Indole → 5-[(Indol-3-yl)carbonyl]-4,5,6,7-tetrahydrobenzimidazole

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Reaction Steps

4 g of N-[(4,5,6,7-tetrahydrobenzimidazol-5-yl)carbonyl]pyrrolidine hydrochloride obtained in Example 5 were added to 40 ml of dichloroethane, and 2.74 g of indole and 4.4 ml of phosphorus oxychloride were added thereto. The mixture was stirred at 80° to 85° C. for 7 hours and then at room temperature overnight. To the mixture was added 40 ml of a cold potassium carbonate aqueous solution, followed by extraction with chloroform. The extract was dried over anhydrous magnesium sulfate, and the solvent was removed by distillation under reduced pressure. The residue was subjected to column chromatography using chloroform/methanol as an eluent to obtain 1.82 g of 5-[(indol-3-yl)carbonyl]-4,5,6,7-tetrahydrobenzimidazole as a foam-like substance. In 1 ml of methanol were dissolved 0.16 g of the resulting product and 0.06 g of fumaric acid, and 5 ml of acetonitrile was added to the solution. The formed crystal was collected by filtration to obtain 0.13 g of 5-[(indol- 3-yl)carbonyl]-4,5,6,7-tetrahydrobenzimidazole fumarate.

Provenance & Evidence