-:9])=[O:8])=[CH:4][N:3]2[CH2:10]1A mixture of 3-[3-(2-chloro-4-nitroimidazol-1-yl)-2-hydroxy-2-methylpropyl]-3H-benzoxazol-2-one prepared in Example 541 (615 mg, 1.74 mmol), sodium hydride (76.6 mg, 1.91 mmol), 1,4-dioxane (15 ml) was stirred under reflux for 1 hour. The reaction mixture was allowed to return to room temperature. To the solution, water was added and the solution was extracted with methylene chloride. The organic phase was dried over sodium sulfate and then filtered. The filtrate was concentrated under reduced pressure, and the residue was purified by silica gel column chromatography (methylene chloride/methanol=30/1) to afford 3-(2-methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazol-2-ylmethyl)-3H-benzoxazol-2-one (209 mg, yield 38%) as a white powder.
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