Cl[C:2](=[O:8])[C:3]([O:5][CH2:6][CH3:7])=[O:4].[Cl:9][C:10]1[CH:18]=[C:17]2[C:13]([CH:14]=[C:15]([C:20]([O:22][CH2:23][CH3:24])=[O:21])[N:16]2[CH3:19])=[CH:12][CH:11]=1>ClCCCl.[Ti](Cl)(Cl)(Cl)Cl>[Cl:9][C:10]1[CH:18]=[C:17]2[C:13]([C:14]([C:2](=[O:8])[C:3]([O:5][CH2:6][CH3:7])=[O:4])=[C:15]([C:20]([O:22][CH2:23][CH3:24])=[O:21])[N:16]2[CH3:19])=[CH:12][CH:11]=1A solution of 7.1 ml (63.6 mmol) of ethyl chlorooxoacetate in 100 ml of 1,2-dichloroethane is cooled to 0° C. 7.0 ml (63.6 mmol) of titanium tetrachloride are added in small portions and the mixture is stirred for 30 min at 0° C. A solution of 7.4 g (35.3 mmol) of ethyl 6-chloro-1-methyl-1H-indole-2-carboxylate is added and the mixture is stirred for 3 h at room temperature. The mixture is poured onto water and the organic phase is separated by settling, washed with dilute sodium hydroxide solution, dried over sodium sulphate and concentrated under reduced pressure to produce an oil which is purified by chromatography on a silica column (eluant: cyclohexane/dichloromethane: 2/8). 9.51 g (29.4 mmol) of compound are isolated in the form of a white solid.
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