[O:1]1[CH2:6][CH2:5][C:4](=[O:7])[CH2:3][CH2:2]1.II.Br[CH2:11][C:12]([O:14][CH2:15][CH3:16])=[O:13].S(=O)(=O)(O)O>O1CCCC1.[Zn]>[OH:7][C:4]1([CH2:11][C:12]([O:14][CH2:15][CH3:16])=[O:13])[CH2:5][CH2:6][O:1][CH2:2][CH2:3]1To a solution of tetrahydro-4H-pyran-4-one (5.5 g, 51.6 mmol), a zinc powder (4.05 g, 61.9 mmol) and a small amount of iodine in tetrahydrofuran (60 ml) was added dropwise ethyl bromoacetate (6.28 ml, 56.7 mmol) under a nitrogen atmosphere. After heating under reflux for 6 hrs., 10% sulfuric acid (50 ml) was carefully added under ice-cooling and the mixture was extracted with ethyl acetate. The extract was washed with saturated aqueous sodium hydrogen carbonate solution, dried over anhydrous MgSO4 and concentrated under reduced pressure to give the title compound (6.73 g, 69%) as a colorless oil.
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