Diethyl Oxalate → 4-[3-(2,4-Dichlorophenyl)-1,9-dimethyl-2-oxo-2,9-dihydro-1H-pyrido[2,3-b]indol-6-yl]-2,4-dioxobutyric acid ethyl ester

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Reaction Steps

940 mg (6.4 mmol) of diethyl oxalate are dissolved in 5 ml of anhydrous THF. 273 mg (6.8 mmol) of 60% NaH are added and the mixture is stirred at ambient temperature for 10 minutes. A solution of 1.3 g (3.2 mmol) of compound 6-(bromoacetyl)-3-(2,4-dichlorophenyl)-1,9-dimethyl-1,9-dihydro-2H-pyrido[2,3-b]indol-2-one from preparation 1.2 above and 18 mg (0.052 mmol) of dibenzo-18-crown-6 dissolved in 20 ml of anhydrous THF is added, as are a few drops of anhydrous EtOH. The mixture is heated at 70° C. under argon for 3 hours. The mixture is allowed to return to ambient temperature. EtOAc is added to the reaction medium and the organic phase is washed with a 1N HCl solution. The organic phase is evaporated to dryness and the product obtained is triturated in water and filtered. The product is taken up in EtOH and evaporated to dryness.

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