[H-].[Na+].[C:3]([O:11][CH2:12][CH3:13])(=[O:10])[CH2:4][C:5]([O:7][CH2:8][CH3:9])=[O:6].Br[CH2:15][CH2:16][CH2:17][CH2:18][Cl:19].Cl>O1CCCC1>[Cl:19][CH2:18][CH2:17][CH2:16][CH2:15][CH:4]([C:5]([O:7][CH2:8][CH3:9])=[O:6])[C:3]([O:11][CH2:12][CH3:13])=[O:10]To 458 ml of dry tetrahydrofuran (THF) was added 13.4 g of 60% sodium hydride, and 160.6 g of diethyl malonate was added dropwise with stirring under ice-cooling. After addition, stirring was continued for 15 minutes, and 57.3 g of 1-bromo-4-chlorobutane was added. The mixture was stirred for 50 hours at room temperature. The reaction solution was poured into ice-cold water, neutralized with dilute hydrochloric acid and extracted with ethyl acetate. The organic layer was washed with brine, dried over anhydrous magnesium sulfate and concentrated. The residue was distilled under reduced pressure to provide 26.8 g of the objective compound as colorless oil. B.p. 127–130° C. (5 mmHg).
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