[CH3:1][O:2][C:3](=[O:12])[CH2:4][C:5]1[CH:10]=[CH:9][CH:8]=[C:7]([Br:11])[CH:6]=1.[H-].[Na+].Br[CH2:16][CH2:17][O:18][CH2:19][CH2:20]Br>CN(C=O)C>[CH3:1][O:2][C:3]([C:4]1([C:5]2[CH:10]=[CH:9][CH:8]=[C:7]([Br:11])[CH:6]=2)[CH2:20][CH2:19][O:18][CH2:17][CH2:16]1)=[O:12]A solution of (3-bromo-phenyl)-acetic acid methyl ester (0.6 g, 2.62 mmol) in dry N,N′-dimethylformamide is added to a stirred suspension of sodium hydride (60% in mineral oil, 0.26 g, 6.55 mmol) in dry N,N′-dimethylformamide at 0° C. and stirring is continued for 20 minutes. A solution of bis(2-bromoethyl) ether (0.39 mL, 3.14 mmol) in N,N-dimethylformamide is added drop-wise and the reaction mixture is stirred overnight, while warming to room temperature. The reaction is quenched with water, extracted twice with ethyl acetate, the combined extracts is washed with brine and water, dried over sodium sulfate, filtered and concentrated in vacuo to afford 4-(3-bromo-phenyl)-tetrahydro-pyran-4-carboxylic acid methyl ester (610 mg) used in the next step without further purification. LCMS: RT=2.81 minutes; MS: 299, 301 (M+H).
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