[CH:1]1([OH:6])[CH2:5][CH2:4][CH2:3][CH2:2]1.[H-].[Na+].[CH3:9][O:10][C:11]([C:13]1[CH:14]=[N:15][C:16](Cl)=[C:17]([Br:19])[CH:18]=1)=[O:12]>CN(C=O)C>[CH3:9][O:10][C:11]([C:13]1[CH:14]=[N:15][C:16]([O:6][CH:1]2[CH2:5][CH2:4][CH2:3][CH2:2]2)=[C:17]([Br:19])[CH:18]=1)=[O:12]Cyclopentanol (1 mL, 11 mmol) was dissolved in DMF (25 mL) and a dispersion of sodium hydride in oil (55–65%, 480 mg) was added at room temperature. The mixture was stirred for 1 h at room temperature and 5-bromo-6-chloro-3-pyridinecarboxylic acid methyl ester (2.5 g, 10 mmol) was added. Stirring was continued for 1 h at room temperature and the mixture was afterwards partitioned between water and diethyl ether. Organic phases were pooled, dried with MgSO4 and the solvent was evaporated. The residue was purified by column chromatography on silica (n-heptane/ethyl acetate 9:1) to yield 0.48 g of the title compound as a colorless oil, MS (EI) 299.0, 301.0 (M)+.
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