II.Br[CH:4]([CH2:12][CH2:13][CH2:14][CH2:15][CH3:16])[C:5]([O:7][CH2:8][C:9](=[O:11])[CH3:10])=[O:6].Cl>O1CCCC1.[Zn]>[OH:11][C:9]1([CH3:10])[CH2:8][O:7][C:5](=[O:6])[CH:4]1[CH2:12][CH2:13][CH2:14][CH2:15][CH3:16]Powdered zinc (39.61 g, 606 mmol) is suspended in 500 ml of tetrahydrofuran. Then, 1.92 g (15 mmol) of iodine are added and 80.34 g (303 mmol) of acetylmethyl 2-bromoheptanoate in 100 ml of tetrahydrofuran are added dropwise at 67° C. within 1 hour. The grey-green suspension is stirred at reflux temperature for a further 1 hour. The cooled reaction mixture is poured onto 500 ml of 1N HCl and ice and stirred for 10 minutes. It is then extracted in a separating funnel with 3×500 ml of ethyl acetate. The organic phases are dried with MgSO4, concentrated on a rotary evaporator and dried in high vacuum. There are obtained 77.21 g of 4-hydroxy-4-methyl-3-pentyl-tetrahydrofuran-2-one.
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