CC[O-].[Na+].[Na].[C:6]([O:14][CH2:15][CH3:16])(=[O:13])[CH2:7][C:8]([O:10][CH2:11][CH3:12])=[O:9].Br[CH2:18][CH2:19][CH:20]=[CH2:21]>CCO>[CH2:21]([CH:7]([C:8]([O:10][CH2:11][CH3:12])=[O:9])[C:6]([O:14][CH2:15][CH3:16])=[O:13])[CH2:20][CH:19]=[CH2:18]A solution of NaOEt, prepared from the treatment of 1 L EtOH with sodium metal (19.5 g, 0.813 mol), was cooled to 0° C. and diethyl malonate (3-1, 100 g, 0.625 mol) was added dropwise over 0.5 h. After the addition was complete, the reaction was stirred for an additional 0.5 h, then a solution of 1-bromo-3-butene (76.1 mL, 0.75 mol) in 100 mL EtOH was added dropwise over forty-five minutes. The reaction was heated to reflux for 18 h, cooled and the solvent was removed in vacuo. The residue was dissolved in H2O and washed with EtOAc. The organic layer was dried with brine and MgSO4, filtered and evaporated. Fractional distillation of the residue (0.25-0.4 mm Hg, 70°-80° C.) gave 3-2 as a clear liquid.
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