[CH2:1]([O:3][C:4]([C:6]1([OH:9])[CH2:8][CH2:7]1)=[O:5])[CH3:2].[H-].[Na+].C1OCCOCCOCCOCCOC1.[Br:27][C:28]1[CH:33]=[CH:32][C:31](O)=[C:30]([N+:35]([O-:37])=[O:36])[C:29]=1F>C1COCC1>[CH2:1]([O:3][C:4]([C:6]1([O:9][C:31]2[CH:32]=[CH:33][C:28]([Br:27])=[CH:29][C:30]=2[N+:35]([O-:37])=[O:36])[CH2:8][CH2:7]1)=[O:5])[CH3:2]
To a stirred solution of ethyl-1-hydroxycyclopropane carboxylate (2.93 g, 20.5 mmol) in THF (50 mL) was added sodium hydride (60% in mineral oil, 981 mg, 24.5 mmol) under argon atmosphere. After 10 min, 15-crown-5 (0.2 mL) followed by 4-bromo-2-nitro-fluorphenol (4.5 g, 20.5 mmol) were added. The reaction mixture was stirred at room temperature overnight then quenched by the addition of methanol (1.5 mL) and diluted with ethyl acetate. The mixture was washed with brine, and the organic layer was dried over anhydrous sodium sulfate, concentrated and purified by silica gel column chromatography to give 1-(4-bromo-2-nitro-phenoxy)-cyclopropanecarboxylic acid ethyl ester (3.51 g).
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