[C:1]([O:9][CH2:10][CH3:11])(=[O:8])[CH2:2][C:3]([O:5][CH2:6][CH3:7])=[O:4].[H-].[Na+].[Cl:14][C:15]1[CH:20]=[C:19]([Cl:21])[CH:18]=[C:17]([Cl:22])[C:16]=1Br.Cl>[Cu]Br.O1CCOCC1>[Cl:14][C:15]1[CH:20]=[C:19]([Cl:21])[CH:18]=[C:17]([Cl:22])[C:16]=1[CH:2]([C:3]([O:5][CH2:6][CH3:7])=[O:4])[C:1]([O:9][CH2:10][CH3:11])=[O:8]
Diethyl malonate (6.21 mol) is added to a mixture of sodium hydride (5.13 mol) and 1,4-dioxane (1400 ml) at 55 to 60° C. within 3 hours. The mixture is stirred for 10 minutes at 55° C. and copper(I) bromide (0.5 mol) is added. A mixture of 2,4,6-trichlorobromobenzene (2.50 mol) and 1,4-dioxane (600 ml) is added. The reaction mixture is heated at 100° C. for 14 hours and cooled to 15° C. Hydrochloric acid (12N, 350 ml) is added slowly at 15 to 20° C. The organic phase is separated off and the aqueous phase is extracted with ethyl acetate (250 ml) and toluene (200 ml). The combined organic phases are concentrated in vacuo. The residue is filtered over silica gel, washed with petroleum ether/ethyl acetate (15:1) and the solvent is distilled off. The residue is distilled in vacuo to yield 540 g of the product as a white solid, 144-150° C. at 0.4 mbar.
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