Br[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][C:3]=1[O:8][CH3:9].C([Li])CCC.[C:15](OCC)(=[O:21])[C:16]([O:18][CH2:19][CH3:20])=[O:17].[NH4+].[Cl-]>CCOCC.CCCCC>[CH3:9][O:8][C:3]1[CH:4]=[CH:5][CH:6]=[CH:7][C:2]=1[C:15](=[O:21])[C:16]([O:18][CH2:19][CH3:20])=[O:17]A solution of 27 g of 1-bromo-2-methoxybenzene in 270 ml of ether is cooled to −70° C. under an argon atmosphere, 90 ml of a 1.6 M solution of n-butyl-lithium in pentane are added dropwise and the mixture is then left stirring for 45 minutes. 78 ml of diethyl oxalate are added rapidly and the mixture is left stirring, while allowing the temperature to return to RT. After stirring for 1 hour at RT, saturated NH4Cl solution is added to the mixture, the phases are separated after settling has taken place, the aqueous phase is extracted with ether, the combined organic phases are washed with water and then with saturated NaCl solution and dried over Na2SO4, and the solvents are evaporated off under vacuum. The excess diethyl oxalate is removed by distillation under vacuum (b.p.=87° C. at 2 000 Pa). The resulting product is chromatographed on silica gel, eluting with a DCM/hexane mixture (50/50; v/v) and then with DCM. The product obtained is purified by distillation under vacuum. 13 g of the expected product are obtained; b.p.=110° C. at 3 Pa.
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