C(=O)([O-])[O-].[Ca+2].O.C([O:10][C:11]1[CH2:15][CH2:14][CH2:13][C:12]=1[CH2:16][CH2:17][CH2:18][CH2:19][CH2:20][O:21][C:22](=[O:24])[CH3:23])(=O)C.BrBr>CN(C)C(=O)C.C(Cl)(Cl)(Cl)Cl.C(Cl)(Cl)Cl>[C:22]([O:21][CH2:20][CH2:19][CH2:18][CH2:17][CH2:16][C:12]1[C:11](=[O:10])[CH2:15][CH2:14][CH:13]=1)(=[O:24])[CH3:23]To a well stirred mixture of 405 g. (4.05 moles) of calcium carbonate, 3 l. of water, and 2.5 l. of chloroform cooled to 5° C. is added simultaneously 1016 g. (4.0 moles) of 1-acetoxy-2-(5-acetoxy-pentyl)-1-cyclopentene (Example 56) and a solution of 648 g. (4.05 moles) of bromine in 500 ml. of carbon tetrachloride at a rate to maintain a temperature below 10° C. The mixture is stirred for half an hour after addition of the reagents and the phases are then separated. The organic phase is washed with 2% sodium thiosulfate solution, water, and saturated brine, dried (MgSO4), and evaporated in vacuo to an oil. The oil is immediately added to a refluxing slurry of 500 g. (5.0 moles) of calcium carbonate in 2.5 l. of N,N-dimethylacetamide under nitrogen and the mixture is then refluxed for thirty minutes. The mixture is cooled, filtered, and partitioned between water and diethyl ether. The organic phase is washed with water and saturated brine, dried (MgSO4), and evaporated to yield 757 g. of an oil, b.p. 116°-118° C. (0.25 mm.).
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