[C:1]([O:8][CH3:9])(=[O:7])[CH2:2][C:3]([O:5][CH3:6])=[O:4].[Na].Br[CH2:12]/[CH:13]=[CH:14]\[CH2:15][CH2:16][CH2:17][C:18]([O:20][CH3:21])=[O:19]>CO.O>[CH:2]([C:1]([O:8][CH3:9])=[O:7])([C:3]([O:5][CH3:6])=[O:4])[CH2:12]/[CH:13]=[CH:14]\[CH2:15][CH2:16][CH2:17][C:18]([O:20][CH3:21])=[O:19]Dimethyl malonate (39.6 g) is added slowly with cooling and stirring to a solution of 6.9 g of sodium dissolved in 100 ml of absolute methanol and the mixture stirred for 15 min. The bromoester of formula 9, methyl cis-7-bromo-5-heptenoate (65.7 g) is added dropwise. The mixture is heated at reflux for 1 hr., cooled and diluted with water. The mixture is extracted with ether. The ether extracts are dried (Na2SO4) and concentrated. The residue is distilled under reduced pressure to give the title compound, b.p. 140° - 150° C/0.7 mm.
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