2,3-Dichloro-5,6-dicyano-1,4-benzoquinone → HCID 476293, compound

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Reaction Steps

500 mg (1.18 mmol) 3-[1-(2-cyanoethyl)-5-methoxy-3-indolyl]-4-(1-methyl-3-indolyl)-1H-pyrrole-2,5-dione in 50 ml toluene are heated under reflux for 30 minutes with 225 mg (1.18 mmol) p-toluenesulphonic acid hydrate and 315 mg (1.39 mmol) 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ). After cooling, the reaction mixture is evaporated in a vacuum and the residue is stirred with 100 ml 0.1N sodium hydroxide solution. The aqueous suspension is saturated with sodium chloride and extracted twice with, in each case, 100 ml tetrahydrofuran. The tetrahydrofuran solutions are washed twice with, in each case, 100 ml saturated sodium chloride solution. The residue is chromatographed on silica gel with toluene/acetone (4:1 v/v). The fraction with the Rf 0.3 is isolated, stirred up with diisopropyl ether and the crystals formed are filtered off. There are obtained 270 mg (54% of theory) 13-(2-cyanoethyl)-6,7,12,13-tetrahydro-3-methoxy-12-methyl-5,7-dioxo-5H-indolo[2,3-a]pyrrolo[3,4-c]carbazole in the form of yellow crystals which decompose from about 260° C. with the evolution of gas.

Provenance & Evidence