[CH2:1]([O:3][C:4](=[O:11])[CH2:5][C:6]([O:8][CH2:9][CH3:10])=[O:7])[CH3:2].CC[O-].[Na+].[Na].[CH:17]1([O:23][CH2:24][CH2:25][CH2:26][CH2:27]Br)[CH2:22][CH2:21][CH2:20][CH2:19][CH2:18]1>C(O)C>[CH2:1]([O:3][C:4](=[O:11])[CH:5]([CH2:27][CH2:26][CH2:25][CH2:24][O:23][CH:17]1[CH2:22][CH2:21][CH2:20][CH2:19][CH2:18]1)[C:6]([O:8][CH2:9][CH3:10])=[O:7])[CH3:2]15 g of malonic acid diethyl ester are added dropwise at 50° C. to a solution of sodium ethylate, freshly prepared from 1.5 g of sodium and 30 ml of ethanol. This temperature is maintained for 1 hour and 11.7 g of 4-cyclohexyloxybutyl bromide are then added dropwise. When the addition is complete, the mixture is stirred for 3 hours at 60° C. and is concentrated considerably, 100 ml of ice water are added to the residue and the mixture is extracted 3 times with a total of 150 ml of methylene chloride. The combined organic phases are dried over sodium sulphate and the solvent is removed by distillation in vacuo, together with excess malonic acid diethyl ester. This gives 10.5 g of [4-(cyclohexyloxy)-butyl]-malonic acid diethyl ester in the form of a pale yellow oily residue.
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