(3,5-Dichlorophenyl)hydrazine monohydrochloride → N-benzyl-5,7-dichloro-1,2,3,4-tetrahydrocarbazole-3,4-dicarboximide

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Reaction Steps

To 30 ml of acetic acid were added 1.54 g of N-benzyl-4-oxocyclohexane-1,2-dicarboximide, 3.0 g of zinc chloride and 1.54 g of 3,5-dichlorophenylhydrazine hydrochloride. The mixture was refluxed for 2 hours. Acetic acid was removed by distillation under reduced pressure. To the residue were added 150 ml of ethyl acetate and 50 ml of water. The organic layer was separated, washed with diluted hydrochloric acid, an aqueous saturated sodium chloride solution, an aqueous saturated sodium hydrogencarbonate solution and an aqueous saturated sodium chloride solution in this order, and dried over anhydrous magnesium sulfate. The solvent was removed by distillation under reduced pressure. The residue was purified by column chromatography (eluant: toluene/ethyl acetate=30/1 to 20/1) to obtain 670 mg (yield: 28%) of N-benzyl-5,7-dichloro-1,2,3,4-tetrahydrocarbazole-3,4-dicarboximide [IR (KBr) cm-1 : 3320, 1770, 1695] and 400 mg (yield: 17%) of N-benzyl-5,7-dichloro-1,2,3,4-tetrahydrocarbazole-2,3-dicarboximide [IR (KBr) cm-1 : 3310, 1765, 1690], both as colorless crystals.

Provenance & Evidence