[F:1][C:2]1([F:29])[CH2:28][CH:5]2[CH:6]([C:18]3[CH:23]=[CH:22][C:21]([O:24]COC)=[CH:20][CH:19]=3)[O:7][C:8]3[CH:9]=[CH:10][C:11]([O:14]COC)=[CH:12][C:13]=3[CH:4]2[CH2:3]1>C1COCC1.Cl.CCOC(C)=O>[F:29][C:2]1([F:1])[CH2:28][C@@H:5]2[C@H:6]([C:18]3[CH:23]=[CH:22][C:21]([OH:24])=[CH:20][CH:19]=3)[O:7][C:8]3[CH:9]=[CH:10][C:11]([OH:14])=[CH:12][C:13]=3[C@@H:4]2[CH2:3]1Stir a solution of difluorocyclopentane 29 (196 mg, 0.480 mmol) in 7 mL of THF and 3 mL of 3 M HCl overnight. Add 1 mL of 5 M HCl and let stir overnight. Dilute the solution with EtOAc. Separate the aqueous solution and extract 2× with EtOAc. The combined organic solutions were washed with saturated aqueous sodium bicarbonate, brine, dried over Na2SO4, filtered, and concentrated. Absorb to 2 g of silica gel and purify by silica gel chromatography (10 g silica gel, 10 to 60% EtOAc/Hexanes over 30 min at 35 mL/min) to give 155 mg (0.48 mmol, 100%) of difluorocyclopentane 30. The enantiomers were separated by preparative chiral chromatography (Chiralpak AD, 65/35 heptane/ethanol).
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