C1(P(C2C=CC=CC=2)CCP(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.[C:29]([Br:33])(Br)(Br)Br.OC[CH2:36][CH2:37][N:38]1[C:46]2[C:41](=[N:42][C:43]([O:47][CH3:48])=[CH:44][CH:45]=2)[CH2:40][C:39]1=[O:49]>ClCCl>[Br:33][CH2:29][CH2:36][CH2:37][N:38]1[C:46]2[C:41](=[N:42][C:43]([O:47][CH3:48])=[CH:44][CH:45]=2)[CH2:40][C:39]1=[O:49]Under argon and in an anhydrous medium, 1.50 g (3.76 mmol) of 1,2-bis-diphenylphosphinoethane are added at 0° C. to a solution of 1.25 g (3.76 mmol) of carbon tetrabromide in 20 ml of dichloromethane. After 10 minutes at 0° C., 417 mg (1.88 mmol) of the compound obtained in Step D dissolved in 10 ml of dichloromethane are added to the mixture. The mixture is stirred for 30 minutes at 0° C., and then for 3 hours at room temperature. After hydrolysis of the reaction mixture, the organic phase is dried over magnesium sulphate, filtered and concentrated. Purification by flash chromatography over silica gel (eluant: petroleum ether/ethyl acetate, 8:2) yields the title compound in the form of a white solid.
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