[CH2:1]([C:8]1[CH:15]=[C:12]([CH:13]=O)[C:11]([OH:16])=[CH:10][CH:9]=1)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.C(=O)([O-])[O-].[K+].[K+].Br[CH:24](C(OCC)=O)[C:25]([O:27][CH2:28][CH3:29])=[O:26].O>CC(=O)CC>[CH2:1]([C:8]1[CH:9]=[CH:10][C:11]2[O:16][C:24]([C:25]([O:27][CH2:28][CH3:29])=[O:26])=[CH:13][C:12]=2[CH:15]=1)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=16.9 g of 1A was dissolved in 130 ml of 2-butanone. The solution was heated to reflux and 8.1 g of potassium carbonate was added. Then 7.8 g of diethyl bromomalonate was added, drop-by-drop over a 10-minute period. The mixture was stirred at reflux for 58 hours, then was cooled and filtered. The filtrate was concentrated under reduced pressure to leave an oil, which was poured into water. The mixture was extracted with ether. The extract was washed with 5% sodium hydroxide solution, then with water, dried (MgSO4), and concentrated under reduced pressure. The residue was recrystallized from methanol and dried over P2O5 to give 1, mp: 78°-79° C.
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